Peripheral lymphocyte count as a prognostic marker in cervical cancer patients treated with immune checkpoint inhibitors: a retrospective study

Pembrolizumab, an immune checkpoint inhibitor (ICI), has revolutionized the treatment of recurrent cervical cancer; however, its benefits are limited. This study investigated whether peripheral lymphocyte count (PLC) is a prognostic factor for ICI in patients with advanced or recurrent cervical cancer. This retrospective study included 47 patients diagnosed with advanced or recurrent cervical cancer, who were treated with pembrolizumab at our hospital between September 2022 and December 2024. The primary outcome was progression-free survival (PFS). The PLC was measured using a blood test conducted immediately before the first administration of pembrolizumab. The optimal PLC cut-off value was determined by using the first quartile point of the PLC distribution. Based on this cut-off value, the patients were allocated into two groups: a normal PLC group (PLChigh) and low PLC group (PLClow). The impact of PLC on PFS was assessed using a Cox proportional hazards regression model using inverse probability of treatment weighting method based on the propensity score, as well as the log-rank test. The median age of the participants was 55 years (interquartile range, 34–84 years). The most common histological type was squamous cell carcinoma (60% of cases). The cut-off value for PLC was set at 710/µL based on the first quartile point. Twelve patients had PLClow (26%) and 35 had PLChigh (74%). Low PLC was significantly associated with shorter PFS (hazard ratio [HR], 2.91, 95% confidence interval [CI], 1.23–6.91, p = 0.013). In the sensitivity analysis, low PLC was also significantly associated with shorter PFS (HR, 4.10; 95% CI, 1.81–9.29, p < 0.001). PLC may have potential as a prognostic marker for immunochemotherapy in patients with advanced or recurrent cervical cancer. Pre-treatment assessment of PLC could be helpful in identifying patients at risk of poor outcomes and in supporting clinical decision-making.