Obesity Worsens Colon Cancer in Women

Obese Women Fare Worse After Colon Cancer Diagnosis

WebMD Health News

June 30, 2003 -- Obesity not only increases the risk of developing colon cancer, but for women it may also make the disease more dangerous and deadly. New research shows obese women with colon cancer are more likely to die from their disease.

The study, published in the journal Cancer, showed that women with a body mass index (BMI, a measure of weight in relation to height, used to indicate obesity) of more than 30 were 34% more likely to die from their colon cancer than normal-weight women.

But obesity doesn't seem to have the same effect on men's colon cancer. Researchers found men's BMI did not significantly influence survival or cancer recurrence.

Although obesity is a known risk factor for colon cancer, researchers say less is known about the effect of weight on treatment or overall outcomes of people with colon cancer. In the study, researchers followed some 3,800 men and women with advanced (stage II or III) colon cancer.

Among women, researchers found the risk of death due to colon cancer rose as BMI levels increased.

On the positive side, the study also found that obese women had lower rates of chemotherapy-related complications or side effects, such as nausea or vomiting, than normal weight women. Researchers say this is important because it shows that obese women can tolerate chemotherapy at least as well as nonobese patients, even when they are given higher doses because of more body weight.

Although some have suggested that the higher death rates among obese women might reflect the fact that chemotherapy doses are sometimes calculated according to ideal weight rather than actual weight among obese women, the study showed that obese women still fared worse even after adjusting for possible underdosing.

Instead, researcher Jeffrey Meyerhardt, MD, MPH, of the Dana-Farber Cancer Institute, and colleagues say several other factors might explain the gender disparity in the risks faced by obese women with colon cancer.

For example, obese women have higher levels of estrogen circulating in the body, are more likely to be insulin resistant (a precursor to diabetes), and have higher rates of diabetes. All of these factors are thought to promote the growth of cancerous tumors.

Researchers say more studies are needed to confirm this influence of obesity on colon cancer risk, as well as examine the effect of weight loss, physical activity, and diet on the long-term outcome of people with advanced colon cancers.

SOURCE: Cancer, August 1, 2003.