Pathological complete response rate to anthracycline versus non−anthracycline based chemotherapy regimens in localized and regional HER2 neu positive breast cancer.

Abstract

e12632 Background: Debate over the need of anthracycline as part of neoadjuvant chemotherapy in HER2-neu early breast cancer was addressed in many trials with results favoring similar outcomes with or without anthracycline. This was not adopted fully in Saudi Arabia because of concern regarding ethnic differences in response to treatment. We conducted this retrospective analysis to evaluate if there is any difference in pathological complete response rate (PCR) in patients with early HER2-neu positive breast cancer depending on neoadjuvant chemotherapy regimen. Methods: Patients with HER2-neu positive early breast cancer who were treated with neoadjuvant chemotherapy at Johns Hopkins Aramco Healthcare (JHAH) facility between the year 2018 and 2022 were all evaluated for pathological subtype, HER2-neu status and type of neoadjuvant chemotherapy administered. Pathological response status was evaluated in all patients and PCR was measured to see if there was any difference depending on the use of anthracycline (AC) or non-anthracycline (non-AC) based chemotherapy regimen. Patient demographics, tumor characteristics, clinical stage, treatments and outcomes were collected via JHAH’s oncology registry. Categorical variables are reported as frequencies and percentages. The association between chemotherapy regimen AC vs non-AC based and PCR was analyzed using Fisher Exact Test. p-value <0.05 was considered statistically significant. Analyses were conducted using JMP version 15. Results: In this study 59 HER2-neu positive early breast cancer patients were identified. We examined their clinical characteristics and treatment outcomes. Median age was 57. The most prevalent histology was invasive carcinoma of no special type (79.66%), Estrogen receptor positivity was observed in 72.88% of patients, while progesterone receptor positivity was seen in 62.71% of cases. Majority of patients were alive (96.61%) at the time of data collection. There was no significant difference in clinical stage in both groups. The association between chemotherapy type and pathological response was assessed. Among patients receiving AC chemotherapy (n=29), 55.17% achieved PCR, while for patients receiving Non-AC chemotherapy (n=30), the PCR rate was 50%. However, this difference was not statistically significant (p-value = 0.8). Conclusions: In our cohort of HER-neu positive early breast cancer patients who received neoadjuvant therapy there seems to be no significant difference in PCR with AC or Non-AC based chemotherapy regimens. This is concordant with the international trends.