domingo, 4 de noviembre de 2018

Pulmonary Resection in Lung Cancer

Download PDF Copy

By Liji Thomas, MDReviewed by Yolanda Smith, B.Pharm.

Pulmonary resection is the first line of treatment of stage I and II non-small cell lung cancer (NSCLC). It is also important as part of the management of stage IIIA. In early stages of NSCLC, the surgery focuses on diagnosis, staging and resection of the entire tumor. Pneumonectomy and lobectomy carry a mortality rate in hospital of up to 4% and 8% percent respectively.

Types of Pulmonary Resection

Different portions of the lung are removed during the diverse procedures that make up pulmonary resection, including:

Pneumonectomy refers to removal of the lung affected with cancer.

Lobectomy refers to the removal of the diseased lobe, ligation of the bronchovascular structures and removal of the lymph nodes in the hilum and mediastinum on the same side. It is the gold standard for pulmonary resection in lung cancer.

Sublobar resection refers to the removal of less than an entire lobe of a lung, within anatomical or non-anatomical boundaries. Their advantages include lower mortality rates and comparable complication rates or lung function when set against a lobectomy. Currently, these are advised when a patient is too ill or whose lung reserve is too low to tolerate lobectomy.

Wedge resections, also known as non-anatomical sublobar resections are performed in patients too ill for lobectomy, for small tumors which are peripherally located and cross anatomical boundaries, or those with multiple primary NSCLC tumors. Wide margins of excision should be provided to ensure tumor-negative margins and lymph node removal is mandatory.

Segmentectomy refers to the removal of a lung segment beginning with bronchovascular ligation and anatomical dissection, followed by a mediastinal lymph node sampling as for lobectomy. Anatomical segmentectomy has comparable survival and recurrence rates to lobectomy, when performed for tumors smaller than 3 cm. For larger tumors, it is associated with higher recurrence rates.

Video-assisted thoracoscopic surgery (VATS)

This approach uses 2-4 ports and requires an incision 5-8 cm long. VATS lobectomy involves the same procedure as open thoracotomy, and the same type of operative complications may be expected, though at a lower frequency. Benefits include:

Lowering of the complication rate
Less pain
Earlier recovery
Shorter hospitalization
Higher quality of life for the patient
Better respiratory function
Better adjuvant therapy
Better immune function

Robotic surgery

Robotic surgery for pulmonary resection shares many of the benefits of VATS and some additional advantages, such as:

The need for smaller incisions without any access incision
Less pain
Binocular visualization of the operative site
CO2 insufflation allows for a more complete collapse of the lung and therefore a larger field of operation
Higher mobility within the field of surgery with the use of jointed instruments, providing easier dissection
Shorter hospital stays and cost reduction

Requirements for surgery in lung cancer

At least three conditions must be met before surgery is carried out for lung cancer:

The patient should agree to surgery
The tumor should be one of the NSCLC types
It should be surgically resectable, which means there should be no clinically significant spread to the mediastinum or distant areas, confirmed by CT, PET or endoscopy of the bronchi and mediastinum

Fitness for pulmonary resection

The patient’s fitness for surgery is determined by several factors, including:

Patient age
Patient cardiovascular fitness
Nutritional status
Functional status
Respiratory function

A low BMI, advanced age, weight loss over 10% of previous weight, and low serum albumin levels are indicators of an unfavorable prognosis, marking either disseminated or advanced disease or a higher risk of delayed recovery from surgery.

Preoperative criteria for pulmonary resection

Testing lung function

Pulmonary function should be thoroughly tested before making a decision on pulmonary resection. This includes the following:

Spirometry to measure the forced expiratory volume (FEV1), and the forced vital capacity (FVC), after optimizing the patient’s respiratory function with bronchodilator therapy. FEV1/FVC ratio, as well as various flow rates and residual volume is determined. Alveolar/capillary function may also be assessed by the diffusion capacity. In combination with the lung volume removed, which is best assessed by a post-surgical ventilation scan, these parameters allow for an accurate prediction of the post-operative respiratory function.

Ventilation-perfusion scanning following the inhalation of radioactive xenon and the intravenous infusion of technetium-labeled particles demonstrates the areas of reduced ventilation and/or perfusion, showing how much each lung contributes to the total pulmonary function.

Cardiovascular fitness

Exercise testing assesses the cardiopulmonary reserve and oxygen delivery. It may be simply tested by finding how many flights of stairs one can climb at a stretch.

Cardiopulmonary exercise testing (CPET) is the best way to accurately predict post-operative pulmonary function. A treadmill or exercise bicycle may be used with constant ECG, spirometric and oxygen consumption/carbon dioxide production monitoring. This helps determine many important parameters such as exercise testing and maximal oxygen consumption, peak heart rate and respiratory gas exchange ratio.

Arterial blood gas analysis may offer hints of an unfavorable post-operative recovery, in case there is low oxygen saturation and desaturation of over 4% following exercise.

Predictors of mortality

A preoperative FEV1 above 1.5 or 2 liters indicates a favorable operative prognosis for a lobectomy or pneumonectomy respectively. For very short patients, females or those of advanced age, if it indicates 80% or more of the predicted value, pneumonectomy is considered safe.

A DLCO falling below 80% and 60% of predicted value indicates a higher risk of lung complications and death respectively.

Research is currently being conducted to investigate factors that determine the likelihood of positive and negative and positive outcomes with surgery, which will in turn help to decrease mortality and morbidity rates. This will help to identify patients who will most benefit from intervention and assist in the decisions for treatment. Possible factors may include the type of tumor, advancement of the tumor growth and other health conditions that affect the patient.