This year alone the American Cancer Society estimates that there will be over 112,000 new cases of colon cancer and 41,420 new cases of rectal cancer in the United States. Combined, they will cause about 52,180 deaths. Cancer of the colon and rectum is a very common disease and now ranks as the third most common cancer found in men and women in this country.
Cancer arising in the colon or rectum is referred to as colorectal cancer. The key to the successful treatment of this disease lies in early detection and no where is this more evident than in the fact that the death rate from colorectal cancer has been going down for the past 15 years.
In most cases, colorectal cancers develop slowly over a period of several years. We now know that most of these cancers begin as a polyp––a growth of tissue that starts in the lining of the bowel. These polyps may be benign or may over time transform into cancers. An adenoma is a type of polyp with an increased risk of becoming cancerous. Removing the polyp early may prevent it from becoming cancerous and is a key step in reducing the incidence of colorectal cancers.
While we do not know the precise etiology of all colorectal cancers, there are certain known risk factors. These include age greater than 50, a history of inflammatory bowel disease such as Ulcerative Colitis or Crohn's Disease, and a history of adenomatous polyps. In addition, approximately 15% of all cases of colorectal cancer are hereditary and may be seen at younger ages.
Race and ethnicity are important risk factors that must be taken into account as well. African Americans, for example, have the highest incidence of colorectal cancer in the United States. Persons of Jewish descent from Eastern Europe (Ashkenazi Jews) carry the highest risk of developing colorectal cancer of any ethnicity in the world due to a genetic mutation.
Other preventable risk factors in the development of colorectal cancers include a diet rich in animal fat, high alcohol intake and a lack of exercise. Obesity itself also increases one's chances of developing cancer while smoking can increase this risk by as much as 40%. Diabetics have a 30% increased risk of developing colorectal cancer. They also tend to have a worse prognosis after diagnosis.
The importance of early detection can not be understated and modern tests include a simple stool blood test, endoscopic evaluation of the colon and or rectum using a flexible sigmoidoscope or colonoscopy or simple x–rays such as a barium enema. Radiologists have also developed "virtual" non–invasive colonoscopy using CT scans. American Cancer Society Colorectal Cancer Screening Guidelines are as follows for both men and women at age 50.
- Annual stool blood test or
- Flexible sigmoidoscopy every 5 years or
- Annual stool blood test plus flexible sigmoidoscopy every 5 years
- Double contrast barium enema every 5 years or
- Colonoscopy every 10 years
Symptoms of colorectal cancer are often absent but may include a change in bowel habits such as diarrhea, constipation, or narrowing of the stool that lasts for more than a few days. Other nonspecific symptoms may include cramping abdominal pain, fatigue and malaise. Rectal bleeding is a hallmark sign which warrants immediate evaluation.
Treatment of colon and rectal cancers is often very complex and involves a multi–disciplinary team approach. Because every patient's disease is different it must be individualized based on the extent of the disease, the patient's age and other medical conditions. Standard treatments include surgery, chemotherapy ("chemo") and radiation therapy.
Early stage tumors can often be excised surgically with no need for further therapies. Unfortunately however, most cancers are not detected at a very early stage and thus require combination therapy. Much research has been done in the field of oncology looking at regimens of chemotherapy and radiation given either before or after surgery. Chemotherapy is usually administered intravenously on certain days during daily radiation therapy. Advances in medical oncology have led to the discovery of more effective chemotherapy drugs. Some of the more common chemo drugs used include 5–FU, Oxaliplatin, and Capecitabine. Pre–medications given before chemo to reduce side effects have greatly decreased the incidence of nausea and vomiting as well as improved other treatment related complications such as fatigue by helping to improve anemia and reductions in white blood cells.
Technological advances in tumor target identification and image guidance have propelled radiation oncology forward as a powerful tool in the fight against colon and rectal cancer. Today radiation oncologists use multiple different imaging modalities to help pinpoint tumors and use complex computer generated treatment plans to maximize the dose of radiation within a tumor while at the same time being able to spare normal surrounding organs. This "selective" delivery of dose allows doctors to be able to further escalate the dose of radiation within a tumor potentially resulting in better outcomes.
Cancer of the colon and rectum is quite common. Any diagnosis of cancer can be alarming but it is important to know that there are good treatment options available. Screening tests, along with a few simple changes in your diet and lifestyle, can dramatically reduce your overall risk of developing colon cancer.
