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Endometrial Cancer Prevention (PDQ®): Prevention - Health Professional Information [NCI] - Description of Evidence

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A Swedish population-based case-control study confirms these findings. Women who used any type of oral contraceptive had a 30% risk reduction (odds ratio [OR] = 0.7; 95% CI, 0.5–0.9) and women who used progestin-only pills had a 60% risk reduction (OR = 0.4; 95% CI, 0.2–1.4). Women who used COCs for at least 3 years had a 50% risk reduction (OR = 0.5; 95% CI, 0.3–0.7) and those who used COCs for at least 10 years had an 80% risk reduction (OR = 0.2; 95% CI, 0.1–0.4). Overall, risk decreased by 10% per year of COC use and was observed for atypical hyperplasias as well as all grades of invasive tumors.[13]

Physical activity

Several cohort [14,15] and case-control [16,17,18,19,20,21,22,23,24] studies of physical activity and endometrial cancer reveal a weak to moderate inverse relationship, despite varying methods of assessing physical activity levels. For postmenopausal women enrolled in The Netherlands Cohort Study on Diet and Cancer, a 46% reduction (RR = 0.54; 95% CI, 0.34–0.85; P = .002) in risk of endometrial cancer was reported in those women who were physically active 90 minutes or more per day compared with less than 30 minutes each day.[25] One case-control study of 822 endometrial cancer cases and 1,111 population controls showed that regular exercise was associated with a 38% decrease in risk (OR = 0.62; 95% CI, 0.51–0.76) without a trend for increasing duration or intensity of physical activity.[26] The Breast Cancer Detection Project Follow-up Study, using a prospective cohort, did not confirm an association between recent physical activity levels and risk.[27] It is unknown whether physical activity reduces endometrial cancer risk by reducing obesity, by reducing serum estrone levels, or by another mechanism.[28]

Factors Associated With Decreased Risk

Increasing parity and lactation

Decreased risk of endometrial cancer is associated with parity and lactation, perhaps by inhibiting ovulation. A case-control study conducted in Mexico City, among low-risk women, indicates a 58% to 72% reduction in risk of endometrial cancer associated with increasing duration of lactation. A significant trend was seen for duration of lactation and for the number of children breastfed.[29] A population-based case-control study, comparing Wisconsin women who breastfed for at least 2 weeks versus those who did not, was negative (OR = 0.90; 95% CI, 0.72–1.13). Increasing duration of lactation was not associated with a decrease in disease risk, but breastfeeding within the past three decades was associated with reduced risk (OR = 0.58; 95% CI, 0.36–0.96), as was the first breastfeeding after age 30 years (95% CI, 0.28–0.90).[30] The European Prospective Investigation into Cancer and Nutrition observed a decreased risk associated with parity compared with nulliparous women (hazard ratio = 0.65; 95% CI, 0.54–0.77) with a trend of decreasing risk with increasing number of full-term pregnancies (P < .0001). While breastfeeding for more than 18 months was associated with a decreased risk, the association attenuated and was no longer statistically significant after adjusting for the numbers of full-term pregnancies.[31]

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WebMD Public Information from the National Cancer Institute

Last Updated: February 25, 2014
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.
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