Breast cancer patients have increased risk of developing mTOR inhibitor-associated stomatitis.

A total of 115 patients who used everolimus were evaluated. The mean age was 57 (±13.3) years old, and 87 patients were women (75.6%). mTOR inhibitor-associated stomatitis (mIAS) was observed in 36 patients (31.3%). The lesions ranged from 0.5 cm to 1.5 cm, and the tongue was the main site affected. In addition, 21 patients (58.3%) required a dose reduction of everolimus due to mIAS. Patients who had breast cancer presented 2.29-fold higher risk for developing mIAS when compared to patients with kidney or neuroendocrine tumors. This study emphasizes the high prevalence of mIAS in patients using everolimus, in particular, in patients with breast cancer.