Reproductive factors and risk of breast cancer by tumor subtypes among Ghanaian women: A population-based case–control study

Show simple item record Clegg-Lamptey, J-N. Figueroa, J.D. Lynn, B.C.D. Edusei, L. Titiloye, N. Adjei, E. Yarney, J. Wiafe-Addai, B. Awuah, B. Duggan, M.A. Wiafe, S. Nyarko, K. Aitpillah, F. Ansong, D. Hewitt, S.M. Ahearn, T. Garcia-Closas, M. Brinton, L.A. Ghana Breast Health Study Team 2020-06-29T12:38:22Z 2020-06-29T12:38:22Z 2020-02-18
dc.description Research Article en_US
dc.description.abstract Higher proportions of early-onset and estrogen receptor (ER) negative cancers are observed in women of African ancestry than in women of European ancestry. Differences in risk factor distributions and associations by age at diagnosis and ER status may explain this disparity. We analyzed data from 1,126 cases (aged 18–74 years) with invasive breast cancer and 2,106 controls recruited from a population-based case–control study in Ghana. Odds ratios (OR) and 95% confidence intervals (CI) were estimated for menstrual and reproductive factors using polytomous logistic regression models adjusted for potential confounders. Among controls, medians for age at menarche, parity, age at first birth, and breastfeeding/pregnancy were 15 years, 4 births, 20 years and 18 months, respectively. For women ≥50 years, parity and extended breastfeeding were associated with decreased risks: >5 births vs. nulliparous, OR 0.40 (95% CI 0.20–0.83) and 0.71 (95% CI 0.51–0.98) for ≥19 vs. <13 breastfeeding months/pregnancy, which did not differ by ER. In contrast, for earlier onset cases (<50 years) parity was associated with increased risk for ER-negative tumors (p-heterogeneity by ER = 0.02), which was offset by extended breastfeeding. Similar associations were observed by intrinsic-like subtypes. Less consistent relationships were observed with ages at menarche and first birth. Reproductive risk factor distributions are different from European populations but exhibited etiologic heterogeneity by age at diagnosis and ER status similar to other populations. Differences in reproductive patterns and subtype heterogeneity are consistent with racial disparities in subtype distributions. en_US
dc.language.iso en en_US
dc.publisher International Journal of Cancer en_US
dc.relation.ispartofseries 2020;
dc.subject reproductive risk factors en_US
dc.subject subtype heterogeneity en_US
dc.subject racial disparities en_US
dc.subject breast cancer en_US
dc.title Reproductive factors and risk of breast cancer by tumor subtypes among Ghanaian women: A population-based case–control study en_US
dc.type Article en_US

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