Colon and Rectal Cancer Prevention
Colon cancer is the second leading cause of cancer-related deaths in the United States. Leaving skin cancers aside, colon cancer is the third most common cancer diagnosed in the United States. In 2005 colon cancer is expected to cause over 56,000 deaths. Contrary to what most people believe, prevention of colon cancer is possible.
Is Colon Cancer Preventable?
Recent research has shown that an encouraging number of colon cancers can be prevented. Below is a summary of the measures you can take to prevent colon cancer.
A Diet To Prevent Colon Cancer
Diet can both increase and decrease your risk of cancer, depending on what you eat. So far, the closest associations were found for red meat, fruits and vegetables.
Avoiding Red Meat Reduces the Risk of Colon Cancer
There are quite a few studies linking red meat consumption to colon cancer. One of the most recent and revealing ones was published in the beginning of 2005 in the Journal of the American Medical Association. Entitled "Meat Consumption and Risk of Colorectal Cancer
", the study followed almost 150,000 adults between the ages of 50 and 74 over the course of about 20 years.Over the 20 years period, the participants filled out food questionnaires several times. At the end of the study, researchers compared the diets of those who developed colon cancer to those who didn't. The findings? You guessed: those who ate the most red meat had a 30%-40% higher chance of developing colon cancer than those who ate the least. In addition, participants who ate the most processed meats had a 50% higher chance of developing colon cancer compared to those who ate the least.
To read more about this study, please go to the American Cancer Society page dedicated to colon cancer and meat consumption
How does read meat increase the risk of colon cancer? We don't know all the details yet, but it seems red and processed meats increase the risk of colon cancer by generating chemicals that induce the cancerous transformation of cells in the colon. Some of these chemicals are heterocyclic amines and nitrates.
Fruit, Vegetables, Dietary Fiber, and Risk of Colorectal Cancer
For a long time, it was thought that dietary fiber was the main protector factor against colon cancer found in fruits and vegetables. Recent studies indicate fiber may not be so important in colon cancer prevention
Fruits and vegetables are beneficial in the prevention of numerous cancers, including colorectal cancer. It is not completely understood what exactly provides this protection. Some experts think in case of colon cancer it is the folate found in generous amounts in green, leafy vegetables, that is responsible for the protection. Indeed, folate has been proved to protect against colorectal cancer. In one of the best known studies, the Nurses' Health Study, researchers found that women who reported the highest intake of folate, for at least 15 years, had a 75 percent reduced risk of colon cancer
. An interesting note from the leaders of the study was that, even though multivitamin supplements containing folate appeared to work, the thought people would do better if they ate fruits and vegetables rather than just take a supplement.
Another study, entitled Fruit, Vegetables, Dietary Fiber, and Risk of Colorectal Cancer
, published in the April 4, 2001 issue of the Journal of the National Cancer Institute produced similar results. A number of 61,463 Swedish women were followed for a total of 9.6 years, and data regarding their food habits was collected. During this time, a total of 460 women developed colorectal cancer. Looking at the entire group of participating women, researchers found that total fruit and vegetable consumption was inversely associated with colorectal cancer risk. Specifically, those who consumed less than 1.5 servings of fruit and vegetables per day had a 65 percent higher incidence of colon cancer compared with those who consumed more than 2.5 servings.
Alcohol and Risk of Colorectal Cancer
In the Nurses' Health Study, drinking alcohol was found to increase the risk of colon cancer
by over 80%. This finding was confirmed by a pooled analysis of 8 studies published in the April 2004 issue of the Annals of Internal Medicine: people who reported drinking more than 30 grams of alcohol per day (the equivalent of 2 average-size drinks) experienced an increase in risk for colorectal cancer
This is just another example of how alcohol can harm one's health.
Exercise, Body Weight and Risk of Colorectal Cancer
A number of studies have indicated regular exercise has a protective effect against colorectal cancer. One of the best known is a Harvard University study on 47,723 male health professionals who were followed for 6 years. Regular exercise was associated with a 50 percent decrease in the incidence of colon cancer
Another very interesting study measured the levels of bowel prostaglandins in people who exercised. Prostaglandins are important chemicals found in various sites in the body, playing key roles in inflammatory processes. Bowel prostaglandins, when present in excess, are believed to stimulate the formation of polyps that subsequently become cancerous. A 30 mintes jog or a one hour walk daily was enough to decrease the prostaglandin levels by 28 percent
In addition to decreasing the levels of harmful prostaglandins, exercise lowers the risk of colon cancer by at least another mechanism. It simply helps to keep things moving along the intestinal track. This increase in the transit time allows less time of contact between the carcinogenic chemicals in the stool and the walls of the colon.
Another likely protective mechanism involves exercise's effect on insulin levels. Insulin stimulates the growth of various cells, including cancerous cells. People who exercise regularly have lower insulin levels, lower body weight and lower incidence of colon cancer.
Aspirin Can Prevent Colon Cancer
As pointed out earlier, intestinal prostaglandins tend to increase the risk of colon cancer. As aspirin inhibits prostaglandin synthesis, researchers examined it's potential benefit for colon cancer prevention. Indeed, regular use of aspirin - i.e. taking more than two tablets a week, up to a maximum of 14 tablets a week - reduced the risks of colonic polyps by 25 percent
. The actual mechanism by which aspirin inhibits colon cancer is more complex than prostaglandin inhibition,and this is a very active area of research right now.
The big downside of aspirin is it's tendency to increase the risk of gastro-intestinal bleeding. I personally think a healthy lifestyle is the best choice when it comes to colon cancer prevention - or any type of chronic disease prevention, for that matter.
Smoking Tobacco Increases the Risk of Colon Cancer
The Cancer Prevention Study II conducted by the American Cancer Society provided enough information for the researchers to claim that about 12 percent of colon cancers are directly linked to smoking
The good news is that if you quit smoking, the risk decreases.
Other Protective Factors for Colon Cancer
Recent research indicates calcium and vitamin D may play important protective roles. It is also likely other phytochemicals from plant foods may have similar roles. Stay tuned - we will update this page as soon as new studies reveal other protective factors.
Recently there has been a lot of interest in the potential cancer protecting benefit of statins, which are drugs used to lower elevated cholesterol levels. Upon closer look, statins were found to have a neutral effect on cancer and cancer death risk. In a recent article published in the The Journal of the American Medical Association, entitled Statins and Cancer Risk
, researchers concluded: "We found that no type of cancer was affected by statin use and no subtype of statin affected the risk of cancer".
Finally, we are currently working on an interactive questionnaire designed to evaluate your lifestyle from the perspective of colon cancer risk. Come back soon to find out what you need to do to lower your risk of colon cancer!