Sedentary women may have increased ovarian cancer risk

[unseennude]

High levels of sedentary behavior, such as reading or watching television, seem to be associated with a higher incidence of ovarian cancer, results of a prospective study suggest. However, the same study failed to identify any impact of light and moderate physical activity on developing the disease.

The numerous studies that assessed the link between physical activity and ovarian cancer yielded findings ranging from a negative association to no association to a positive association, note Dr. Alpa V. Patel and colleagues at the American Cancer Society in Atlanta. Only one study, conducted in China, examined the role of sedentary activity, which was associated with an increased ovarian cancer risk that did not reach statistical significance.

Dr. Patel's group evaluated data from the American Cancer Society Cancer Prevention Study II Nutrition Cohort, which prospectively followed nearly 60,000 postmenopausal women from 1992 until 2001. During that time, 314 incident cases of ovarian cancer were documented, the researchers report in the April 15th issue of the American Journal of Epidemiology.

The subjects had completed questionnaires every 2 years asking about time spent in recreational and nonrecreational physical activities. The women were also questioned about the average number of hours per day spent sitting (apart from time at work).

As noted, the authors observed no statistically significant relationships between type or degree of physical activity and ovarian cancer incidence.

However, women who spent more than 3 hours per day sitting during leisure time had a 55% higher risk of developing ovarian cancer than did women who were less sedentary (p for trend = 0.01). The relationship remained significant after adjusting for BMI, demographics, family and reproductive history, and the use of hormone replacement therapy.

According to the authors, the association could be mediated by findings in other studies that "sedentary behavior has been associated with obesity and with metabolic abnormalities, resulting in increased circulating estrogen, insulin, and other hormones that may promote cell proliferation."

They call for further research in this area "with a focus in observational studies on better understanding the etiologic role of endogenous hormones in ovarian carcinogenesis