Colon and Rectal Cancer Overview

Colorectal cancer begins in the lining of the colon or rectum.

A cancerous tumor can metastasize to other parts of the body. Growth and metastases occur over years.

When it is benign the tumor can grow but will not spread. Colorectal cancer is the third leading cancer among both sexes, and the second most common cancer by and large.

The 5 year survival rate is 65%. However, if the cancer is localized the 5 year survival is 90%. If the cancer has spread to lymph nodes and surrounding tissue, the 5 year survival is 71%. When the cancer has spread to distant parts of the body like the lung or liver, the 5 year survival rate is 13%. However, if a patient has only one or a few tumors that have spread, surgery to remove these tumors can eliminate colorectal cancer and improve the survival rate.

The colon and rectum are part of the large intestines, where waste is processed and released.

The first 5-6 of intestines are the Colon, and the last 6 inches are the rectum. Thus, the early diagnosis and treatment of colorectal cancer, the better the outcome.

Thus, colorectal cancer screening can prevent or provide early diagnosis of polyps and colorectal cancer. The tests to screen for colorectal cancer include:

  • This test allows the physician to visualize the rectum and colon, with the use of a flexible, lighted tube. During this procedure the physician can remove polyps and retrieve tissue for examination- a biopsy.
  • This procedures checks the lower colon for polyps and cancer.
  • A CT colonography or virtual colonoscopy and is often used where a patient cannot tolerate anesthesia, used during a colonoscopy.
  • Other tests include a Fecal occult blood test which will find blood in the feces, which can be a sign of polyps or cancer. Barium enema is not as efficient as other screenings. Finally, a stool DNA test is used to find colon cancer and may be used to decide whether a colonoscopy is needed.

Screening is recommended with a sigmoidoscopy every five years, and a colonoscopy every 10 years up to the age of 75.

Most colorectal cancers begin as polyps. Most polyps are noncancerous. 95% of colorectal cancers are adenocarcinomas, that start in the glands in the lining of the colon and rectum.


Polyps can be noncancerous , precancerous or cancerous. Colon cancer often begins as a non-cancerous polyp. If not removed, it can develop into cancer. Most often polyps are found during a colonoscopy and when found are removed and sent to a lab to determine if they are cancerous. Removal of polyps can prevent colorectal cancer.

Most polyps are easily identified during a colonoscopy because they create a bulge in the wall of the colon. But about 10% of polyps are flat and difficult to discover during a colonoscopy, and tend to create a high risk of cancer.


  • Age, as we age, the risk goes up, most colorectal cancer is diagnosed at 72.
  • Males risk is slightly higher than females
  • Type 2 diabetes
  • Family history- when colon cancer affects first degree relatives it is considered hereditary, and is usually diagnosed before the age of 60. A family history doubles the risk for colon cancer. The risk increases if other family members are diagnosed or when a first degree relative is diagnosed when younger than 60.
  • People with a history of colon, ovarian, or uterine cancers are more likely to develop colon cancer.
  • African Americans have the highest rate of non- heredity colorectal cancer and is a leading cause of death among African Americans. Since they are more likely to be diagnosed with colon cancer, it is recommended that African Americans begin screening colonoscopy at age 45.
  • Physical inactivity and obesity increase the risk.
  • Dietary research suggest that obesity increases the risk, and eating red meat and processed meats specifically increases risk
  • Smoking – smokers are more likely to die from colorectal cancer.

Ways to prevent colorectal cancer include:

Studies suggest that aspirin and other NSAIDS can reduce the risk of developing polyps in people with history of polyps or colon cancer.

  • Diets rich in fruits and vegetables and low red meat intake can help reduce the risk.
  • Taking calcium supplements and Vitamin D3 reduces the risk.

Signs and symptoms of colorectal cancer:

While these signs and symptoms are also recommended for noncancerous conditions, when these symptoms are recent, severe, long lasting and change over time it is important to see your physician.

  • A change in bowl habits, like diarrhea, constipation or a sensation that you need to have a bowel movement.
  • Rectal bleeding, bright red or dark blood in the stool
  • Discomfort such as frequent gas, bloating, fullness and cramps
  • Unexplained weight loss
  • Fatigue
  • Unexplained iron deficiency anemia

If cancer is diagnosed the surgical removal of the tumor and some healthy tissue is imperative. In addition, radiation therapy, chemotherapy, and targeted therapies may also be used.

The general surgeons at BASS Medical Group are board-certified and experienced in colorectal cancer diagnosis and treatment. They are Fellows of the American College of Surgeons, and are part of our multi-specialty group which is dedicated to your health and well being. Choosing the right surgeon to perform your surgery is one of the most important decisions a patient can make. Our offices are in San Francisco and the East Bay, California, to serve our patients. Find the location convenient to you. Then call BASS Medical Group to schedule a consultation to discuss your concerns, get answers to your questions and receive professional, quality care.