Integrated Colorectal Care • Long Island • New York

What is Colon Cancer Screening?

Colorectal cancer is both preventable and curable when found early. Colorectal cancer is prevented by removing precancerous colon polyps. It is cured if cancerous change is found early and is surgically removed before the cancer cells spread to other parts of the body. The National Polyp Study showed in its surveillance program that individuals who had their polyps removed experienced a 90% reduction in the incidence of colorectal cancer. The few patients in the study who did develop colorectal cancer had their cancer discovered at early, surgically or endoscopically curable stages. Since most colon polyps and early cancers are silent (produce no symptoms), it is important to do screening and surveillance for colon cancer in patients without symptoms or signs of the polyps or cancers.

The life-time risk for an adult American to develop colorectal cancer is approximately 6%. Fecal (stool) occult blood tests and flexible sigmoidoscopic examinations are the recommended screening tests for these individuals at average risk for developing colorectal cancer. These tests are designed to detect and to prompt removal of precancerous polyps and identify early cancers in order to decrease mortality from colorectal cancer. Stool testing and flexible sigmoidoscopy are affordable, easy to perform, and comfortable for healthy individuals.

Many individuals are at higher than average risk for developing colon cancer because of a family history of colon cancer, history of chronic ulcerative colitis, rare hereditary colon cancer syndromes, or a history of colon polyps or cancer. Periodic surveillance colonoscopies are recommended for these individuals to remove precancerous polyps, and/or to detect early cancers. Such testing will typically be recommended to begin at an earlier age than it will for those with average risk.

Patients with history of colon polyps

Patients with history of colon polyps often develop polyps subsequently. Therefore, periodic surveillance colonoscopies are recommended. In individuals with only precancerous polyps that are completely removed, the usual recommendation is to repeat the colonoscopy after 3 years. If the colonoscopy at 3 years shows no recurrence of polyps, then the interval between subsequent colonoscopies is extended to 5 years.

Sometimes, doctors are not confident that all polyps have been completely removed. Examples include individuals with multiple pre-cancerous polyps, polyps that are technically difficult to completely excise, or less than optimal visualization of the colon due to inadequate cleansing of the colon. Under these circumstances, the decision regarding the interval between surveillance colonoscopies is best arrived at jointly between the patient and the doctor.

Patients with history of colorectal cancer

Individuals who have undergone colon cancer surgery are at higher risk of developing another colon cancer in the future. It usually is recommended that they undergo a repeat colonoscopy after 6 to 12 months and every 3 years thereafter. Early detection and treatment of future polyps and early cancers can significantly improve chances of survival. The annual testing of stool for occult blood continues.

Patients with Ulcerative Colitis

Patients with long standing Ulcerative Colitis also have a higher risk of developing colorectal cancer. The risk of developing colon cancer is proportional to the duration of disease and to the extent of colon involved by colitis. Thus, patients with chronic Ulcerative Colitis involving the entire colon should have a colonoscopy every 1 to 2 years after having the colitis for 10 years or more. During the procedure, biopsies are taken from the colon to look for early, microscopic precancerous changes in the cells. If precancerous cells are detected, colonoscopy is repeated 3 months later. If still present, doctors may discuss with the patient the benefits of surgically removing the colon to prevent colon cancer. If the Colitis is limited to only the left colon, the same surveillance program is started 15 years after the onset of colitis.

Patients with a Family history of colorectal cancer

Colorectal cancer may run in families. Colon cancer risk to an individual is even higher if more than one immediate family member (parents, siblings or children) has had colorectal cancer, and/or the family member developed the cancer at a young age (less than 55). Under these circumstances, it is recommended that individuals undergo a colonoscopy every three years starting at an age that is 7-10 years younger than the age at which the family member who developed colorectal cancer at the youngest age developed his or her cancer.

If only one immediate family member developed colorectal cancer at an advanced age, the colon cancer risk to the individual is still higher than average but not as high as if two immediate family members developed colorectal cancer or if a family member developed colorectal cancer at an early age. Whether and when to perform screening colonoscopies in these individuals are best decided jointly by the individuals and their doctors.

Summary of colon cancer screening

Colon cancer is preventable and curable. Colon cancer is preventable by removing precancerous colon polyps, and it is curable if early cancer is surgically removed before cancer spreads to other parts of the body. Therefore, if screening and surveillance programs were practiced universally, there would be a major reduction in the incidence and mortality of colorectal cancer.Ongoing genetic research will help doctors better understand the genetic basis of colorectal cancer formation. Genetic blood tests and tests for premalignant cells in stool may also have a role in colorectal cancer screening. Regardless of what new screening methods become available, you should remember to discuss colon cancer screening and/or surveillance as it relates to your situation.