Figure 2.

Risk factors and differential associations with the risk of estrogen receptor (ER)–positive and ER-negative tumor subtypes based on case–control comparisons in 12 population-based studies. Case–control comparisons were stratified by mutually exclusive categories of ER status. The analysis included 14 795 case patients (10 900 for ER⁺ and 3895 for ER⁻) and 17 399 control subjects pooled across 12 studies. The black diamonds and the horizontal lines represent odds ratios (ORs) and corresponding 95% confidence intervals (CIs), respectively. Odds ratios were obtained from unconditional logistic regression models with case–control status (case patients were stratified by ER status) as outcome variables and age, study, and each risk factor separately as independent variables. The associations between body mass index (BMI) in women older than 50 years and family history in first-degree relatives are not shown because they were not statistically significantly modified by ER status in case–case comparisons.Ref = referent category. Odds ratio are presented on the log scale.