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

Note: Separate PDQ summaries on Ovarian Cancer Screening and Ovarian Epithelial Cancer Treatment are also available.

Factors With Adequate Evidence of Increased Risk of Ovarian Cancer

Hormone replacement therapy

Based on fair evidence, current or recent hormone therapy is associated with a small increased risk of ovarian cancer. Risks attenuate after hormone therapy is discontinued. Risk may be stronger with estrogen-only therapy compared with combined estrogen-progestin therapy.

Magnitude of Effect: Modest with observed relative risks (RRs) of 1.20 to 1.8.

Study Design: One randomized clinical trial, cohort and case-control studies.
Internal Validity: Good.
Consistency: Fair.
External Validity: Good.

Perineal talc exposure

Based on solid evidence, perineal application of talc is associated with a small increased risk of ovarian cancer. The International Agency for Research on Cancer has concluded that perineal talc is a possible carcinogen.[1]

Magnitude of Effect: Odds ratio of 1.24 (95% confidence interval [CI], 1.15-1.33).

Study Design: Cohort and case-control studies.
Internal Validity: Good.
Consistency: Good.
External Validity: Good.

Obesity, weight gain and height

Based on fair evidence, obesity, weight gain, and height are associated with a modest increased risk of ovarian cancer.

Magnitude of Effect: Based on an overview analysis of 25,157 women with ovarian cancer and 81,211 women without ovarian cancer from 47 epidemiological studies, the RR of ovarian cancer per 5 cm increase in height is 1.07 (95% CI, 1.05–1.09). The RR of ovarian cancer per 5 kg/m2 increase in body mass index is 1.10 (95% CI, 1.07–1.13) among never-users of hormone therapy and 0.95 (95% CI, 0.92–0.99) among ever-users of hormone therapy.

Study Design: Cohort and case-control studies.
Internal Validity: Good.
Consistency: Good.
External Validity: Good.

Factors With Adequate Evidence for a Decreased Risk of Ovarian Cancer

Oral contraceptives

Benefits

Based on solid evidence, oral contraceptive use is associated with a decreased risk of developing ovarian cancer.

Magnitude of Effect: The degree of risk reduction varies by duration of oral contraceptive use and time since last use. For 1 to 4 years of oral contraceptive use the RR reduction is 22%, and for 15 or more years of use the RR reduction is 56%. The reduction in risk persisted for over 30 years after use was discontinued but the degree of reduction attenuates over time. The risk reduction per 5 years of use was 29% for women who discontinued use less than 10 years ago and decreased to 15% for women who discontinued use 20 to 29 years ago. Ten years of use reduced cancer incidence before age 75 years from 1.2 to 0.8 per 100 users and mortality from 0.7 to 0.5 per 100 users. The number needed to treat for 5 years was estimated to be about 185 women.

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