Peripheral Blood Lymphocyte and Eosinophil Dynamics with Chemotherapy and Pembrolizumab in Cervical Cancer

Background Cervical cancer poses a significant global health burden, particularly in its metastatic and recurrent forms, for which treatment options are limited. Although immune checkpoint inhibitors (ICIs) such as pembrolizumab have improved outcomes, predictive markers for efficacy are still undefined. This retrospective study investigated changes in peripheral blood eosinophil and lymphocyte counts as potential prognostic indicators in patients with metastatic or recurrent cervical cancer undergoing pembrolizumab-based therapy. Methods Forty-one patients treated with pembrolizumab plus taxane-platinum chemotherapy (± bevacizumab) were analyzed. Peripheral blood eosinophil and lymphocyte counts were measured before and three weeks after treatment initiation. Statistical analyses included Kaplan–Meier curves, Cox regression, and log-rank tests. Results Immune-related adverse events ≥ Grade 2 emerged as a significant independent factor associated with prolonged progression-free survival (PFS) in this cohort (p = 0.014). Patients with decreased eosinophil count ratios post-treatment demonstrated longer PFS, particularly among those with recurrence and those who had received prior radiotherapy (p < 0.001). Conversely, increased lymphocyte count ratios correlated with improved PFS in patients undergoing primary treatment (p = 0.018). Conclusion Changes in peripheral eosinophil and lymphocyte counts following pembrolizumab initiation may serve as predictive indicators of treatment efficacy in specific cervical cancer subgroups. Incorporating these hematologic parameters could help optimize patient selection and therapeutic strategies. Further research is needed to clarify their role as predictive markers of pembrolizumab efficacy in cervical cancer.