Gastrointestinal Cancer: Symptoms, Signs and Causes

The signs and symptoms of GI cancer often vary from one patient to another. Each type of GI cancer may have different sets of symptoms. Becoming aware of the different gastrointestinal cancer symptoms and the possible causes is important, as it helps one seek the right care at the right time.

The exact cause of GI cancer is unknown; however, certain lifestyle-related and non-lifestyle-related factors have been found to increase the risk of GI cancer.

Who is Mainly Affected by Gastrointestinal Cancer?

Different types of GI cancer may have different sets of gastrointestinal symptoms and causes. Those with poor diet habits, such as a heavy intake of processed foods and a low intake of fruits and vegetables; those who smoke; those with H. pylori infection; and those with chronic gastritis, have a higher risk of stomach cancer.

Esophageal cancer risk is high among those who have chronic gastroesophageal reflux disease, underlying medical conditions such as obesity, Barrett's esophagus, and bile acid reflux, who drink alcohol, and who have a history of radiation therapy in the chest.

Colon cancer risk is high among those with a history of colon polyps, inflammatory bowel disease, and inherited syndromes, such as Lynch syndrome, an unhealthy lifestyle, obesity, and excessive alcohol intake.

Liver cancer risk is high among those with underlying medical conditions, such as chronic hepatitis infection, diabetes, cirrhosis, non-alcoholic fatty liver disease, inherited liver diseases (Wilson's disease and hemochromatosis), aflatoxin exposures, and excessive consumption of alcohol.

Almost half of the carcinoid tumors occur in the GIT. Melanomas of the GIT are usually asymptomatic but may cause symptoms in some cases. Common signs of intestinal leiomyosarcomas include GI bleeding and abdominal pain.

What are the symptoms of gastrointestinal cancer?

Not all patients experience the same gastrointestinal cancer symptoms. Some may not experience any early signs, while others do. Also, these symptoms may vary depending on the type of GI cancer. In general, the following are the important gastrointestinal cancer symptoms:

Causes of Gastrointestinal cancer

Some of the possible causes of gastrointestinal cancers are:

When to see an Oncologist?

People should visit an oncologist if they experience nausea, vomiting, loss of appetite, abdominal discomfort, blood in stools, sudden changes in bowel habits, constipation, diarrhea, heartburn, and unexplained weight loss.


The commonly observed gastrointestinal cancer symptoms are indigestion, heartburn, diarrhea and constipation, loss of appetite, weight loss without any apparent reason, and blood in stools. The causes of gastrointestinal cancers include viral infections, H.pylori infections, inflammatory bowel disease, obesity, smoking, and excessive alcohol consumption.

Frequently Asked Questions

Most of the gastrointestinal cancer symptoms overlap among different cancer types. However, some symptoms are specific; for instance, fresh blood in stools may indicate anal cancer, while black tarry stools may suggest stomach cancer. Persistent heartburn may indicate esophageal cancer.

People with a family history of gastrointestinal cancer are more likely to develop this condition. Further, certain inherited genetic conditions increase the risk of gastrointestinal cancer. The following are some of the important inherited genetic conditions that are reported to increase the risk of GI cancer:

  • Lynch syndrome
  • Hereditary breast and ovarian cancer
  • Polyposis
  • Hereditary diffuse gastric cancer syndrome
  • Peutz-Jeghers syndrome

The gastrointestinal cancer symptoms observed may vary according to the type of cancer and its stage. Gastrointestinal cancer symptoms are usually limited to the GI tract in the early stages. However, in advanced stages, gastrointestinal cancer symptoms may be experienced in other organs, such as the lungs or bones.

Certain conditions, such as the presence of polyps, inflammatory bowel disease, chronic GERD, Barrett’s esophagus, etc., may increase the risk of gastrointestinal cancer.

Gastric cancer may occur at any age. However, people between the ages of 50 and 70 are most commonly affected.

GI cancer can be detected using various tests, such as upper GI endoscopy, colonoscopy, imaging tests, blood tests, and biopsy.