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About Rectal Cancer

The rectum and the colon make up the large intestine, or large bowel. The rectum makes up the last six inches of the large intestine and connects the colon to the anus. Colon cancer and rectal cancer are often grouped together (colorectal cancer), because they share many of the same characteristics and are often treated similarly. Most rectal cancers start as a growth, called a polyp, on the inner lining of the colon or rectum. While not all polyps progress to cancer, some can change into cancer over time, usually over the course of many years. Polyps may be small and produce few, if any, symptoms. For this reason, doctors recommend regular screening tests to help prevent colon cancer by identifying and removing polyps before they turn into cancer.

There are various factors that can increase the risk of a polyp developing into cancer such as a polyp larger than one centimeter, more than three polyps found, and if dysplasia, or the presence of abnormal cells, is seen in a polyp after removal.

Types of polyps include:

  • Adenomatous polyps (adenomas) sometimes change into cancer. Because of this, adenomas are called a pre-cancerous condition. The 3 types of adenomas are tubular, villous, and tubulovillous.
  • Hyperplastic polyps and inflammatory polyps are more common, but in general they are not pre-cancerous. Some people with large (more than 1 cm) hyperplastic polyps might need colorectal cancer screening with colonoscopy more often to monitor the polyp.
  • Sessile serrated polyps (SSP) and traditional serrated adenomas (TSA) are often treated like adenomas because they have a higher risk of colorectal cancer

Types of Rectal Cancer

Most rectal cancers are adenocarcinomas, which means the cancer starts in the cells that make the mucus that lubricates the inside of the colon and rectum.

Other, less common types of tumors can also develop in the colon and rectum and include:

  • Carcinoid tumors develop from special hormone-making cells in the intestine.
  • Gastrointestinal stromal tumors (GISTs) develop from special cells in the wall of the colon called the interstitial cells of Cajal. Some are benign (non-cancerous). These tumors can be found anywhere in the digestive tract but are not common in the colon.
  • Lymphomas are cancers of immune system cells. They mostly develop in lymph nodes, but they can also develop in the colon, rectum, or other organs. Information on lymphomas of the digestive system can be found in non-Hodgkin lymphoma.
  • Sarcomas can develop in blood vessels, muscle layers, or other connective tissues in the wall of the colon and rectum. Sarcomas of the colon or rectum are rare.
  • Melanoma is a cancer that develops from cells called melanocytes, which give skin its color. While melanoma usually starts in the skin, there are also small numbers of melanocytes in the mucosa, which is a tissue that lines various parts of the body, including the anus and rectum. Melanoma of the colon or rectum develops in the mucosa and is extremely rare.

Symptoms of Rectal Cancer:

  • A change in bowel habits, such as diarrhea, constipation, or more-frequent bowel movements
  • A feeling that your bowel doesn’t empty completely
  • Dark maroon or bright red blood in stool
  • Narrow stool
  • Abdominal pain
  • Unintended weight loss
  • Weakness or fatigue
  • Change in appetite

Risk Factors for Rectal Cancer

African Americans are at higher risk for developing rectal cancer than other races.

Other common risk factors for rectal cancer include:

  • Family history of colon or rectal cancer
  • A history of cancer of the colon, rectum, or ovary
  • A history of high-risk adenomas, or colorectal polyps that are one centimeter or larger in size or that have cells that look abnormal
  • A history of inflammatory bowel disease
  • A history of chronic ulcerative colitis or Crohn’s disease
  • Inherited changes in certain genes that increase the risk of familial adenomatous polyposis (FAP) or Lynch syndrome (hereditary nonpolyposis colorectal cancer)
  • Older age, usually over the age of 50, though it can occur at any age
  • Excessive alcohol consumption
  • Smoking
  • Lack of physical activity
  • Obesity

Treating Rectal Cancer at UT Health Austin

Treatment requires accurate diagnosis and a care plan tailored to the specific type of tumor, the tumor’s location, and the overall needs of the patient. The different behavior of different tumor types helps drive decisions about treatment, which may include combinations of surgery, radiation therapy, and chemotherapy.

Care Team Approach

At UT Health Austin, we take a multidisciplinary approach to your care. This means you will benefit from the expertise of multiple specialists across a variety of disciplines. Your care team will include medical oncologists, surgical oncologists, radiation oncologists, pathologists, radiologists, oncofertility specialists, onco-psychiatrists, genetic counselors, physical therapists, dietitians, social workers, and more as well as other members of the CaLM Care Team who work together to help you get back to the things in your life that matter most to you. We also collaborate with our colleagues at the Dell Medical School and The University of Texas at Austin to utilize the latest research, diagnostic, and treatment techniques, allowing us to identify and utilize new therapies to improve cancer treatment outcomes. We are committed to communicating and coordinating your care with your other healthcare providers to ensure that we are providing you with comprehensive, whole-person care.

Learn More About Your Care Team

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