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

Objective: The eosinophil to lymphocyte ratio (ELR) was examined because it was considered to be a simple, affordable and easily accessible marker that can contribute to previously found markers to predict neoadjuvant chemotherapy (NAC) response and prognosis in patients diagnosed with locally advanced breast cancer (LABC). Methods: Overall 102 female patients over the age of 18 who were diagnosed with LABC and received NAC at the Dokuz Eylul University Faculty of Medicine, Department of Internal Medicine, Division of Medical Oncology between 2010 and 2019 were included in the study. Demographic, clinical, pathological and laboratory data of the patients were reviewed retrospectively. Laboratory data (leukocyte count, eosinophil count and percentage, lymphocyte count and percentage, ELR and eosinophilxlymphocyte) were evaluated before chemotherapy, before surgery and before recurrence. Univariate and multivariate regression analyzes were performed to determine the most important risk factors for pathological complete response (pCR), recurrence and mortality. Kaplan-Meier survival analysis method was used to determine the effects of these factors on PFS (progression-free survival) and OS (overall survival). Results: Median age at diagnosis was 50.8±13.0 years, follow-up time was 41.0±27.0 months; the mean time from NAC to operation was calculated as 7.9±2.5 months. The mortality rate was 10.8%, the recurrence rate was 14.7%, and pCR rate was 27.5%. ELR and eosinophilxlymphocyte parameters before and after NAC; no statistically significant difference was found in terms of the value of pCR in predicting recurrence and mortality. Clinical and pathological features with the most important predictive value for pCR; low number of positive lymph nodes (LN) (OR=0.342, p=0.04) and ER negativity (OR=2.6, p=0.035). Risk of recurrence in patients with positive LN count of three or more; 3.8 times more (OR=3.8, p=0.008), PFS duration was found to be shorter. The risk of recurrence in patients with a lymphocyte percentage of 26.75 and below before NAC; 4.2 times more (OR=4.2,p=0.016), PFS time was found to be shorter. Conclusion: When the more patient number and the long follow-up period are evaluated; it is thought that markers such as peripheral blood ELR or eosinophilxlymphocyte can be used as affordable, easily accessible predictive and prognostic markers in predicting NAC response. Keywords: locally advanced breast cancer, neoadjuvant chemotherapy, pathological complete response, prognostic marker, recurrence