Relationship of circulating immune cells with lifestyle factors and cancer recurrence in early-stage breast cancer.

PURPOSE: To evaluate the relationship of circulating immune cells with recurrence and metabolic/lifestyle factors in patients with early-stage breast cancer. METHODS: Patients with early-stage breast cancer were identified from the electronic record and institutional registry. Lymphocyte and monocyte counts were obtained from blood samples at time of diagnosis prior to any chemotherapy. Correlations between lymphocyte and monocyte and recurrence were assessed in the entire cohort and among obese patients, those reporting alcohol consumption and smoking. Competing risk regression was used to analyze time to recurrence. RESULTS: A total of 950 patients with ≥ 5 years of follow-up were identified; 433 had complete data and were eligible for analysis. 293 (68%) had hormone receptor-positive breast cancer, 82 (19%) HER2 positive, and 53 (13%) triple negative. Patients in the highest quintile of lymphocytes compared to the lowest quintile had lower risk of recurrence (subhazard ratio (SHR) = 0.17, 95% CI [0.03-0.93], p = 0.041) while patients in the highest quintile of monocytes had lower risk for recurrence (SHR = 0.19, 95% CI [0.04, 0.92], p = 0.039). Higher monocytes were more strongly associated with lower recurrence among those reporting alcohol consumption (HR = 0.10, 95% CI [0.01, 0.91], p = 0.04). In obese patients, higher lymphocytes were associated with lower risk of recurrence (p = 0.046); in non-obese patients, higher monocytes were associated with lower risk of recurrence (p = 0.02). There were no correlations among patients who reported tobacco use. CONCLUSIONS: High lymphocyte and monocyte counts are associated with lower recurrence rate in early-stage breast cancer, particularly in obese patients and those reporting alcohol consumption.