Real-world evidence of neoadjuvant chemotherapy for breast cancer treatment in a cohort from a cancer center in Southern Brazil

Introduction: Neoadjuvant chemotherapy is the standard of care for most women with stage II or III breast cancer (BC). Pathological complete response (pCR) is correlated with favorable patient outcomes. As described in real-world data from Brazilian studies, pCR rate ranges from 28-46% in HER2-positive (HER-2+) tumors, 17-20% in luminals and around 22% in triple-negative. Data regarding pCR rate in patients from south of Brazil hasn’t been published so far.

Objective: To describe the pCR rate from patients who started on neoadjuvant chemotherapy during 2022/23 at an academic high-volume breast cancer public hospital in southern Brazil. To analyze the clinical and pathological characteristics of the patients, types of chemotherapy used, toxicity and the percentage of cycle completion. As a secondary objective, we described the time between the diagnosis of breast cancer and the beginning of neoadjuvant chemotherapy.

Methods: this is a retrospective cohort where a review of electronic medical records was performed including all patients whose treatment for BC began in 2022/23. All patients agreed with the consent form.

Results: 91 patients started neoadjuvant chemotherapy. The median age was 52 years (22-79 years) and 71% of patients were white. Regarding the subtype, 43% were luminal B-like, 2% were luminal A-like, 23% were triple negative and 29,6% were HER-2+. Stage II (50%) and stage III (48,3%) composed the majority of cases. Fifty-seven percent received doxorubicin (A) + cyclophosphamide (C) followed by taxane (T). Among HER-2+ disease patients, 74% received AC-T+Trastuzumab (TTZ) and 26% received T+Carboplatin+TTZ. Almost one-third of patients reached a pathological complete response (32,9%). pCR rate was 59,2% in HER-2+, 40% in triple-negative and 11,9% in luminal patients. Seventy-eight patients (85,7%) received all chemotherapy planned cycles and 64,8%, all planned doses. Regarding toxicity, 30 patients had to visit the emergency department for adverse events. Of those, 36% had febrile neutropenia. One death occurred because of hepatotoxicity. Median time between the biopsy and beginning of neoadjuvant chemotherapy was 57 days (20-211 days), and 27 patients (29,6%) started their treatment after 60 days from diagnosis.

Conclusion: in this retrospective analysis we found a larger proportion of pCR among patients with HER-2+ and triple-negative BC compared to retrospective studies with similar chemotherapy regimens.

Corresponding author: Pedro Marchiori Cacilhas (e-mail: pedromcacilhas@gmail.com).