Colon Cancer: Facts and Statistics that Might Surprise You
Colorectal cancer is the second most common malignancy in men and third in women, behind lung and breast cancer. In total, it accounts for about 15% of all cancers and will boast almost 150,000 new cases and claim 55,000 lives in 2011. Although substantial progress has been made in its treatment over the last 25 years, the 5-year survival rates have improved only modestly (about 65%) for advanced disease. Despite the publicity and initial awareness campaign that occurred following the death of Katie Couric’s husband (who died at the age of 42 from colorectal cancer) and her own televised experience undergoing colonoscopy, there is only modest knowledge and advocacy for colorectal cancer screening now, 13 years later.
It is believed that colorectal cancer is the result of genetic events that occur when environmental factors interact with an individual’s inherited or acquired susceptibility. Mutations occur at the cellular level in the colon lining and accumulate over time, causing normal tissue to evolve into colon polyps and ultimately into invasive disease.
Not all colon polyps become colon cancers. The risk of this malignant transformation depends on the size and type of the polyp, duration of its presence, and the number of polyps present. Based on studies of family histories, it is estimated that 20-30% of colorectal cancers have a significant hereditary component. There is a need to identify individuals who might benefit from early intervention by more vigilant screening or prevention with medicines or immunotherapy.
Although diet seems to play a role in the development of colorectal cancer, the food substances that contribute to colon cancer have been elusive. It has long been believed that diets high in animal fat, red meat, and total calories demonstrate an increase in incidence and mortality rates for colorectal cancer. Other factors causing elevated risk include use of alcohol and tobacco, sedentary lifestyle, and obesity. The mechanisms are unclear.
Early diagnosis of colorectal cancer, before any symptoms occur, could double the 5-year survival rate by finding it at an early stage when treatment is most effective. Presently, more than half of all colorectal cancers have spread to other areas of the body at the time of diagnosis, which means that many patients are already beyond the hope of cure by the time their cancer is found. This is an unfortunate statistic given the effectiveness of current screening methods and improved surgical techniques, radiotherapy and combination chemotherapy or immunotherapy.
There is little doubt that a screening colonoscopy (a 6 foot lighted flexible fiber optic tube attached to a video camera passed into the rectum to visualize the colon lining) is effective in identifying silent polyps and colon cancers. Use of other tests such as fecal occult blood tests, sigmoidoscopy, and barium enema, are helpful in leading to further evaluation. Tests for identification of abnormal DNA mutations in stool is investigational at this point. Colonoscopy remains the gold standard and has the added advantage of being both diagnostic and therapeutic in being able to remove polyps at the time of the procedure or biopsy an abnormal area in question.
What is the greatest risk factor for colorectal cancer? Age is the single most determinant force. The risk increases above the age of 40 and continues to rise sharply between 50-55, peaking around 75. Colorectal cancers below the age of 40 can occur in those with strong family risk factors.
How does colon cancer present? What are the symptoms? The most common sign is rectal bleeding, and the most common symptoms include a change in bowel habits, straining at stool, a change in stool caliber, or increasing gaseousness. Unfortunately, many of these are seen in the later stages of the disease. Cancer of the right colon is usually asymptomatic until large. Other presentations may include unexplained anemia, fatigue or weight loss. If you experience any of these symptoms, be sure to see your physician.
What is the best way to screen for colorectal cancer and colon polyps? Be sure you undergo a digital rectal examination and fecal occult blood test on a routine physical exam over the age of 40, or earlier if you know of colorectal cancer or colon polyps in close relatives. Colonoscopy is an integral part of the evaluation, beginning at age 50 (45 for African Americans) with no symptoms, or at age 40 for those with family histories, but performed anytime if any “flag symptoms” described above are present.
How is colonoscopy performed? The prep to clear out the colon for optimal visualization is taken the day before and, while considered unpleasant, it is relatively simple. The procedure itself is carried out in an outpatient endoscopic facility under sedation. The entire experience accounts for several hours, although the procedure time itself is usually less than a half hour.
Successful primary prevention of colorectal cancer depends on public education and counseling, more aggressive screening in individuals at risk, but more importantly (given the majority of colorectal cancers occur in patients without family history), general screening by colonoscopy beginning at 50 years of age.
Don’t be left out. To paraphrase Smokey the Bear, only YOU can prevent colorectal cancer.
For more information about colon cancer and prevention, visit our website at www.capitaldigestivecare.com or request a free information kit at firstname.lastname@example.org or (240) 485-5207. Capital Digestive Care has 16 offices conveniently located throughout the Washington Metropolitan Area, including, Montgomery, Howard, Prince George’s, and Frederick counties.
Additional posts by Mark Birns, MD, FACP, FACG, AGAF
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