Association between breast cancer and nipple suction as a sexual practice in Women from Northern Mexico

Infectious agents may play a role in breast cancer. Viral sequences of Epstein-Barr virus, human papillomavirus, and murine mammary tumor virus have been identified in breast tumors. A potential but unexplored pathway for viral entry is nipple suction during sexual practices. We aimed to evaluate the association between nipple suction as a sexual practice and breast cancer in women. We conducted a secondary analysis of a large population-based case-control study carried out between 2007 and 2011 in five northern Mexican states. The sample included 988 women with histologically confirmed incident breast cancer and 1019 matched controls without the disease. Information was obtained through standardized face-to-face interviews. Nipple suction was assessed via self-report, with responses categorized as never, sometimes, or frequently/always. We used logistic regression to estimate the association between breast cancer and nipple suction, adjusting for age and breastfeeding duration, with stratified analyses by menopausal status and tumor immunophenotype. Nipple suction was positively associated with breast cancer, with a significant dose-response trend (P < 0.001). Compared with never, women reporting occasional suction had higher odds [odds ratio (OR) = 1.38, 95% confidence interval (CI): 1.14-1.67], and those reporting frequent/always showed a markedly increased risk (OR = 14.36, 95% CI: 9.22-22.35). Associations were consistent across menopausal groups and tumor subtypes. Our findings raise the hypothesis that nipple suction could represent a potential route of exposure to oncogenic viruses present in saliva; however, molecular and virological studies are warranted to evaluate this possible mechanism.