Evaluation of treatment response in patients with geriatric breast cancer receiving neoadjuvant chemotherapy

Aim: Neoadjuvant chemotherapy (NAC) is an established treatment option used to reduce tumour size for patients who want more conservative surgery, as well as to evaluate tumour biology early and plan subsequent modalities according to the response to treatment. However, its use in geriatric patients has not been adequately investigated. In this study, we aimed to evaluate the treatment response (pCR) and side effects in geriatric breast cancer patients receiving NAC in comparison with non-geriatric patients receiving NAC. Materials and Methods: Patients who applied to the KTU Faculty of Medicine, Department of Internal Medicine, Division of Medical Oncology between 01.01.2018 and 01.01.2023, who were 18 years of age or older, who received neoadjuvant chemotherapy and then underwent surgery, whose pathology records were available in our hospital or could be accessed from database were included in the study. The dates of breast cancer diagnosis, recurrence-metastasis status and death dates of the patients between 2018-2023 were accessed from hospital records and DNS (death notification system) database. In addition, the types of neoadjuvant chemotherapy regimens, ECOG scores at the start of chemotherapy, pre- and post-operative hormone receptor status, TNM and clinical stages, histology of pathology material were recorded. The main subject of our study; Pathological complete response data was grouped as the following: Complete response/Partial response/No response Absence of any residue in the breast and axilla was considered as pathological complete response. Results:197 (72.7%) of cases were younger than 65 years and 74 (27.3%) of cases were 65 years and older. The mean age was 52.66±12.89 years (Minimum=27.00-Maximum=92.00) and the mean follow-up period from the date of initial diagnosis was 31.51±17.07 years (Med.=29.82: 1.68-71.70). Chi-Square test showed that the rate of nephrotoxicity side effects in geriatric patients was statistically significantly higher (p<0.001) compared to patients younger than 65 years. The rates of chemotherapy postponement and dose reduction were found to be statistically significantly different (p<0,001) in geriatric patients compared to patients aged 65 years and younger. In the case of pathological complete response (pCR), which is the main subject of our study, according to the Chi-Square test, it was found that the pCR rate of the patient group under 65 years of age was statistically significantly higher than the geriatric patient group (p=0,006). There was no significant difference between the age groups in terms of axillary lymph node positivity, lymph node dissection, lymphovascular and perineural invasion, surgical margin clearance and skin invasion. Chi-Square Test showed that the rate of radiotherapy was statistically significantly higher (p=0.013) in patients under 65 years of age compared to patients 65 years of age and older. According to the Chi-Square test, it was found that there was no statistically significant difference in the rates of subsequent metastasis between age groups ( p= 0,841). No significant difference was found between age groups in terms of metastasis. No significant difference was found between age groups in terms of metastasis sites. There was no statistically significant difference (p=0.287) between geriatric patients and patients under 65 years of age in terms of overall survival. Conclusion: In our study, pCR rate after NAC was found to be significantly higher in the group under 65 years of age compared to geriatric patients. In addition, nephrotoxicity side effect rates were found to be significantly higher in the geriatric patient group, and chemotherapy postponement and dose reduction were found to be significantly higher in the geriatric patient group. Since there are few studies comparing patients receiving neoadjuvant treatment in terms of pathological response in relation to age, we think that our study sheds light on the literature. Key Words:Breast cancer,Geriatric patient, Neoadjuvant chemotherapy, Pathological complete response