Abstract:      Background and purpose: Due to the lack of cost-effective pre-treatment predictors for advanced cervical squamous cell carcinomas treated with concurrent chemoradiotherapy (CCRT), both baseline circulating CD4⁺CD25⁺CD127^Low/- regulatory T cell (Treg) count and serum squamous cell carcinoma antigen (SCC-Ag) level were measured for this feasibility study. Methods: Peripheral blood samples were collected from 44 patients with stage Ⅱ_B-Ⅳ_A cervical squamous carcinomas before CCRT. Flow cytometry immunophenotyping and enzyme-linked immunosorbent assay were used for circulating CD4⁺CD25⁺CD127^Low/- Treg count and serum SCC-Ag level testing, respectively. Clinical and pathological characteristics were retrospectively reviewed to analyze the predictive value of the 2 indexes. Results: The baseline circulating CD4⁺CD25⁺CD127^Low/- Treg count was lower in the patient group with positive treatment response than in the group with negative response ［(8.78±2.80)% vs (10.95±2.56)%, P<0.05］, and the serum SCC-Ag level showed no significant difference between the 2 groups. No correlation was detected between these 2 markers (Spearman’rho=-0.093, P=0.540). Determined by plotting receiver operating characteristic curves, the best cut-off points were 9.76% for circulating CD4⁺CD25⁺CD127^Low/- Treg count and 9.50 ng/mL for serum SCCAg level, respectively. Univariate analysis showed that pretherapeutic circulating CD4⁺CD25⁺CD127^Low/- Treg count (OR=1.901, 95%CI: 1.112-3.219, P=0.017), but not serum SCC-Ag level (OR=0.998, 95%CI: 0.001-4.253, P=0.897), was predictive of clinical response to CCRT. Multivariate Logistic regression analysis revealed that pre-treatment CD4⁺CD25⁺CD127^Low/- Treg count was an independent predictor for clinical response to CCRT (OR=3.115, 95%CI: 1.253-7.742, P=0.014). Conclusion: Pretherapeutic circulating CD4⁺CD25⁺CD127^Low/- Treg count is a feasible method to predict clinical response to CCRT in patients with advanced cervical squamous cell carcinomas.

Key words: Advanced uterine cervical squamous cell carcinoma, Concurrent chemoradiotherapy, Regulatory T cells, Serum squamous cell carcinoma antigen