Exercise May Cut Ovarian Cancer Risk
Benefit Reported With Moderate but Not Vigorous Physical Activity
Lower Risk Seen With Moderate Activity
Women who participated in the highest levels of moderate-intensity exercise had a decreased risk of ovarian cancer compared with women with lower levels of moderate intensity activity. Moderate levels of physical activity were defined as being equivalent to walking three to six times per week or golfing one or two times per week.
Decreased ovarian cancer risk was seen in women with high levels of moderate recreational physical activity before and after menopause, the study shows.
Overweight and obese women benefited a bit more than leaner women. Obesity, especially around the waistline, has been shown to increase ovarian cancer risk, and physical activity can reduce that fat. However, physical activity also lowered ovarian cancer risk for women with normal BMI, say the researchers, so other factors must come into play.
Women in Ontario also rated their activity at work. Ovarian cancer risk was also found to be lower in women with moderately active jobs.
Women with the highest levels of vigorous physical activity were not found to significantly reduce their risk of ovarian cancer.
How does physical activity help? No one is certain, but Pan outlines several possibilities.
Exercise might help the body's antioxidant and immune system defenses, combat obesity (especially around the waist), or affect hormones. Severe exercise could push the body too far, say researchers.
Reams of research have shown that activity rewards virtually the entire body, including the heart, bones, waistline, and brain.
The study has some limits. Self-reports can be flawed. Women may have mistakenly described their activity level "moderate" instead of "vigorous," say the researchers.
The questionnaires didn't cover the length of activity sessions, so there's no word on how long a woman would have to walk, for example, to get any ovarian cancer benefit.
About 20% of the patients the researchers wanted to include had already died, couldn't be located, or their physicians refused to contact them about the study. Of those who were contacted, nearly one in four (24%) did not return the questionnaire.
"This low response rate among cases was largely due to the poor prognosis of ovarian cancer, and it could affect the generalization of our results," write researchers.