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Endometrial Cancer Prevention (PDQ®): Prevention - Health Professional Information [NCI] - Overview

Note: Separate PDQ summaries on Endometrial Cancer Screening; Endometrial Cancer Treatment; and Uterine Sarcoma Treatment are also available.

Intervention Associated With Decreased Risk

Oral contraceptives

Based on solid evidence, at least 1 year's use of oral contraceptives containing estrogen and progesterone decreases endometrial cancer risk, proportionate to duration of use. This benefit lasts at least 15 years after cessation.[1,2]

Magnitude of Effect: Use of oral contraceptives for 4 years reduced risk by 56%, 8 years by 67%, and 12 years by 72%.

Study Design: Case-control studies and prospective studies.
Internal Validity: Good.
Consistency: Good.
External Validity: Good.

Harms

Based on solid evidence, current use of oral contraceptives is associated with an increased risk of blood clots, stroke, and myocardial infarction, especially among women who smoke cigarettes and who are older than 35 years.

Study Design: Randomized controlled clinical trials.
Internal Validity: Good.
Consistency: Good.
External Validity: Good.

Physical activity

Based on solid evidence, increased physical exercise is associated with a decreased risk of endometrial cancer.[3,4,5]

Magnitude of Effect: Regular exercise may be associated with a 38% to 46% decrease in risk, although a trend in risk reduction with increasing duration or intensity has not been shown.

Study Design: Multiple cohort and case-control studies.
Internal Validity: Good.
Consistency: Fair.
External Validity: Good.

Factors Associated With Decreased Risk

Increasing parity and lactation

Based on solid evidence, increased parity and duration of lactation are associated with a decreased risk of endometrial cancer.[6,7]

Magnitude of Effect: Parous women have a 35% decreased risk of endometrial cancer (hazard ratio = 0.65; 95% confidence interval [CI], 0.54–0.77) compared with nulliparous women. Duration of breastfeeding has also been associated with a decreased risk, with a 23% risk reduction noted with breastfeeding more than 18 months. The risk reduction was attenuated when adjusted for parity.[8,9]

Study Design: Prospective cohort study.
Internal Validity: Good.
Consistency: Good.
External Validity: Good.

Factors Associated With Increased Risk

Hormone therapy (HT)

Based on solid evidence, unopposed estrogen is associated with an increased risk of endometrial cancer.[10] This excess risk of endometrial cancer associated with postmenopausal unopposed estrogen therapy can be eliminated by adding progestin, but this is associated with an increased risk of breast cancer.[11,12]

Magnitude of Effect: The risk of endometrial cancer associated with unopposed estrogen use for 5 or more years is more than tenfold higher than nonhormone use. Addition of progesterone to estrogen negates this risk, but combined HT increases the risk of breast cancer, which is not observed with unopposed estrogen.

Study Design: Randomized controlled trials, cohort, and case-control studies.
Internal Validity: Good.
Consistency: Good.
External Validity: Good.

Harms

Based on solid evidence, the combined use of estrogen and progestin are associated with an increased risk of breast cancer, heart disease, stroke, and thrombosis.[11,13,14] Based on solid evidence, unopposed estrogen is associated with an excess risk of stroke and thrombosis.[15]

1|2

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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