Non-Small Cell Lung Cancer Treatment (PDQ®) 3/10 —Health Professional Version - National Cancer Institute

Non-Small Cell Lung Cancer Treatment (PDQ®)—Health Professional Version - National Cancer Institute

Non-Small Cell Lung Cancer Treatment (PDQ®)–Health Professional Version

Stage Information for NSCLC

In This Section

• Background
• Staging Evaluation
  • Evaluation of mediastinal lymph node metastasis
  • Evaluation of brain metastasis
  • Evaluation of distant metastasis other than the brain
• The Revised International System for Staging Lung Cancer
• AJCC Stage Groupings and TNM Definitions

Background

In non-small cell lung cancer (NSCLC), the determination of stage has important therapeutic and prognostic implications. Careful initial diagnostic evaluation to define the location and to determine the extent of primary and metastatic tumor involvement is critical for the appropriate care of patients.

In general, symptoms, physical signs, laboratory findings, or perceived risk of distant metastasis lead to an evaluation for distant metastatic disease. Additional tests such as bone scans and computed tomography (CT)/magnetic resonance imaging (MRI) of the brain may be performed if initial assessments suggest metastases or if patients with stage III disease are under consideration for aggressive local and combined modality treatments.

Stage has a critical role in the selection of therapy. The stage of disease is based on a combination of clinical factors and pathological factors.[1] The distinction between clinical stage and pathological stage should be considered when evaluating reports of survival outcome.

Procedures used to determine staging include the following:

• History.
• Physical examination.
• Routine laboratory evaluations.
• Chest x-ray.
• Chest CT scan with infusion of contrast material.
• Fluorine F 18-fludeoxyglucose positron emission tomography (18F-FDG PET) scanning.

Procedures used to obtain tissue samples include bronchoscopy, mediastinoscopy, or anterior mediastinotomy. Pathological staging of NSCLC requires the following:

• Examination of the tumor.
• Resection margins.
• Lymph nodes.

Prognostic and treatment decisions are based on some of the following factors:

• Knowledge of histologic type.
• Tumor size and location.
• Involvement of pleura.
• Surgical margins.
• Status and location of lymph nodes by station.
• Tumor grade.
• Lymphovascular invasion.

At diagnosis, patients with NSCLC can be divided into the following three groups that reflect both the extent of the disease and the treatment approach:

1. Surgically resectable disease (generally stage I, stage II, and selected stage III tumors).
   • Has the best prognosis, which depends on a variety of tumor and host factors.
   • Patients with resectable disease who have medical contraindications to surgery are candidates for curative radiation therapy.
   • Postoperative cisplatin-based combination chemotherapy may provide a survival advantage for patients with resected stage II or stage IIIA NSCLC.
2. Locally (T3–T4) and/or regionally (N2–N3) advanced disease.
   • Has a diverse natural history.
   • Selected patients with locally advanced tumors may benefit from combined modality treatments.
   • Patients with unresectable or N2–N3 disease are treated with radiation therapy in combination with chemotherapy.
   • Selected patients with T3 or N2 disease can be treated effectively with surgical resection and either preoperative or postoperative chemotherapy or chemoradiation therapy.
3. Distant metastatic disease (includes distant metastases [M1] that were found at the time of diagnosis).
   • May be treated with radiation therapy or chemotherapy for palliation of symptoms of the primary tumor.
   • Patients with good performance status, women, and patients with distant metastases confined to a single site live longer than others.[2]
   • Platinum-based chemotherapy has been associated with short-term palliation of symptoms and with a survival advantage.
   • Currently, no single chemotherapy regimen can be recommended for routine use.
   • Patients previously treated with platinum combination chemotherapy may derive symptom control and survival benefit from docetaxel, pemetrexed, or epidermal growth factor receptor inhibitors.

Staging Evaluation

Evaluation of mediastinal lymph node metastasis

Surgical evaluation

Surgical staging of the mediastinum is considered standard if accurate evaluation of the nodal status is needed to determine therapy.

Accurate staging of the mediastinal lymph nodes provides important prognostic information.

Evidence (nodal status):

1. The association between survival and the number of examined lymph nodes during surgery for patients with stage I NSCLC treated with definitive surgical resection was assessed from the population-based Surveillance, Epidemiology, and End Results (SEER) database for the period from 1990 to 2000.[3] A total of 16,800 patients were included in the study.
   • The overall survival analysis for patients without radiation therapy demonstrated that in comparison with the reference group (one to four lymph nodes), patients with five to eight lymph nodes examined during surgery had a modest but statistically significant increase in survival, with a proportionate hazard ratio (HR) of 0.90 (95% confidence interval [CI], 0.84–0.97). For patients with 9 to 12 examined lymph nodes, the HR was 0.86 (95% CI, 0.79–0.95), and for patients with 13 to 16 examined lymph nodes, the HR was 0.78 (95% CI, 0.68–0.90). There appeared to be no incremental improvement after evaluating more than 16 lymph nodes. The corresponding results for lung cancer–specific mortality and for patients receiving radiation therapy were not substantially different.
   • These results indicate that patient survival following resection for NSCLC is associated with the number of lymph nodes evaluated during surgery. Because this is most likely the result of a reduction-of-staging error, namely, a decreased likelihood of missing positive lymph nodes with an increasing number of lymph nodes sampled, it suggests that an evaluation of nodal status should include 11 to 16 lymph nodes.

CT imaging

CT scanning is primarily used for determining the size of the tumor. The CT scan should extend inferiorly to include the liver and adrenal glands. MRI scans of the thorax and upper abdomen do not appear to yield advantages over CT scans.[4]

Evidence (CT scan):

1. A systematic review of the medical literature relating to the accuracy of CT scanning for noninvasive staging of the mediastinum in patients with lung cancer has been conducted. In the 35 studies published between 1991 and June 2006, 5,111 evaluable patients were identified. Almost all studies specified that CT scanning was performed following the administration of intravenous contrast material and that a positive test result was defined as the presence of one or more lymph nodes that measured larger than 1 cm on the short-axis diameter.[5]
   • The median prevalence of mediastinal metastasis was 28% (range, 18%–56%).
   • The pooled sensitivity and specificity of CT scanning for identifying mediastinal lymph node metastasis were 51% (95% CI, 47%–54%) for sensitivity and 86% (95% CI, 84%–88%) for specificity. Corresponding positive (3.4%) and negative (0.6%) likelihood ratios were provided.
2. The results from the systematic review are similar to those of a large meta-analysis that reported the median sensitivity and specificity of CT scanning for identifying malignant mediastinal nodes as 61% for sensitivity and 79% for specificity.[6]
3. An earlier meta-analysis reported an average sensitivity rate of 64% and specificity rate of 74%.[7]

18F-FDG PET scanning

The wider availability and use of 18F-FDG PET scanning for staging has modified the approach to staging mediastinal lymph nodes and distant metastases.

Randomized trials evaluating the utility of 18F-FDG PET scanning in potentially resectable NSCLC report conflicting results in terms of the relative reduction in the number of noncurative thoracotomies.

Although the current evidence is conflicting, 18F-FDG PET scanning may improve results of early-stage lung cancer by identifying patients who have evidence of metastatic disease that is beyond the scope of surgical resection and that is not evident by standard preoperative staging procedures.

Evidence (18F-FDG PET scan):

1. A systematic review, an expansion of a health technology assessment conducted in 2001 by the Institute for Clinical and Evaluative Sciences, evaluated the accuracy and utility of 18F-FDG PET scanning in the diagnosis and staging of lung cancer.[8] Through a systematic search of the literature, 12 evidence summary reports and 15 prospective studies of the diagnostic accuracy of 18F-FDG PET scanning were identified. 18F-FDG PET scanning appears to be superior to CT imaging for mediastinal staging in NSCLC. 18F-FDG PET scanning also appears to have high sensitivity and reasonable specificity for differentiating benign from malignant lesions as small as 1 cm.
2. A systematic review of the medical literature relating to the accuracy of 18F-FDG PET scanning for noninvasive staging of the mediastinum in patients with lung cancer identified 44 studies published between 1994 and 2006 with 2,865 evaluable patients.[5] The median prevalence of mediastinal metastases was 29% (range, 5%–64%). Pooled estimates of sensitivity and specificity for identifying mediastinal metastasis were 74% (95% CI, 69%–79%) for sensitivity and 85% (95% CI, 82%–88%) for specificity. Corresponding positive (4.9%) and negative (0.3%) likelihood ratios were provided for mediastinal staging with 18F-FDG PET scanning. These findings demonstrated that 18F-FDG PET scanning is more accurate than CT scanning for staging of the mediastinum in patients with lung cancer.

Cost effectiveness of 18F-FDG PET scanning

Decision analyses demonstrate that 18F-FDG PET scanning may reduce the overall costs of medical care by identifying patients with falsely negative CT scans in the mediastinum or otherwise undetected sites of metastases.[9-11] Studies concluded that the money saved by forgoing mediastinoscopy in 18F-FDG PET-positive mediastinal lesions was not justified because of the unacceptably high number of false-positive results.[9-11] A randomized study found that the addition of 18F-FDG PET scanning to conventional staging was associated with significantly fewer thoracotomies.[12] A second randomized trial evaluating the impact of 18F-FDG PET scanning on clinical management found that 18F-FDG PET scanning provided additional information regarding appropriate stage but did not lead to significantly fewer thoracotomies.[13]

Combination of CT imaging and 18F-FDG PET scanning

The combination of CT imaging and 18F-FDG PET scanning has greater sensitivity and specificity than CT imaging alone.[14]

Evidence (CT/18F-FDG PET scan):

1. If there is no evidence of distant metastatic disease on CT scan, 18F-FDG PET scanning complements CT scan staging of the mediastinum. Numerous nonrandomized studies of 18F-FDG PET scanning have evaluated mediastinal lymph nodes using surgery (i.e., mediastinoscopy and/or thoracotomy with mediastinal lymph node dissection) as the gold standard of comparison.
2. In a meta-analysis evaluating the conditional test performance of 18F-FDG PET scanning and CT scanning, the median sensitivity and specificity of 18F-FDG PET scans were reported as 100% for sensitivity and 78% for specificity in patients with enlarged lymph nodes.[6] 18F-FDG PET scanning is considered very accurate in identifying malignant nodal involvement when lymph nodes are enlarged. However, 18F-FDG PET scanning will falsely identify a malignancy in approximately one-fourth of patients with lymph nodes that are enlarged for other reasons, usually as a result of inflammation or infection.[15,16]
3. The median sensitivity and specificity of 18F-FDG PET scanning in patients with normal-sized mediastinal lymph nodes were 82% for sensitivity and 93% for specificity.[6] These data indicate that nearly 20% of patients with normal-sized lymph nodes but with malignant involvement had falsely negative 18F-FDG PET scan findings.

For patients with clinically operable NSCLC, the recommendation is for a biopsy of mediastinal lymph nodes that were found to be larger than 1 cm in shortest transverse axis on chest CT scan or were found to be positive on 18F-FDG PET scan. Negative 18F-FDG PET scanning does not preclude biopsy of radiographically enlarged mediastinal lymph nodes. Mediastinoscopy is necessary for the detection of cancer in mediastinal lymph nodes when the results of the CT scan and 18F-FDG PET scan do not corroborate each other.

Evaluation of brain metastasis

Patients at risk for brain metastases may be staged with CT or MRI scans. One study randomly assigned 332 patients with potentially operable NSCLC and no neurological symptoms to brain CT or MRI imaging to detect occult brain metastasis before lung surgery. MRI showed a trend towards a higher preoperative detection rate than CT scan (P= .069), with an overall detection rate of approximately 7% from pretreatment to 12 months after surgery.[17] Patients with stage I or stage II disease had a detection rate of 4% (i.e., eight detections out of 200 patients); however, individuals with stage III disease had a detection rate of 11.4% (i.e., 15 detections out of 132 patients). The mean maximal diameter of the brain metastases was significantly smaller in the MRI group. Whether the improved detection rate of MRI translates into improved outcome remains unknown. Not all patients are able to tolerate MRI, and for these patients contrast-enhanced CT scan is a reasonable substitute.

Evaluation of distant metastasis other than the brain

Numerous nonrandomized, prospective, and retrospective studies have demonstrated that 18F-FDG PET scanning seems to offer diagnostic advantages over conventional imaging in staging distant metastatic disease; however, standard 18F-FDG PET scans have limitations. 18F-FDG PET scans may not extend below the pelvis and may not detect bone metastases in the long bones of the lower extremities. Because the metabolic tracer used in 18F-FDG PET scanning accumulates in the brain and urinary tract, 18F-FDG PET scanning is not reliable for detection of metastases in these sites.[17]

The Revised International System for Staging Lung Cancer

The Revised International System for Staging Lung Cancer, based on information from a clinical database of more than 5,000 patients, was adopted in 2010 by the American Joint Committee on Cancer (AJCC) and the Union Internationale Contre le Cancer.[18,19] These revisions provide greater prognostic specificity for patient groups; however, the correlation between stage and prognosis predates the widespread availability of PET imaging.

AJCC Stage Groupings and TNM Definitions

The AJCC has designated staging by TNM (tumor, node, metastasis) classification to define NSCLC.[19]

Table 1. Definitions of TNM Occult Carcinomaa

Stage	TNM	Description
aReprinted with permission from AJCC: Lung. In: Amin MB, Edge SB, Greene FL, et al., eds.: AJCC Cancer Staging Manual. 8th ed. New York, NY: Springer, 2017, pp 431–56.
Occult carcinoma	TX, N0, M0	TX = Primary tumor cannot be assessed, or tumor proven by the presence of malignant cells in sputum or bronchial washings but not visualized by imaging or bronchoscopy.
		N0 = No regional lymph node metastasis.
		M0 = No distant metastasis.
T = primary tumor; N = regional lymph node; M = distant metastasis.

Table 2. Definitions of TNM Stage 0a

Stage	TNM	Description
T = primary tumor; N = regional lymph node; M = distant metastasis.
aReprinted with permission from AJCC: Lung. In: Amin MB, Edge SB, Greene FL, et al., eds.: AJCC Cancer Staging Manual. 8th ed. New York, NY: Springer, 2017, pp 431–56.
0	Tis, N0, M0	Tis = Carcinoma in situ; SCIS =Squamous cell carcinoma in situ; AIS: Adenocarcinoma in situ; Adenocarcinoma with pure lepidic pattern, ≤3 cm in greatest dimension.
		N0 = No regional lymph node metastasis.
		M0 = No distant metastasis.

Table 3. Definitions of TNM Stages IA1, IA2, IA3, and IBa

Stage	TNM	Description
T = primary tumor; N = regional lymph node; M = distant metastasis.
aReprinted with permission from AJCC: Lung. In: Amin MB, Edge SB, Greene FL, et al., eds.: AJCC Cancer Staging Manual. 8th ed. New York, NY: Springer, 2017, pp 431–56.
IA1	T1mi, N0, M0	T1 = Tumor ≤3 cm in greatest dimension, surrounded by lung or visceral pleura, without bronchoscopic evidence of invasion more proximal than the lobar bronchus (i.e., not in the main bronchus).
		–T1mi = Minimally invasive adenocarcinoma: Adenocarcinoma (≤3 cm in greatest dimension) with a predominantly lepidic pattern and ≤5 mm invasion in greatest dimension.
		N0 = No regional lymph node metastasis.
		M0 = No distant metastasis.
	T1a, N0, M0	T1 = Tumor ≤3 cm in greatest dimension, surrounded by lung or visceral pleura, without bronchoscopic evidence of invasion more proximal than the lobar bronchus (i.e., not in the main bronchus).
		–T1mi = Minimally invasive adenocarcinoma: adenocarcinoma (≤3 cm in greatest dimension) with a predominantly lepidic pattern and ≤5 mm invasion in greatest dimension.
		–T1a = Tumor ≤1 cm in greatest dimension. A superficial, spreading tumor of any size whose invasive component is limited to the bronchial wall and may extend proximal to the main bronchus also is classified as T1a, but these tumors are uncommon.
		N0 = No regional lymph node metastasis.
		M0 = No distant metastasis.
IA2	T1b, N0, M0	T1 = Tumor ≤3 cm in greatest dimension, surrounded by lung or visceral pleura, without bronchoscopic evidence of invasion more proximal than the lobar bronchus (i.e., not in the main bronchus).
		–T1mi = Minimally invasive adenocarcinoma: adenocarcinoma (≤3 cm in greatest dimension) with a predominantly lepidic pattern and ≤5 mm invasion in greatest dimension.
		–T1a = Tumor ≤1 cm in greatest dimension. A superficial, spreading tumor of any size whose invasive component is limited to the bronchial wall and may extend proximal to the main bronchus also is classified as T1a, but these tumors are uncommon.
		–T1b = Tumor >1 cm but ≤2 cm in greatest dimension.
		N0 = No regional lymph node metastasis.
		M0 = No distant metastasis.
IA3	T1c, N0, M0	T1 = Tumor ≤3 cm in greatest dimension, surrounded by lung or visceral pleura, without bronchoscopic evidence of invasion more proximal than the lobar bronchus (i.e., not in the main bronchus).
		–T1mi = Minimally invasive adenocarcinoma: adenocarcinoma (≤3 cm in greatest dimension) with a predominantly lepidic pattern and ≤5 mm invasion in greatest dimension.
		–T1a = Tumor ≤1 cm in greatest dimension. A superficial, spreading tumor of any size whose invasive component is limited to the bronchial wall and may extend proximal to the main bronchus also is classified as T1a, but these tumors are uncommon.
		–T1b = Tumor >1 cm but ≤2 cm in greatest dimension.
		–T1c = Tumor >2 cm but ≤3 cm in greatest dimension.
		N0 = No regional lymph node metastasis.
		M0 = No distant metastasis.
IB	T2a, N0, M0	T2 = Tumor >3 cm but ≤5 cm or having any of the following features: involves the main bronchus regardless of distance to the carina, but without involvement of the carina; invades visceral pleura (PL1 or PL2); associated with atelectasis or obstructive pneumonitis that extends to the hilar region, involving part or all of the lung. T2 tumors with these features are classified as T2a if ≤4 cm or if the size cannot be determined and T2b if >4 cm but ≤5 cm.
		–T2a = Tumor >3 cm but ≤4 cm in greatest dimension.
		N0 = No regional lymph node metastasis.
		M0 = No distant metastasis.

Table 4. Definitions of TNM Stages IIA and IIBa

Stage	TNM	Description
T = primary tumor; N = regional lymph node; M = distant metastasis.
aReprinted with permission from AJCC: Lung. In: Amin MB, Edge SB, Greene FL, et al., eds.: AJCC Cancer Staging Manual. 8th ed. New York, NY: Springer, 2017, pp 431–56.
IIA	T2b, N0, M0	T2 = Tumor >3 cm but ≤5 cm or having any of the following features: involves the main bronchus regardless of distance to the carina, but without involvement of the carina; invades visceral pleura (PL1 or PL2); associated with atelectasis or obstructive pneumonitis that extends to the hilar region, involving part or all of the lung. T2 tumors with these features are classified as T2a if ≤4 cm or if the size cannot be determined and T2b if >4 cm but ≤5 cm.
		–T2a = Tumor >3 cm but ≤4 cm in greatest dimension.
		–T2b = Tumor >4 cm but ≤5 cm in greatest dimension.
		N0 = No regional lymph node metastasis.
		M0 = No distant metastasis.
IIB	T1a, N1, M0	T1 = Tumor ≤3 cm in greatest dimension, surrounded by lung or visceral pleura, without bronchoscopic evidence of invasion more proximal than the lobar bronchus (i.e., not in the main bronchus).
		–T1a = Tumor ≤1 cm in greatest dimension. A superficial, spreading tumor of any size whose invasive component is limited to the bronchial wall and may extend proximal to the main bronchus also is classified as T1a, but these tumors are uncommon.
		N1 = Metastasis in ipsilateral peribronchial and/or ipsilateral hilar lymph nodes and intrapulmonary nodes, including involvement by direct extension.
		M0 = No distant metastasis.
	T1b, N1, M0	T1 = Tumor ≤3 cm in greatest dimension, surrounded by lung or visceral pleura, without bronchoscopic evidence of invasion more proximal than the lobar bronchus (i.e., not in the main bronchus).
		–T1a = Tumor ≤1 cm in greatest dimension. A superficial, spreading tumor of any size whose invasive component is limited to the bronchial wall and may extend proximal to the main bronchus also is classified as T1a, but these tumors are uncommon.
		–T1b = Tumor >1 cm but ≤2 cm in greatest dimension.
		N1 = Metastasis in ipsilateral peribronchial and/or ipsilateral hilar lymph nodes and intrapulmonary nodes, including involvement by direct extension.
		M0 = No distant metastasis.
	T1c, N1, M0	T1 = Tumor ≤3 cm in greatest dimension, surrounded by lung or visceral pleura, without bronchoscopic evidence of invasion more proximal than the lobar bronchus (i.e., not in the main bronchus).
		–T1a = Tumor ≤1 cm in greatest dimension. A superficial, spreading tumor of any size whose invasive component is limited to the bronchial wall and may extend proximal to the main bronchus also is classified as T1a, but these tumors are uncommon.
		–T1b = Tumor >1 cm but ≤2 cm in greatest dimension.
		–T1c = Tumor >2 cm but ≤3 cm in greatest dimension.
		N1 = Metastasis in ipsilateral peribronchial and/or ipsilateral hilar lymph nodes and intrapulmonary nodes, including involvement by direct extension.
		M0 = No distant metastasis.
	T2a, N1, M0	T2 = Tumor >3 cm but ≤5 cm or having any of the following features: involves the main bronchus regardless of distance to the carina, but without involvement of the carina; invades visceral pleura (PL1 or PL2); associated with atelectasis or obstructive pneumonitis that extends to the hilar region, involving part or all of the lung. T2 tumors with these features are classified as T2a if ≤4 cm or if the size cannot be determined and T2b if >4 cm but ≤5 cm.
		–T2a = Tumor >3 cm but ≤4 cm in greatest dimension.
		N1 = Metastasis in ipsilateral peribronchial and/or ipsilateral hilar lymph nodes and intrapulmonary nodes, including involvement by direct extension.
		M0 = No distant metastasis.
	T2b, N1, M0	T2 = Tumor >3 cm but ≤5 cm or having any of the following features: involves the main bronchus regardless of distance to the carina, but without involvement of the carina; invades visceral pleura (PL1 or PL2); associated with atelectasis or obstructive pneumonitis that extends to the hilar region, involving part or all of the lung. T2 tumors with these features are classified as T2a if ≤4 cm or if the size cannot be determined and T2b if >4 cm but ≤5 cm.
		–T2a = Tumor >3 cm but ≤4 cm in greatest dimension.
		–T2b = Tumor >4 cm but ≤5 cm in greatest dimension.
		N1 = Metastasis in ipsilateral peribronchial and/or ipsilateral hilar lymph nodes and intrapulmonary nodes, including involvement by direct extension.
		M0 = No distant metastasis.
	T3, N0, M0	T3 = Tumor >5 cm but ≤7 cm in greatest dimension or directly invading any of the following: parietal pleura (PL3), chest wall (Including superior sulcus tumors), phrenic nerve, parietal pericardium; or separate tumor nodule(s) in the same lobe as the primary.
		N0 = No regional lymph node metastasis.
		M0 = No distant metastasis.

Table 5. Definitions of TNM Stages IIIA, IIIB, and IIICa

Stage	TNM	Description
T = primary tumor; N = regional lymph node; M = distant metastasis.
aReprinted with permission from AJCC: Lung. In: Amin MB, Edge SB, Greene FL, et al., eds.: AJCC Cancer Staging Manual. 8th ed. New York, NY: Springer, 2017, pp 431–56.
IIIA	T1a, N2, M0	T1 = Tumor ≤3 cm in greatest dimension, surrounded by lung or visceral pleura, without bronchoscopic evidence of invasion more proximal than the lobar bronchus (i.e., not in the main bronchus).
		–T1a = Tumor ≤1 cm in greatest dimension. A superficial, spreading tumor of any size whose invasive component is limited to the bronchial wall and may extend proximal to the main bronchus also is classified as T1a, but these tumors are uncommon.
		N2 = Metastasis in ipsilateral mediastinal and/or subcarinal lymph node(s).
		M0 = No distant metastasis.
	T1b, N2, M0	T1 = Tumor ≤3 cm in greatest dimension, surrounded by lung or visceral pleura, without bronchoscopic evidence of invasion more proximal than the lobar bronchus (i.e., not in the main bronchus).
		–T1a = Tumor ≤1 cm in greatest dimension. A superficial, spreading tumor of any size whose invasive component is limited to the bronchial wall and may extend proximal to the main bronchus also is classified as T1a, but these tumors are uncommon.
		–T1b = Tumor >1 cm but ≤2 cm in greatest dimension.
		N2 = Metastasis in ipsilateral mediastinal and/or subcarinal lymph node(s).
		M0 = No distant metastasis.
	T1c, N2, M0	T1 = Tumor ≤3 cm in greatest dimension, surrounded by lung or visceral pleura, without bronchoscopic evidence of invasion more proximal than the lobar bronchus (i.e., not in the main bronchus).
		–T1a = Tumor ≤1 cm in greatest dimension. A superficial, spreading tumor of any size whose invasive component is limited to the bronchial wall and may extend proximal to the main bronchus also is classified as T1a, but these tumors are uncommon.
		–T1b = Tumor >1 cm but ≤2 cm in greatest dimension.
		–T1c = Tumor >2 cm but ≤3 cm in greatest dimension.
		N2 = Metastasis in ipsilateral mediastinal and/or subcarinal lymph node(s).
		M0 = No distant metastasis.
	T2a, N2, M0	T2 = Tumor >3 cm but ≤5 cm or having any of the following features: involves the main bronchus regardless of distance to the carina, but without involvement of the carina; invades visceral pleura (PL1 or PL2); associated with atelectasis or obstructive pneumonitis that extends to the hilar region, involving part or all of the lung. T2 tumors with these features are classified as T2a if ≤4 cm or if the size cannot be determined and T2b if >4 cm but ≤5 cm.
		–T2a = Tumor >3 cm but ≤4 cm in greatest dimension.
		N2 = Metastasis in ipsilateral mediastinal and/or subcarinal lymph node(s).
		M0 = No distant metastasis.
	T2b, N2, M0	T2 = Tumor >3 cm but ≤5 cm or having any of the following features: involves the main bronchus regardless of distance to the carina, but without involvement of the carina; invades visceral pleura (PL1 or PL2); associated with atelectasis or obstructive pneumonitis that extends to the hilar region, involving part or all of the lung. T2 tumors with these features are classified as T2a if ≤4 cm or if the size cannot be determined and T2b if >4 cm but ≤5 cm.
		–T2a = Tumor >3 cm but ≤4 cm in greatest dimension.
		–T2b = Tumor >4 cm but ≤5 cm in greatest dimension.
		N2 = Metastasis in ipsilateral mediastinal and/or subcarinal lymph node(s).
		M0 = No distant metastasis.
	T3, N1, M0	T3 = Tumor >5 cm but ≤7 cm in greatest dimension or directly invading any of the following: parietal pleura (PL3), chest wall (including superior sulcus tumors), phrenic nerve, parietal pericardium; or separate tumor nodule(s) in the same lobe as the primary.
		N1 = Metastasis in ipsilateral peribronchial and/or ipsilateral hilar lymph nodes and intrapulmonary nodes, including involvement by direct extension.
		M0 = No distant metastasis.
	T4, N0, M0	T4 = Tumor >7 cm or tumor of any size invading one or more of the following: diaphragm, mediastinum, heart, great vessels, trachea, recurrent laryngeal nerve, esophagus, vertebral body, or carina; separate tumor nodule(s) in an ipsilateral lobe different from that of the primary.
		N0 = No regional lymph node metastasis.
		M0 = No distant metastasis.
	T4, N1, M0	T4 = Tumor >7 cm or tumor of any size invading one or more of the following: diaphragm, mediastinum, heart, great vessels, trachea, recurrent laryngeal nerve, esophagus, vertebral body, or carina; separate tumor nodule(s) in an ipsilateral lobe different from that of the primary.
		N1 = Metastasis in ipsilateral peribronchial and/or ipsilateral hilar lymph nodes and intrapulmonary nodes, including involvement by direct extension.
		M0 = No distant metastasis.
IIIB	T1a, N3, M0	T1 = Tumor ≤3 cm in greatest dimension, surrounded by lung or visceral pleura, without bronchoscopic evidence of invasion more proximal than the lobar bronchus (i.e., not in the main bronchus).
		–T1a = Tumor ≤1 cm in greatest dimension. A superficial, spreading tumor of any size whose invasive component is limited to the bronchial wall and may extend proximal to the main bronchus also is classified as T1a, but these tumors are uncommon.
		N3 = Metastasis in contralateral mediastinal, contralateral hilar, ipsilateral or contralateral scalene, or supraclavicular lymph node(s).
		M0 = No distant metastasis.
	T1b, N3, M0	T1 = Tumor ≤3 cm in greatest dimension, surrounded by lung or visceral pleura, without bronchoscopic evidence of invasion more proximal than the lobar bronchus (i.e., not in the main bronchus).
		–T1a = Tumor ≤1 cm in greatest dimension. A superficial, spreading tumor of any size whose invasive component is limited to the bronchial wall and may extend proximal to the main bronchus also is classified as T1a, but these tumors are uncommon.
		–T1b = Tumor >1 cm but ≤2 cm in greatest dimension.
		N3 = Metastasis in contralateral mediastinal, contralateral hilar, ipsilateral or contralateral scalene, or supraclavicular lymph node(s).
		M0 = No distant metastasis.
	T1c, N3, M0	T1 = Tumor ≤3 cm in greatest dimension, surrounded by lung or visceral pleura, without bronchoscopic evidence of invasion more proximal than the lobar bronchus (i.e., not in the main bronchus).
		–T1a = Tumor ≤1 cm in greatest dimension. A superficial, spreading tumor of any size whose invasive component is limited to the bronchial wall and may extend proximal to the main bronchus also is classified as T1a, but these tumors are uncommon.
		–T1b = Tumor >1 cm but ≤2 cm in greatest dimension.
		–T1c = Tumor >2 cm but ≤3 cm in greatest dimension.
		N3 = Metastasis in contralateral mediastinal, contralateral hilar, ipsilateral or contralateral scalene, or supraclavicular lymph node(s).
		M0 = No distant metastasis.
	T2a, N3, M0	T2 = Tumor >3 cm but ≤5 cm or having any of the following features: involves the main bronchus regardless of distance to the carina, but without involvement of the carina; invades visceral pleura (PL1 or PL2); associated with atelectasis or obstructive pneumonitis that extends to the hilar region, involving part or all of the lung. T2 tumors with these features are classified as T2a if ≤4 cm or if the size cannot be determined and T2b if >4 cm but ≤5 cm.
		–T2a = Tumor >3 cm but ≤4 cm in greatest dimension.
		N3 = Metastasis in contralateral mediastinal, contralateral hilar, ipsilateral or contralateral scalene, or supraclavicular lymph node(s).
		M0 = No distant metastasis.
	T2b, N3, M0	T2 = Tumor >3 cm but ≤5 cm or having any of the following features: involves the main bronchus regardless of distance to the carina, but without involvement of the carina; invades visceral pleura (PL1 or PL2); associated with atelectasis or obstructive pneumonitis that extends to the hilar region, involving part or all of the lung. T2 tumors with these features are classified as T2a if ≤4 cm or if the size cannot be determined and T2b if >4 cm but ≤5 cm.
		–T2a = Tumor >3 cm but ≤4 cm in greatest dimension.
		–T2b = Tumor >4 cm but ≤5 cm in greatest dimension.
		N3 = Metastasis in contralateral mediastinal, contralateral hilar, ipsilateral or contralateral scalene, or supraclavicular lymph node(s).
		M0 = No distant metastasis.
	T3, N2, M0	T3 = Tumor >5 cm but ≤7 cm in greatest dimension or directly invading any of the following: parietal pleura (PL3), chest wall (including superior sulcus tumors), phrenic nerve, parietal pericardium; or separate tumor nodule(s) in the same lobe as the primary.
		N2 = Metastasis in ipsilateral mediastinal and/or subcarinal lymph node(s).
		M0 = No distant metastasis.
	T4, N2, M0	T4 = Tumor >7 cm or tumor of any size invading one or more of the following: diaphragm, mediastinum, heart, great vessels, trachea, recurrent laryngeal nerve, esophagus, vertebral body, or carina; separate tumor nodule(s) in an ipsilateral lobe different from that of the primary.
		N2 = Metastasis in ipsilateral mediastinal and/or subcarinal lymph node(s).
		M0 = No distant metastasis.
IIIC	T3, N3, M0	T3 = Tumor >5 cm but ≤7 cm in greatest dimension or directly invading any of the following: parietal pleura (PL3), chest wall (including superior sulcus tumors), phrenic nerve, parietal pericardium; or separate tumor nodule(s) in the same lobe as the primary.
		N3 = Metastasis in contralateral mediastinal, contralateral hilar, ipsilateral or contralateral scalene, or supraclavicular lymph node(s).
		M0 = No distant metastasis.
	T4, N3, M0	T4 = Tumor >7 cm or tumor of any size invading one or more of the following: diaphragm, mediastinum, heart, great vessels, trachea, recurrent laryngeal nerve, esophagus, vertebral body, or carina; separate tumor nodule(s) in an ipsilateral lobe different from that of the primary.
		N3 = Metastasis in contralateral mediastinal, contralateral hilar, ipsilateral or contralateral scalene, or supraclavicular lymph node(s).
		M0 = No distant metastasis.

Table 6. Definitions of TNM Stages IV, IVA, and IVBa

Stage	TNM	Description
T = primary tumor; N = regional lymph node; M = distant metastasis.
aReprinted with permission from AJCC: Lung. In: Amin MB, Edge SB, Greene FL, et al., eds.: AJCC Cancer Staging Manual. 8th ed. New York, NY: Springer, 2017, pp 431–56.
IV	Any T, Any N, M1	TX = Primary tumor cannot be assessed, or tumor proven by the presence of malignant cells in sputum or bronchial washings but not visualized by imaging or bronchoscopy.
		T0 = No evidence of primary tumor.
		Tis = carcinoma in situ; SCIS = squamous cell carcinoma in situ; AIS = adenocarcinoma in situ: Adenocarcinoma with pure lepidic pattern, ≤3 cm in greatest dimension.
		T1 = Tumor ≤3 cm in greatest dimension, surrounded by lung or visceral pleura, without bronchoscopic evidence of invasion more proximal than the lobar bronchus (i.e., not in the main bronchus).
		–T1mi = Minimally invasive adenocarcinoma: Adenocarcinoma (≤3 cm in greatest dimension) with a predominantly lepidic pattern and ≤5 mm invasion in greatest dimension.
		–T1a = Tumor ≤1 cm in greatest dimension. A superficial, spreading tumor of any size whose invasive component is limited to the bronchial wall and may extend proximal to the main bronchus also is classified as T1a, but these tumors are uncommon.
		–T1b = Tumor >1 cm but ≤2 cm in greatest dimension.
		–T1c = Tumor >2 cm but ≤3 cm in greatest dimension.
		T2 = Tumor >3 cm but ≤5 cm or having any of the following features: involves the main bronchus regardless of distance to the carina, but without involvement of the carina; invades visceral pleura (PL1 or PL2); associated with atelectasis or obstructive pneumonitis that extends to the hilar region, involving part or all of the lung. T2 tumors with these features are classified as T2a if ≤4 cm or if the size cannot be determined and T2b if >4 cm but ≤5 cm.
		–T2a = Tumor >3 cm but ≤4 cm in greatest dimension.
		–T2b = Tumor >4 cm but ≤5 cm in greatest dimension.
		T3 = Tumor >5 cm but ≤7 cm in greatest dimension or directly invading any of the following: parietal pleura (PL3), chest wall (including superior sulcus tumors), phrenic nerve, parietal pericardium; or separate tumor nodule(s) in the same lobe as the primary.
		T4 = Tumor >7 cm or tumor of any size invading one or more of the following: diaphragm, mediastinum, heart, great vessels, trachea, recurrent laryngeal nerve, esophagus, vertebral body, or carina; separate tumor nodule(s) in an ipsilateral lobe different from that of the primary.
		NX = Regional lymph nodes cannot be assessed.
		N0 = No regional lymph node metastasis.
		N1 = Metastasis in ipsilateral peribronchial and/or ipsilateral hilar lymph nodes and intrapulmonary nodes, including involvement by direct extension.
		N2 = Metastasis in ipsilateral mediastinal and/or subcarinal lymph node(s).
		N3 = Metastasis in contralateral mediastinal, contralateral hilar, ipsilateral or contralateral scalene, or supraclavicular lymph node(s).
		M1 = Distant metastasis.
IVA	Any T, Any N, M1a	Any T = See T descriptions above in Any T, Any N, M1.
		Any N = See N descriptions above in Any T, Any N, M1.
		M1 = Distant metastasis.
		–M1a = Separate tumor nodule(s) in a contralateral lobe; tumor with pleural or pericardial nodules or malignant pleural or pericardial effusion. Most pleural (pericardial) effusions with lung cancer are a result of the tumor. In a few patients, however, multiple microscopic examinations of pleural (pericardial) fluid are negative for tumor, and the fluid is nonbloody and not an exudate. If these elements and clinical judgment dictate that the effusion is not related to the tumor, the effusion should be excluded as a staging descriptor.
	Any T, Any N, M1b	Any T = See T descriptions above in Any T, Any N, M1.
		Any N = See N descriptions above in Any T, Any N, M1.
		M1 = Distant metastasis.
		–M1a = Separate tumor nodule(s) in a contralateral lobe; tumor with pleural or pericardial nodules or malignant pleural or pericardial effusion. Most pleural (pericardial) effusions with lung cancer are a result of the tumor. In a few patients, however, multiple microscopic examinations of pleural (pericardial) fluid are negative for tumor, and the fluid is nonbloody and not an exudate. If these elements and clinical judgment dictate that the effusion is not related to the tumor, the effusion should be excluded as a staging descriptor.
		–M1b = Single extrathoracic metastases in a single organ (including involvement of a single nonregional node).
IVB	Any T, Any N, M1c	Any T = See T descriptions above in Any T, Any N, M1.
		Any N = See N descriptions above in Any T, Any N, M1.
		M1 = Distant metastasis.
		–M1a = Separate tumor nodule(s) in a contralateral lobe; tumor with pleural or pericardial nodules or malignant pleural or pericardial effusion. Most pleural (pericardial) effusions with lung cancer are a result of the tumor. In a few patients, however, multiple microscopic examinations of pleural (pericardial) fluid are negative for tumor, and the fluid is nonbloody and not an exudate. If these elements and clinical judgment dictate that the effusion is not related to the tumor, the effusion should be excluded as a staging descriptor.
		–M1b = Single extrathoracic metastases in a single organ (including involvement of a single nonregional node).
		–M1c = Multiple extrathoracic metastases in a single organ or in multiple organs.

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