Rectum

Rectal cancer

Rectal cancer is cancer that begins in the rectum. The rectum is the last few inches of the large intestine. It begins at the end of the last section of your colon and ends when it reaches the short, narrow passage to the anus.

Cancer inside the rectum (rectal cancer) and cancer in the colon (colon cancer) are often referred to together as “colorectal cancer”.

Although rectal and colon cancers are similar in many ways, their treatments are quite different. The main reason for this is that the rectum sits in a narrow space that is barely separated from other organs and structures. The narrow space can perform surgery to remove the rectal cancer complex.

In the past, long-term survival was rare for people with rectal cancer even after comprehensive treatment. Thanks to advances in treatment over the past few decades, rectal cancer survival rates have greatly improved.

The symptoms

Signs and symptoms of rectal cancer include:

• Change in bowel habits such as diarrhea, constipation, or more frequent bowel movements
• Dark maroon or bright red blood in the stool
• Narrow stools
• A feeling that your bowels are not completely emptied
• Abdominal pain
• Unexplained weight loss
• Weakness or fatigue

When to see a doctor

Make an appointment with your doctor if you have persistent symptoms that worry you.

Reasons

Rectal cancer begins when healthy cells in the rectum develop changes (mutations) in their DNA. A cell’s DNA contains instructions that tell a cell what to do.

The changes tell cells to grow uncontrollably and continue living after healthy cells die. The accumulating cells can form a tumor. Over time, cancer cells can grow and invade and destroy nearby healthy tissue. And cancerous cells can break down and travel (metastasize) to other parts of the body.

For most rectal cancers, it is not clear what causes the mutations that cause the cancer to occur.

Inherited gene mutations that increase the risk of colon and rectal cancer

In some families, gene mutations that are passed from parents to children increase the risk of colorectal cancer. These mutations are found in only a small percentage of rectal cancers. Some genes linked to colorectal cancer increase the risk of developing the disease, but do not make it inevitable.

Two well-defined genetic colorectal cancer syndromes are:

• Lynch syndrome. Lynch syndrome, also known as hereditary non-polyposis colorectal cancer (HNPCC), increases the risk of colon cancer and other cancers. People with Lynch syndrome tend to develop colon cancer before the age of 50.
• Familial adenomatous polyposis (FAP). FAP is a rare disease that causes thousands of polyp in the lining of your colon and rectum. People with untreated FAP have a significantly increased risk of developing colon or rectal cancer before the age of 40.

Genetic testing can detect these and other rarer inherited colorectal cancer syndromes. If you are concerned about your family’s colon cancer history, talk to your doctor whether your family history indicates that you are at risk for these conditions.

Risk factors

The factors that can increase the risk of rectal cancer are the same as those that increase the risk of colon cancer. Colorectal cancer risk factors include:

• Senile. Colorectal cancer can be diagnosed at any age, but most people with this type of cancer are over the age of 50. Colorectal cancer rates increase in people under 50, but doctors do not know why.
• African-American descent. People of African descent born in the United States are at higher risk of colorectal cancer than people of European descent.
• A personal history of colorectal cancer or polyps. Your risk of colorectal cancer is higher if you have already had rectal cancer, colon cancer, or adenomatous polyps.
• Inflammatory bowel disease. Chronic inflammatory diseases of the colon and rectum, such as ulcerative colitis and Crohn’s disease, increase your risk of colorectal cancer.
• Hereditary syndromes that increase the risk of rectal cancer. Genetic syndromes passed down through your family’s generations can increase your risk of colon and rectal cancer, including FAP and Lynch syndrome.
• Family history of colorectal cancer. You’re more likely to develop colorectal cancer if you have a parent, sibling, or child with colon or rectal cancer.
• Eating a diet low in vegetables. Colorectal cancer may be associated with a diet low in vegetables and high in red meat, especially when the meat is burned or cooked well.
• Very little exercise. You are more likely to develop colorectal cancer if you are sedentary. Regular physical activity can reduce your risk of cancer.
• Diabetes. People with uncontrolled type 2 diabetes may have an increased risk of colorectal cancer.
• Obesity. Obese people have a higher risk of colorectal cancer than people thought to be at a healthy weight.
• To smoke. Colorectal cancer risk may increase in people who smoke.
• To drink alcohol. Regular