Early Normalization of Squamous Cell Carcinoma Antigen During Combined Chemoradiation Predicts Pathological Response...

Objective: Squamous cell carcinoma antigen (SCC-A) is a widely used biomarker for squamous cell cervical carcinoma and pretreatment elevation is associated with poor prognosis. Normalization during chemoradiation correlates with PET-CT response and survival. This study assessed the prognostic value of SCC-A normalization for biopsy-proven pathological response and survival outcomes. Materials and Methods: This retrospective single-center cohort study included patients with locally advanced or node-positive squamous cell cervical cancer treated with definitive chemoradiation at the Medical University Innsbruck between 2008 and 2023. Eligible patients had baseline SCC-A ≥ 2 ng/mL and at least two additional measurements within 42 days of treatment. SCC-A normalization was evaluated at predefined weekly time points. Associations with biopsy-assessed residual disease, PFS, and OS were assessed. Results: Of 186 screened patients, 83 met the inclusion criteria. Within 42 days, 70% achieved SCC-A normalization, with a median time of 21 days (IQR 19-32). Among predefined time points, normalization by day 28 was associated with reduced odds of residual disease (OR 0.14; 95% CI 0.04-0.44) and improved PFS (HR 0.28; 95% CI 0.12-0.63) and OS (HR 0.37; 95% CI 0.14-0.96), remaining independently significant after multivariate adjustments. Conclusions: SCC-A normalization during chemoradiation is a non-invasive independent biomarker of treatment response. Normalization within 28 days identifies patients at low risk of residual disease, progression, and death, supporting its use for early risk stratification and response monitoring for potential treatment adaptations.