Women who are either obese or very tall are more likely to die of ovarian cancer than their shorter, slimmer peers, according to a report in the journal Cancer Epidemiology Biomarkers & Prevention (Vol. 11, No. 9).

In this new study, researchers wanted to look at the relationship between obesity and height and ovarian cancer. They took information gathered from women who have participated in the ACS Cancer Prevention Study II.

According to the American Cancer Society (ACS) estimates for 2002, about 23,300 women will be diagnosed with ovarian cancer and 13,900 will die of this disease.

This large, ongoing prevention study has tracked the health of about 1.2 million men and women since 1982. When participants began this study, they answered questions about their personal and family history of cancer, their physical characteristics, and possible environmental and dietary exposures.

In looking at the risk of dying from ovarian cancer, Carmen Rodriguez, MD, senior epidemiologist, and her colleagues from the ACS, examined the information provided by the women who had died of ovarian cancer and compared them with the women who did not die from the disease. For this study, they excluded women who were pre-menopausal or had had a hysterectomy or oophorectomy (surgical removal of the ovaries).

The researchers found that the women who died of ovarian cancer were more likely to be obese. For example, a woman 5 feet 4 inches tall is considered overweight if she weighs between 143 to 173 pounds and obese if she weighs 174 pounds or more, Rodriguez said.

Obesity increased the risk of dying of ovarian cancer by 25% over women of normal weight.

They also found that very tall women were more likely to die of this cancer. Women who were 5 foot 9 inches and taller were 41% more likely to die of ovarian cancer than shorter women.

Rodriguez proposed two explanations of the results. The first is that obesity causes the ovarian cancer deaths because obese women make higher amounts of the female hormone, estrogen. Fat cells are an important source of estrogens in postmenopausal women.

In an earlier study, the ACS researchers had already shown women who take estrogens after menopause have a higher risk of dying of ovarian cancer. And, in a study reported in July in the Journal of the American Medical Association, researchers reported that there was an increased risk of cancer of the ovary in women who said they had used estrogens compared to women who never used any hormones.

The second explanation involves another hormone insulin-like growth factor. This hormone has been involved in other hormone-dependent cancers such as breast and prostate cancer. It is elevated in obese people. Because these growth factors are also responsible for height, this explanation accounts for both of the risk factors, height and obesity.

But Rodriguez cautioned that the relationship between obesity and height and ovarian cancer needs more scrutiny. Because this recent study used self-reported information on weight and height, this information may be inaccurate, she said.

Also, estrogens or insulin-like growth factor were not measured, so they don’t know if these are really the reasons for their results.

But the important message is one that has become more evident in the last few years: obesity may be a major cause of some cancers, particularly those that may be hormone dependent such as breast, uterus and now, ovarian, said Rodriguez.

"Results of this study emphasize once again the need for women to maintain a healthy weight throughout their life," she said.