Table 25Strength of evidence domains for the effect of OC use on breast cancer

ComparisonNumber of Studies (Women and/or Person-years)Domains Pertaining to SOESOE and Magnitude of Effect (95% CI)
Risk of BiasConsistencyDirectnessPrecision
Incidence of Breast Cancer in Overall Population
Ever vs. never use23 (356,023 across 20 studies and 3,981,072 person-years across 3 studies)MediumConsistentDirectPreciseModerate
1.08 (1.00 to 1.17)
Duration of use14 (291,407 across 12 studies and 2,898,072 person-years across 2 studies)MediumInconsistentDirectImpreciseLow
No increase in risk for longer durations of use
Time since last use11 (200,258)HighInconsistentDirectImpreciseLow
Reduced risk over time since last use
0–5 yr: 1.21 (1.04 to 1.41)
5–10 yr: 1.17 (0.98 to 1.38)
10–20 yr: 1.13 (0.97 to 1.31)
>20 yr: 1.02 (0.88 to 1.18)
Incidence in BRCA1- or BRCA2-Positive Women
Ever vs. never use5 (4555 across 4 studies, and 65,180 person-years in 1 study)MediumInconsistentDirectImpreciseLow
Trend toward slight increase in risk
1.21 (0.93 to 1.58)
Incidence in Women With Family History
Ever vs. never use3 (9280)HighInconsistentDirectImpreciseInsufficient
Not performed
Incidence in Young Women
Ever vs. never use3 (5716)MediumInconsistentDirectImpreciseInsufficient
Not performed
Mortality From Breast Cancer
Ever vs. never use3 (54,606 across 2 studies and 602,700 person-years in 1 study)MediumConsistentDirectImpreciseLow
No significant increase in risk
0.94
(0.87 to 1.02)
Survival After Diagnosis of Breast Cancer
Ever vs. never use3 (9606)MediumConsistentDirectImpreciseLow
No significant increase in risk

BRCA = breast cancer genetic mutation; CI = confidence interval; SOE = strength of evidence; yr = year/years

From: 3, Oral Contraceptives and Other Cancers

Cover of Oral Contraceptive Use for the Primary Prevention of Ovarian Cancer
Oral Contraceptive Use for the Primary Prevention of Ovarian Cancer.
Evidence Reports/Technology Assessments, No. 212.
Havrilesky LJ, Gierisch JM, Moorman PG, et al.

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