jueves, 6 de septiembre de 2018

Gastrointestinal Stromal Tumor (GIST) Treatment

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By Angela Betsaida B. Laguipo, BSNReviewed by Susha Cheriyedath, MSc

Cancer happens when the cells in the body grow and produce out of control. Gastrointestinal stromal tumor (GIST) is a type of cancer that occurs in the gastrointestinal tract, particularly in the stomach and small intestine.

Overview of Gastrointestinal Stromal Tumor

Gastrointestinal stromal tumor (GIST) is a tumor or soft tissue sarcoma that occurs in the digestive system. Most commonly found in the small intestine and stomach, GIST is a condition wherein abnormal cells develop in the tissues of the digestive system.

Usually, the cancer cells stem from the special cells in the wall of the gastrointestinal tract called the interstitial cells of Cajal (ICC). These cells control and manage body processes such as digesting food. In some cases, they’re dubbed as pacemakers of the GI tract since they control the muscles to move food through the intestines.

Gastrointestinal stromal tumors can be either benign (noncancerous) or malignant (cancerous). These tumors are most common in the small intestine and stomach, but can also be found anywhere in the GI tract.

When the GIST is small, it may cause no symptoms and it can grow slowly. However, individuals with larger GISTs may need to seek medical attention since they can suffer from the signs and symptoms of the condition. The signs and symptoms may include blood in the stool, vomiting of blood, stomach pain, anemia or low red blood cell count, feeling bloated, nausea, vomiting, unexplained weight loss, problems with swallowing, and loss of appetite.

Treating a Gastrointestinal Stromal Tumor

Before treating the GIST, doctors usually request various diagnostic procedures to determine if there is a tumor, how big is it, and its location. These tests are used to examine the GI tract to detect and diagnose the stromal tumor.

The diagnostic procedures performed include physical examination, CT scan, magnetic resonance imaging (MRI) scan, and endoscopic ultrasound and biopsy. In case a cancer or tumor is found, the doctors may request further examination such as an immunohistochemistry to determine the different types of cancer. Another test commonly requested is the mitotic rate, which measures how fast the cancer cells are growing and dividing.

After diagnosing the tumor, the doctor can recommend the following treatment options.

Surgery

All large and symptomatic gastrointestinal stromal tumors should be removed surgically unless they’re too big or have affected many organs. Surgery is the main treatment for GISTs that haven’t spread to surrounding tissues and organs. The ultimate goal of surgery is to eradicate all of cancer.

For small tumors, they’re removed along with a tiny area of normal tissues that surround it. GISTs do not spread to the lymph nodes, making it unnecessary to remove lymph nodes near the tumor. Larger tumors, on the other hand, may need to be removed, including parts of the digestive tract affected by it.

Targeted Drug Therapy

One important fact about GISTs is that they do not respond to conventional chemotherapy. However, thanks to a better understanding of the disease process, drugs have been developed to interrupt the tumor spread. As a result, these drugs have greatly improved the prognosis of people with GISTs.

Targeted drug therapy has been a recommended treatment option for GISTs. These include drugs such as Imatinib (Gleevec), Sunitinib (Sutent), and Regorafenib (Stivarga). Imatinib is the first line of drug used to prevent the recurrence of GIST after surgery. The drug targets both the KIT and PDGFRA proteins, blocking their ability to trigger the growth and division of tumor cells.

Sunitinib (Sutent) is a drug that can be useful in treating GIST. Usually, it’s used if Imatinib is no longer working or the patient can’t tolerate the side effects of the drug. Just like Imatinib, Sunitinib targets the KIT and PDGFRA proteins, and other proteins not targeted by Imatinib. Lastly, Regorafenib (Stivarga) can be used for GIST treatment if both the drugs, Imatinib and Sunitinib, have stopped working. Regorafenib can slow down the growth of the tumor and at the same time, shrink the tumor.

Radiation Therapy

Radiation therapy involves the use of high-energy X-rays to kill cancer cells. However, though this treatment is used in treating GIST, it is not very helpful. Hence, it’s not used often. However, radiation therapy can be used to relieve symptoms such as bone pain or to stop bleeding. Also, radiation therapy may damage both tumor and healthy cells. The common side effects include mild skin reactions, fatigue, abdominal pain, and loose bowel movement.