The findings were presented at the ninth annual AACR Frontiers in Cancer Prevention Research Conference in Philadelphia this week.
The study examined hundreds of women and found that those who exercised at least 150 minutes weekly—which could be something as simple as moderate-paced walking—had a 34 percent reduced risk of endometrial cancer compared with their sedentary peers.
This association was particularly pronounced among active women with a body mass index (BMI) less than 25, where the reduction in risk was 73 percent compared with inactive women with a BMI greater than 25. Although body mass index showed a strong association with endometrial cancer, even women who were overweight, but still active, had a 52 percent lower risk.
While previous research has found a similar link between exercise and endometrial cancer risk, the Yale study examined physical activity measures in more detail and looked at joint associations of BMI and physical activity.
“These findings show the importance of physical activity in reducing risk of endometrial cancer,” said Hannah Arem, a doctoral student at School of Public Health and one of the paper’s authors. “Public health programs should encourage physical activity for those who have the highest risk of endometrial cancer, including women who are overweight and obese.”
Researchers examined data collected from a study that enrolled 668 women with endometrial cancer and compared them to 665 other women of similar age who served as controls.
They identified 29 types of activities (such as yoga, walking, tennis and swimming) and measured the intensity and frequency of the activity using a standardized scale.
The relationship between endometrial cancer risk and physical activity involves sex hormones and insulin pathways, with reductions in the percentage of body fat being a major biological factor.
Endometrial cancer forms in the tissue that lines the uterus. There are approximately 43,000 new cases of the disease in the United States each year and nearly 8,000 women die from the cancer annually.
Other School of Public Health researchers involved in the study include Melinda Irwin, Harvey Risch and Herbert Yu, also of the Yale Cancer Center, and Lingeng Lu and Yang Zhou.
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