Retrospective evaluation of the effects of comorbidities, demographic characteristics and pathology results on pathological complete response in patients with breast cancer receiving neoadjuvant chemotherapy

Objective: This retrospective study aimed to evaluate the effects of comorbidities, demographic characteristics, and pathological findings on pathological complete response (pCR) in breast cancer patients receiving neoadjuvant chemotherapy (NACT). Materials and Methods: The study included 87 female breast cancer patients over the age of 18 who received NACT and were admitted to the Medical Oncology Clinic of Bolu Abant Izzet Baysal Training and Research Hospital between 2015 and 2025. Patient data were retrospectively analyzed and categorized into two groups based on whether pCR was achieved. Differences between these groups were examined to identify factors associated with treatment response. Results: pCR was achieved in 29.9% (n=26) of the patients, while 70.1% (n=69) did not achieve pCR. No statistically significant differences were observed between the groups in terms of age, number of children, Ki-67 index, tumor size, smoking status, alcohol use, comorbidities or menopausal status. Hormone receptor status, however, demonstrated significant associations with pCR. Estrogen receptor (ER) positivity was 46.2% among patients with pCR and 75.4% among those without pCR. Similarly, progesterone receptor (PR) positivity was lower in the pCR group (34.6%) compared to the non-pCR group (60.7%). HER2/ERBB2 positivity showed a significant relationship with pCR, with 50% of patients achieving pCR being HER2 positive. Conclusion: The findings indicate that comorbidities and demographic data had no significant effect on pCR, ER and PR positivity may reduce the likelihood of achieving pCR, while HER2 positivity appears to be associated with higher pCR rates. These results highlight the importance of molecular subtype in predicting neoadjuvant treatment response.