Characteristics of breast cancer by molecular subtypes among a Hispanic Population

Breast cancer (BC) is the leading cause of cancer death among females in Puerto Rico (PR). It is a heterogeneous disease with distinct molecular subtypes based on gene expressions patterns. We aimed to assess the differences in breast cancer by molecular subtypes (BCMS) in PR. A case-case analysis was conducted using invasive BC cases consulted to the UPR-School of Medicine Immunoperoxidase Laboratory from 2008-2010. BCMS were characterized in 172 tumor specimens based on immunohistochemical surrogates for ER, PR and HER-2 status. The BCMS were defined as: luminal (ER+ and/or PR+), non-luminal (ER-, PR-). Logistic regression was used to evaluate risk factors differences between breast cancer cases by molecular subtypes. The luminal subtype was the most prevalent in our sample (75.0%) compared with the non-luminal (25.0%) subtype. Unadjusted association with BC risk factors differed by tumor subtypes. Compared to non-luminal subtype, luminal subtype cases are less likely to have older age at menopause (OR: 0.26, 95% CI: 0.08, 0.82), to be overweight or obese (OR: 0.89, 95% CI: 0.40, 1.94) and to have higher tumor histological grade (OR: 0.42, 95% CI: 0.18, 0.97). Even though this is a small pilot study, it is very suggestive of important risk factors differences for luminal breast cancer subtype. Future studies to further assess the association between BC risk factors and BCMS will add to the biologic understanding of BC.