What are the other Names for this Condition? (Also known as/Synonyms)

• Gastrointestinal Stromal Neoplasm
• Gastrointestinal Stromal Sarcoma
• GIST (Gastrointestinal Stromal Tumor)

What is Gastrointestinal Stromal Tumor? (Definition/Background Information)

• A Gastrointestinal Stromal Tumor (GIST) is a type of tumor that occurs in the gastrointestinal tract. The most common location of this tumor is the stomach, or the small intestine
• The origin of the tumor is uncertain. Some researchers believe that these tumors originate from a special type of cells that are present in the gastrointestinal tract, called the interstitial cells of Cajal (ICCs)
• GIST can either be benign or malignant, depending on various characteristics. Also, most tumors occur randomly, while some originate due to a family history of the condition
• It is found that between 50-70% of the tumors occur in the stomach and between 20-30% in the small intestine. Other less common sites, include the rectum, esophagus, and colon
• Often, these tumors remain undiagnosed. Hence, some believe that the incidence of GIST is higher than the estimated numbers
• The standard treatment mode involves a surgical excision and removal of the entire tumor followed by chemotherapy. However, GIST outcome depends on the type of tumor and whether it has metastasized

Who gets Gastrointestinal Stromal Tumor? (Age and Sex Distribution)

• Gastrointestinal Stromal Tumors usually occur in adults. The affected age range is between 40-70 years
• Males are affected slightly more than females; although, some studies have indicated no gender preferences
• The global incidence of GIST is around 1 in 50,000. Some racial predilection is observed, though it is not yet verified

What are the Risk Factors for Gastrointestinal Stromal Tumor? (Predisposing Factors)

• A majority of Gastrointestinal Stromal Tumors are sporadic and no known risk factors have been identified
• In familial GIST cases, genetic factors are responsible. Individuals with a familial history of the condition are highly susceptible to these tumors. In such cases, GIST is acquired as an autosomal dominant condition

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases ones chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Gastrointestinal Stromal Tumor? (Etiology)

• Genetic mutations in specific genes cause Gastrointestinal Stromal Tumors; mutations in two genes account for a majority of the cases. Mutation in these genes, result in an uncontrolled growth of cells, leading to tumor formation
• It is estimated that 80% of such tumors are caused by a mutation in the KIT gene; around 10% of diagnosed cases, caused by a mutation in the PDGFRA gene. The reminder of the tumors occurs, due to mutation in certain other genes
• There are two types of Gastrointestinal Stromal Tumors:
  • Sporadic tumors
  • Familial tumors
• Both, familial and sporadic tumors are caused by mutations in the KIT and PDGFRA genes. These genes are responsible for making proteins that are involved in cell growth and cell death
• In a minority of the cases, the mutations are inherited from parents and in such cases, are called familial GIST
• In familial GIST, mutations are inherited in an autosomal dominant pattern, which means that only one copy of the mutated gene in each cell is enough to increase an individual’s chance of developing Gastrointestinal Stromal Tumors
• In sporadic cases of GIST, there is usually a single tumor, whereas in familial type of GISTs, multiple tumors may occur

What are the Signs and Symptoms of Gastrointestinal Stromal Tumor?

The signs and symptoms of Gastrointestinal Stromal Tumors vary according to the size of the tumors. Generally, small-sized tumors may show no signs or symptoms (unlike larger-sized tumors). The signs and symptoms when present may include:

• Pain
• Abdominal swelling
• Nausea and vomiting
• Loss of appetite, weight loss
• Bleeding (leading to anemia, resulting in weakness and tiredness)
• Bleeding into the intestinal tract, may result in dark, black, and tarry stools
• Vomiting of blood, if bleeding occurs into the throat or stomach
• Discoloration of skin causing dark skin patches; these dark patches may occur anywhere in the body
• Urticaria pigmentosa (a skin disorder) is known to occur in patients with GISTs. In this disorder, the individual has skin lesions that are characterized by raised patches of itchy brownish skin. These may be either localized (confined to certain parts of the body), or present all over the body

How is Gastrointestinal Stromal Tumor Diagnosed?

A diagnosis of Gastrointestinal Stromal Tumor may include

• Physical exam with evaluation of medical history
• CT scan, MRI scan of abdomen and pelvic region
• PET scan
• Abdominal, endoscopic ultrasonography
• Radiographic studies of the abdomen, including barium swallow/enema
• Blood analysis - total blood count, serum study
• Liver function test
• Differential diagnosis, to eliminate other tumor types is considered, before arriving at a definitive diagnosis

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Gastrointestinal Stromal Tumor?

Complications due to Gastrointestinal Stromal Tumors could include:

• Large-sized tumors may cause: Obstruction, hemorrhaging of the gastrointestinal tract, perforation of bowel, inward collapse of the intestine resulting in torsion of bowel wall
• Complications are also dependent on the site and severity of the tumor. It is easier to treat the primary tumor, but after metastasis occurs, the treatment can be very challenging
• Frequently, metastasis of the tumor occurs in the liver and peritoneum (thin lining membrane in the abdomen)
• High risk of tumor recurrence after surgery have been reported in aggressive tumors
• Damage of vital nerves, blood vessels, and surrounding structures, during surgery
• Surgery-related post-surgical infections, ulceration, lung and heart related complications may occur
• Side effects from chemotherapy (toxicity) and radiation therapy can also occur

How is Gastrointestinal Stromal Tumor Treated?

Treatment measures of Gastrointestinal Stromal Tumor include:

• Wide surgical excision of GIST with removal of the entire lesion, which is followed by a course of chemotherapy, is the standard treatment mode employed. The surgical excision may be performed using laparoscopic surgical techniques
• Non-surgical intervention includes chemotherapy and/or radiotherapy - these modalities are generally used to shrink the tumor, if possible, before an invasive surgical procedure is planned and performed
• Arterial or chemo-embolization is used to provide temporary relief from the symptoms, and reduce blood loss during a surgical procedure
• When GIST is at an inaccessible location, or is unsafe for surgical intervention, non-invasive procedures are adopted
• Post-operative care is important: A minimum activity level is to be ensured, until the surgical wound heals
• Follow-up care with regular screening and check-ups are important

How can Gastrointestinal Stromal Tumor be Prevented?

• Current medical research have not established a way of preventing Gastrointestinal Stromal Tumor
• Regular medical screening at periodic intervals with blood tests, scans, and physical examinations, are mandatory for those who have already endured the tumor, due to its high metastasizing potential and possibility of recurrence. Often several years of active vigilance is necessary

What is the Prognosis of Gastrointestinal Stromal Tumor? (Outcomes/Resolutions)

• Gastrointestinal Stromal Tumors are tumors of varying malignancy potential; some are malignant, while other may be benign. The long-term prognosis depends on a combination of factors, such as:
  • Age of the individual
  • Tumor stage at detection
  • Tumor size, type, and location
  • Whether it has spread around the area, or to other distant locations
  • How receptive it is to treatment
• However, the two key determinants of the outcome of GIST are - the tumor size and cell division rate (mitotic rate) of the tumor. Small tumor size (less than 5 cm) and very low mitotic activity, project the best outcomes
• The long-term prognosis is guarded, when the tumor has metastasized to other regions. The survival period is around 10-20 months for most individuals with metastasis. In individuals without metastasis, the 5-year survival rate is between 30-60%

Additional and Relevant Useful Information for Gastrointestinal Stromal Tumor:

• Most tumors are detected incidentally, while the individual is undergoing a diagnostic procedure or scan, for some other ailment. Statistically, the average tumor size has been found to be 4 cm or less
• Around 5000 Gastrointestinal Stromal Tumors are diagnosed in the United States, every year
• The pathology report of the tumor issued by a pathologist, indicates the aggressiveness of the tumor