Risk factors for the development of endometrial lesions in breast cancer patients using tamoxyphen: a retrospective cohort study

breast cancer is the cancer with the highest incidence in women in Brazil, representing 29.7% of all cancers. More than two thirds of women with breast cancer show expression for hormone receptors, and in these cases, hormone therapy with tamoxifen is indicated, which may represent a risk factor for the development of endometrial cancer (four-fold greater relative risk). this study aimed to evaluate the association of tamoxifen and the development of endometrial disturbances and to assess possible other associated risk factors. a total of 364 breast cancer patients were evaluated, 286 who used tamoxifen and 78 who did not use this hormone therapy. Results: patients who used tamoxifen had a mean follow-up time of 51.42 months similar to those without hormone therapy (p=0.081). A total of 21 (7.3%) women who used tamofixen and no cases among women without hormone therapy presented endometrial changes during follow-up (p=0.01). Despite information regarding obesity was available for only 270 women, obesity was also significantly associated with the development of endometrial changes (p=0.008). furthermore, the association between tamofixen and endometrial changes remained significant (p=0.039) after adjusting for obesity.