The effect of peripheral blood eosinophil/lymphocyte ratios on chemotherapy response and prognosis before and after neoadjuvant chemotherapy in patients with locally advanced breast cancer

ABSTRACT BACKGROUND This study aims to examine the peripheral blood eosinophil/lymphocyte ratio (ELR) as a simple, affordable and easily accessible marker to predict neoadjuvant chemotherapy (NACT) response and prognosis in patients with locally advanced breast cancer (LABC). METHODS The study included 102 female patients over the age of 18 who were diagnosed with LABC in 2010-2019 and were treated with NACT at Dokuz Eylül University Faculty of Medicine, Department of Internal Medicine, Medical Oncology. The patients were retrospectively examined for demographic, clinical, pathological and laboratory data. Laboratory data (leukocyte count, eosinophil count and percentage, lymphocyte count and percentage, ELR and eosinophil x lymphocytes) were evaluated before chemotherapy, before surgery and before relapse. Single and multi-variable regression analyses were performed to determine risk factors important for pathological complete response (pCR) and relapse development. The Kaplan-Meier survival analysis method was used to determine the effects of these factors on PFS (progression-free survival). RESULTS The mean diagnostic age was 50.8±13.0 years, the follow-up time was 41.0±27.0 months, and the average time from NACT to operation was 7.9±2.5 months. Mortality rate was 10.8%, relapse rate was 14.7%, and PCR incidence rate was 27.5%. No statistically significant differences were found in the ELR and eosinophil x lymphocyte parameters before and after NACT in terms of their value in pCR and relapse prediction. The most important predictive clinical and pathological features for pCR were found to be low count of positive lymph nodes (LN) (OR = 0.342, p = 0.04) and ER negativity (OR = 2.6, p = 0.035). The risk of recurrence in patients with a positive LN count of three and above was 3.8 times greater (OR = 3.8, p = 0.008) and the duration of PFS was shorter. The risk of recurrence in patients with a pre-NACT lymphocyte percentage of 26.75 and below was 4.2 times greater (OR = 4.2, p = 0,016), and the duration of PFS was shorter. CONCLUSION The study suggests that if more patients are evaluated and over a long follow-up period, markers such as peripheral blood ELR or eosinophil x lymphocyte could be used as affordable, easily accessible predictive and prognostic markers for predicting NACT response.