Predictive factors for the response to neoadjuvant treatment in patients with stage II and III breast cancer.

This study aimed to identify predictive factors for response to neoadjuvant treatment in patients with stage II and III breast cancer. A cross-sectional study evaluated the medical records of 440 patients treated in the Oncology Department of a University Hospital in Brazil between 2007 and 2022. Response to neoadjuvant treatment was classified into three groups: pathological complete response (pCR), partial response, and no response. Predictive factors were analyzed using multinomial regression. Most patients showed partial response (73.9%). Patients aged 39 years or younger were three times more likely to achieve pCR [relative risk (RR) = 3.04, 95% confidence interval (CI): 1.51-6.15]. Conversely, patients with luminal A and B subtypes had a lower likelihood of pCR (RR = 0.09, 95% CI: 0.04-0.18). The presence of diabetes (RR = 7.18, 95% CI: 2.43-21.1) and stage IIIB and IIIC (RR = 7.41, 95% CI: 1.48-37.0) increased the risk of no response by at least 7.4-fold. Besides age, molecular subtype, and staging, diabetes was significantly associated with the response to neoadjuvant chemotherapy, highlighting the importance of elucidating the mechanism by which diabetes may impair the response to neoadjuvant treatment, as well as the importance of prevention and management of diabetes before and during oncologic treatment.