Assessing the Role of Pesticide Exposure and Menopausal Status in Breast Cancer Prognosis Among Rural Women.

[INTRODUCTION] Pesticides are recognized endocrine disruptors that may influence breast cancer risk and progression, yet their impact on disease characteristics according to menopausal status remains unclear, particularly in rural populations with high exposure levels. This study aimed to evaluate the impact of pesticide exposure on the clinicopathological profile of breast cancer among rural women, with a focus on differences between premenopausal and menopausal patients.

[METHODS] A cohort of 189 women diagnosed with invasive breast cancer at a cancer hospital in southwestern Paraná State, Brazil, was retrospectively analyzed. Pesticide exposure was determined through a validated questionnaire, classifying women as exposed or unexposed. Menopausal status was recorded from medical charts and categorized as premenopausal or menopausal. Clinicopathological features were compared across groups.

[RESULTS] Pesticide-exposed premenopausal patients presented more cases of low histological grade tumors than unexposed women did (46.28% vs 23.14%, respectively,  = .0081). Additionally, more exposed patients had angiolymphatic emboli (15.22% to unexposed and 47.83% to exposed,  = .0170). Patients exposed at menopause had more tumors without estrogen receptor expression (13.16% unexposed and 28.95% exposed,  = .022) and a lower ki67 index (23.08%) than unexposed patients (6.15%,  = .0055), with a prevalence of tumors larger than 2 cm (11.82% unexposed and 21.82% exposed,  = .0481). A multivariable regression analysis was performed and showed both age (β = 0.03698, 95% CI: -1.013 to 1.108) and BMI (β = 0.1293, 95% CI: -0.5552 to 0.8120) had no significant effects. Conclusion: These findings suggest that chronic pesticide exposure during critical windows of breast development may alter disease presentation according to menopausal status. Given the high pesticide burden in a rural cohort, it is important to consider environmental exposures in breast cancer prognosis, especially among vulnerable populations.