What is Colorectal Cancer?
Although colon and rectal cancers are often grouped together they are staged and treated differently. The colon and rectum are the last two parts of the gastrointestinal tract. After digestion in the stomach and small intestine, food then reaches the colon (large intestine). The colon absorbs water and salt from the food remains.
After passing through the colon, the food matter reaches the rectum as stool. The rectum is a reservoir for the stool until it passes through the anus during a bowel movement. (Anal cancers are different from colorectal cancers with their own staging and treatment).
Colorectal cancers are the fourth most common non-skin cancers diagnosed annually in the U.S. and the second most common cause of cancer death after lung cancer.
Preventing Colorectal Cancer:
The best way to prevent colorectal cancer is to eat a healthy diet with a variety of fruits, vegetables and whole grains. Many studies have confirmed an association of the typical Western diet, rich in fat and low in fiber, with increased risk of colon cancer. It’s not exactly known why a high-fat, low-fiber diet increases risk but it is believed that such a diet affects the microbes in the colon or causes inflammation to the colon contributing to cancer risk.
Ways to reduce risk of colorectal cancer:
- Eat healthy! A diet rich in a variety of fruits, vegetables and whole grain increases vitamins, minerals, fiber and antioxidants.
- Limit alcohol: Limit the amount of alcohol to one drink a day for women and two drinks a day for men.
- Quit smoking: Stopping smoking lowers risk of developing many cancers and also risk of heart disease, stroke, lung disease and many others. Your doctor can help with ways to quit smoking.
- Exercise! A regular exercise routine with at least 30 minutes of exercise on most days can reduce risk. You may need to talk to your doctor before starting an exercise program.
- Weight loss: Maintaining an optimal weight through a healthy diet and exercise reduces cancer risks. If you need to lose weight, ask your doctor about safe ways to get back to a healthy weight.
- Screenings! Recommended screenings such as colonoscopy can actually help prevent colorectal cancers!
- Aspirin? Non-steroidal anti-inflammatory drugs (NSAIDS), such as aspirin, have been shown to lower risk of colon polyps and cancer. However, these medications can be dangerous or life-threatening if not taken appropriately. Consult with you doctor before starting an NSAID.
Less common colorectal cancers related to genetic syndromes have different prevention and screening recommendations. These genetically related colon cancers can present before age 40. If you have a strong history of cancers in your family make sure to discuss with your doctor.
Colorectal Cancer Screening:
Screening is the process of detecting cancer early in people without symptoms of the disease. Getting regular colorectal cancer screenings is a powerful way of preventing colorectal cancer. This is because colorectal cancers typically start as polyps and it usually takes about 10-15 years for a polyp to develop into a cancer. Regular screening can detect and remove polyps before they become cancers.
It is recommended to begin regular screenings at age 45. There are several types of screening tests but colonoscopies are most common. Preparing for colonoscopy can be inconvenient and uncomfortable but it is needed for the test to be effective. Typically, preparation involves avoiding solid food the day before test, adjusting medications and taking laxatives to empty your colon.
If you are in good health and with a life expectancy of at least 10 years, it is recommended to continue colorectal cancer screening through age of 75. If you are aged 76 through 85, talk with your doctor about continuing screenings based on preference, life expectancy, overall health and previous screening history. Interval of regular screening varies for some but general guidelines say to repeat colonoscopies every 10 years.
Screening recommendations are different for those with a strong family history of colorectal polyps or cancer and those diagnosed with an inherited cancer syndrome. If either of these applies to you make sure you talk to your doctor about screening.
Colorectal Cancer Treatment:
Although colon and rectal cancers are often grouped together they are treated differently depending on the stage and location of the cancer. Treatments can be local therapies or systemic therapies.
Local therapy means treating the tumor without affecting other parts of the body. Local therapies include surgery and radiation therapy. They are useful for early stage colon and rectal cancers, but may be used in other situations as well. Systemic therapies are drugs that travel throughout the body. Systemic therapy can be given by mouth or through the bloodstream and include chemotherapy, targeted therapy and immune therapy.
Stage I-III and some stage IV colon cancers are managed by surgical removal with or without chemotherapy.
- Stage I cancers are treated by partial removal of the colon. Some very favorable cancers are removed at time of colonoscopy.
- Stage II cancers are managed by partial removal of the colon. Depending on risk factors and your health, it may be recommended to receive systemic therapy after surgery.
- Stage III cancers are managed by partial removal of the colon followed by systemic therapy. If you are not healthy enough for surgery, systemic therapy and radiation therapy may be options.
- Stage IV cancers are managed by systemic therapy. Some favorable stage IV cancers may be treated more aggressively with surgery. Surgery may also be performed to create a diversion for stool (colostomy) if the cancer affects digestion.
Stage I-III rectal cancers are managed by surgical removal with or without radiation therapy. The type of surgery depends on the location of cancer in the rectum: If the cancer is too close to the anus, surgery may require a permanent colostomy. Radiation reduces risk of permanent colostomy, reduces risk of cancer returning and improves survival. Systemic therapy is often given with radiation therapy.
- Stage I cancers are removed by surgery. Very early tumors can sometimes be removed during colonoscopy. Others are removed with microsurgery through the anus or more commonly with removal of the rectum.
- Stage II cancers are most commonly managed by radiation combined with chemotherapy followed by surgical removal of the rectum. Surgery is often followed by additional chemotherapy.
- Stage III cancers are managed similar to stage II cancers.
- Stage IV cancers are managed by systemic therapy. Some favorable stage IV cancers may be treated more aggressively with surgery, systemic therapy and radiation. The timing of systemic therapy and radiation therapy varies.