The choice of a neoadjuvant chemotherapy cycle for breast cancer has significance in clinical practice: results from a population-based, real world study

Objective:Neoadjuvant chemotherapy(NAC)is currently used in both early stage and locally advanced breast cancers.The survival benefits of standard vs.non-standard NAC cycles are still unclear.This study aimed to investigate the relationship between NAC cycles and survival based on real world data.Methods:We identified patients diagnosed with invasive primary breast cancers who underwent NAC followed by surgery.Patients who received at least 4 NAC cycles were defined as having received standard cycles,while patients who received less than 4 NAC cycles were defined as having received non-standard cycles.Kaplan-Meier curves and Cox proportional hazard models were used to estimate the disease-free survival(DFS)and overall survival(OS).Results:Of the 1,024 included patients,700 patients received standard NAC cycles and 324 patients received non-standard NAC cycles.The DFS estimates were 87.1%and 81.0%(P=0.007)and the OS estimates were 90.0%and 82.6%(P=0.001)in the standard and non-standard groups,respectively.Using multivariate analyses,patients treated with standard NAC cycles showed significant survival benefits in both DFS[hazard ratio(HR):0.62,95%confidence interval(CI):0.44–0.88]and OS(HR:0.54,95%CI:0.37–0.79).Using stratified analyses,standard NAC cycles were associated with improved DFS(HR:0.59,95%CI:0.36–0.96)and OS(HR:0.49,95%CI:0.28–0.86)in the HER2 positive group.Similar DFS(HR:0.50,95%CI:0.25–0.98)and OS(HR:0.45,95%CI:0.22–0.91)benefits were shown for the triple negative group.Conclusions:Standard NAC cycles were associated with a significant survival benefit,especially in patients with HER2 positive or triple negative breast cancer.