A case-control analysis of oral contraceptive use and breast cancer subtypes in the African American Breast Cancer Epidemiology and Risk Consortium

Hormone-related risk factors for breast cancer in women under age 50 years by estrogen and progesterone receptor status: results from a case-control and a case-case comparison

Ma H et al., 2006·Breast Cancer Res

It has been suggested that hormonal risk factors act predominantly on estrogen receptor and progesterone receptor (ER/PR)-positive breast cancers. However, the data have been inconsistent, especially in younger women. We evaluated the impact of age at menarche, pregnancy history, duration of breastfeeding, body mass index, combined oral contraceptive use, and alcohol consumption on breast cancer risk by ER/PR status in 1,725 population-based case patients and 440 control subjects aged 20 to 49 years identified within neighborhoods of case patients. We used multivariable unconditional logistic regression methods to conduct case-control comparisons overall as well as by

Hormonal contraception and risk of breast cancer and breast cancer in situ among Swedish women 15-34 years of age: A nationwide register-based study

Niemeyer Hultstrand J et al., 2022·Lancet Reg Health Eur

Evidence on a possible association between newer hormonal contraceptives (HC) and risk of breast cancer remains inconclusive, especially as concerns progestogen-only methods. In this nationwide prospective cohort study, all Swedish women aged 15-34 at study start on January 1(st) 2005, or who turned 15 years during the study period, were followed until December 31(st) 2017. Using information from seven National Registers, we assessed the risk ratio of developing breast cancer and breast cancer in situ in relation to different HC using Poisson regression. We adjusted the analyses for several known confounders of breast cancer. This cohort included 1.5 million women providing more than 14 million person-years. During the study period, 3842 women were diagnosed with breast cancer. Compared with never users of any HC, we found no increased risk of developing breast cancer among current users of any combined HC, IRR 1.03 (0.91-1.16), whereas current users of progestogen-only methods had an increased risk of developing breast cancer, IRR 1.32 (1.20-1.45). Across all types of HC, the risk of developing breast cancer appeared to be highest the first five years of use (combined HC IRR 1.39 (1.14-1.69); progestogen-only methods IRR 1.74 (1.44-2.10). The risk disappeared ten years after the women stopped using HC. The absolute risk of breast cancer per 100,000 women-years was 22.4 for never users, 10.9 for current users of combined HC, and 29.8 for current users of progestogen-only methods. Current use of progestogen-only methods is associated with a small increased risk of developing breast cancer, whereas we could only detect an increased risk among users of combined HC during the first five years of use. This may partly be explained by a selective prescription of progestogen-only methods to women with risk factors for breast cancer, like smoking or obesity. As the absolute risk of breast cancer was small, the many health benefits associated with HC must also be taken into account in contraceptive counselling. This study was funded by the Swedish Cancer Society and by the Uppsala County Council, the Faculty of Medicine at Uppsala University.

Oral contraceptives and breast cancer risk overall and by molecular subtype among young women

Beaber EF et al., 2014·Cancer Epidemiol Biomarkers Prev

Evidence suggests that recent oral contraceptive (OC) use is associated with a small increased breast cancer risk; yet risks associated with contemporary OC preparations and by molecular subtype are not well characterized. We conducted a population-based case-control study of invasive breast cancer among women ages 20 to 44 residing in the Seattle-Puget Sound area from 2004 to 2010 (985 cases and 882 controls). We collected information on contraceptive use and participant characteristics via an in-person interview. Multivariable-adjusted logistic regression was used to calculate odds ratios (OR) and 95% confidence intervals (CI). Lifetime duration of OC use for ≥ 15 years was associated with an increased breast cancer risk (OR, 1.5; 95% CI, 1.1-2.2). Current OC use (within 1 year of reference date) for ≥ 5 years was associated with an increased risk (OR, 1.6; 95% CI, 1.1-2.5) and there were no statistically significant differences in risk by OC preparation. Risk magnitudes were generally greater among women ages 20 to 39, and for estrogen receptor-negative (ER(-)) and triple-negative breast cancer (current use for ≥ 5 years among ages 20-39: ER(-) OR, 3.5; 95% CI, 1.3-9.0; triple-negative OR, 3.7; 95% CI, 1.2-11.8), although differences between groups were not statistically significant. Long-term use of contemporary OCs and current use for ≥ 5 years was associated with an increased breast cancer risk among women ages 20 to 44. Risk may be greater among younger women and for ER(-) and triple-negative breast cancer, but these findings require confirmation. Continued surveillance and pooled analyses of OC use and breast cancer risk by molecular subtype are needed as OC preparations evolve.

The intrauterine device. Contraceptive or abortifacient?

Parchment M et al., 2026·Minn Med