Abstract: Objective The aim of this study was to investigate the effect of the atherogenic index of plasma(AIP)on overall survival(OS),disease-free survival(DFS),and pathological complete response(pCR)rate of breast cancer patients receiving neoadjuvant chemotherapy(NACT). Methods This study was a retrospective analysis,including 247 breast cancer patients who received NACT at Harbin Medical University Cancer Hospital from May 2014 to July 2023.Clinical data of patients were collected,and baseline AIP based on preoperative blood lipid indicators was calculated.Patients were divided into the low and high AIP groups based on the median baseline AIP,and the differences in clinical data were compared between the two groups.Patients were further stratified according to the treatment regimens and hormone receptor(HR)status,and analyze the differences in pCR rates between different stratifications.Cox regression models were used to analyze the factors influencing OS and DFS,and to compare the differences in OS and DFS curves between the high-and low-AIP groups.Restricted cubic spline(RCS)models were further constructed to evaluate the potential nonlinear impact of baseline AIP and survival prognosis. Results A total of 247 patients were enrolled,including 123 in the high AIP(＞-0.044)group and 124 in the low AIP(≤-0.044) group.Compared with the low AIP group,patients in the high AIP group had significantly higher BMI and breast-conserving surgery rates(P＜0.05),while there were no significant differences in other baseline characteristics(P＞0.05).Multivariate Cox regression analyses revealed that AIP and p53 status were independent prognostic factors for patient OS(P＜0.05),while AIP,tumor TNM stage,and p53 status were independent influencing factors of patient DFS(P＜0.05).Kaplan-Meier survival analysis showed that the OS and DFS of patients in the low AIP group were significantly better than those in the high AIP group(P＜0.05).There was no statistically significant difference in pCR rates between the low AIP group and the high AIP group(P=0.537).There was no statistically significant difference in pCR rates between the low and high AIP groups in each treatment subgroup,HR-positive subgroup,and HR-negative subgroup(P＞0.05).The RCS model analysis showed a significant positive linear correlation between AIP and OS(P_linearity=0.005,P_nonlinearity=0.188),while no significant linear or nonlinear relationship was observed between AIP and DFS(P_linearity=0.063,P_nonlinearity=0.135). Conclusion There is a significant positive linear correlation between baseline AIP and OS;No significant linear or nonlinear relationship was found between AIP and DFS.Elevated AIP indicates poor survival outcomes.The baseline AIP can be used as a potential prognostic indicator for breast cancer patients undergoing NACT.

Key words: Breast cancer, Neoadjuvant chemotherapy, Plasma atherosclerosis index, Prognosis, Pathological complete response