Colorectal Cancer
The American Cancer Society estimates that there will be over 140,000 new cases of colorectal cancer this year, and close to 50,000 deaths. The lifetime risk of developing colorectal cancer is one out of every twenty Americans.

Colorectal cancer is the result of uncontrolled malignant growth of the glands that line the inside of the colon and rectum (cancer of the anus is a separate entity). Most colorectal cancers take years to develop, beginning with small growths called polyps or adenomas. These are benign, but can progress over time to become malignant cancers.

Risk for developing colorectal cancer increases with age, with most cases occurring in the 60’s and 70’s, but earlier development is possible. Other risk factors include race (African-American, Eastern European descent), cancer history (family or personal history of colorectal cancer, personal history of breast, uterine, ovarian cancer), inflammatory bowel disease (Crohn’s disease, ulcerative colitis), and smoking.

Diets high in fat, red meat and processed meats and low in fiber is the largest modifiable risk factor for developing colorectal cancer. Alcohol intake has been implicated as a risk factor as well, although there is some debate on to what extent. There are also genetic causes for colorectal cancer (familial adenomatous polyposis (FAP), hereditary nonpolyposis colorectal cancer (HNPCC, Lynch syndrome), Gardner syndrome) that dramatically increase the risk of developing colorectal cancer, often before age 50.

In the absence of colonoscopy, symptoms of colorectal cancer may be non-existent until advanced. The most frequently cited first symptom is blood in the stool, followed by abdominal pain and tenderness, a change in bowel habits such as diarrhea and constipation, unintended weight loss, and narrow stools (indicates a narrowing of the rectum from a tumor).

Diagnosis of colorectal cancer will be started with a physical exam (tumors may be felt in the rectum or abdomen) blood tests (complete blood count, liver function tests) and testing for blood in the stool, but formal diagnosis is made by colonoscopy (camera inserted into the colon) and biopsy. After diagnosis is made, the stage of the cancer is determined by CT, MRI, and PET scan. Early stage colorectal cancer has an excellent survival rate, but as it progresses to the lymph nodes and other organs, survival drops precipitously.

Treatment for colorectal cancer almost always requires surgical removal of the affected part of the colon, which may be partial or complete. In early stage cancers, this may be sufficient. Once it advances, chemotherapy becomes a necessary addition. Frequently used therapies include irinotecan, oxaliplatin, capecitabine, and 5-fluorouracil, as well as monoclonal antibodies such as cetuximab (Erbitux), panitumumab (Vectibix), and bevacizumab (Avastin)

Remember that almost all colorectal cancers are highly survivable and in some cases completely cured if they are detected early. For this reason, colonoscopy is recommended for every adult when they reach age 50, and after age 40 if there are risk factors like previous cancer, family history, or inflammatory bowel disease.