Persistent lymphopenia after chemotherapy and/or radiotherapy predicted unfavorable outcome in breast cancer patients - a retrospective cohort study

Abstract Background Lymphopenia was often observed during follow-up for cancer patients, this study aimed to evaluate the prognostic value of prolonged lymphopenia for breast cancer patients. Methods This was a retrospective cohort analysis of 296 patients with clinical stage I-III operable breast cancer, who had received chemotherapy and/or radiotherapy. Absolute lymphocyte count lower than 1.1×10^3/ul was defined as lymphopenia. Lymphopenia around the 6th month after chemo-radiotherapy was defined as cohort L, while normal Absolute lymphocyte count was defined as cohort N. Predictors of lymphopenia were assessed using univariate and multivariate logistic regression analyses. Kaplan–Meier and Cox regression analyses were used to evaluate the relationship between the two cohorts. Results The baseline characteristics analysis: comparing to cohort N, cohort L had more Stage III(47.4% vs. 25.5%) and less Stage I cancer(12.3% vs. 20.1%)(p = 0.005), more patients experienced combined chemotherapy regimen(86.0% vs. 69.5%, p = 0.012), more patients experienced radiotherapy(78.9% vs. 64.9%, p = 0.041), and less patients experienced endocrine therapy(54.4% vs. 68.2%, p = 0.049). Multivariate logistic regression analysis revealed two negative independent factors associated with DFS: pTNM staging (stage II vs. I: HR = 5.346, 95% CI: 2.286–12.504, p < 0.001; stage III vs. II: HR = 3.089, 95% CI:1.739–5.487, p < 0.001), and ALC status 6 months after chemo- and/or radiotherapy (HR = 2.445, 95% CI: 1.577–3.788, p < 0.001). Cohort L had significantly shorter DFS (log rank: p < 0.001), as well as significantly shorter OS (log rank: p < 0.001). Conclusion Persistent lymphopenia after chemotherapy and/or radiotherapy was an independent predictor for breast cancer relapse and unfavorable survival.