Serum conversion pattern of SCC-Ag levels between pre- and post-chemoradiotherapy predicts recurrence and metastasis in cervical cancer: a multi-institutional analysis

The value of squamous-cell carcinoma antigen (SCC-Ag) as a tumor marker for cervical cancer is controversial because it is not elevated (> 2 ng/mL) in a quarter of patients at diagnosis. Two hundred ninety one IB-IVA cervical squamous cell-carcinoma patients who underwent definitive chemoradiotherapy (CRT) were included in four tertiary institutions. Serum conversion pattern between pre- and post-treatment SCC-Ag levels was categorized into the following three arms: (1) Consistent Seronegative arm (both ≤ 2 ng/mL); (2) Negative Conversion arm (from > 2 ng/mL to ≤ 2 ng/mL); and (3) Consistent Seropositive arm (both > 2 ng/mL). Median follow-up time was 40.3 months. For Consistent Seronegative (N = 67), Negative Conversion (N = 165), and Consistent Seropositive (N = 59) arms, the 3-year recurrence-free survival (RFS) rates were 79.4%, 62.0%, and 48.4% (P < 0.001) and the 3-year overall survival (OS) rates were 86.3%, 80.6%, and 58.7% (P = 0.001), respectively. The serum conversion pattern of SCC-Ag between pre- and post-treatment was the most significant and potent prognostic factor of RFS (P = 0.001) and OS (P = 0.007) on the multivariate analysis. Simply checking whether SCC-Ag level is above or below 2 ng/mL before and after definitive CRT can provide clinicians with a simple rule-of-thumb for prediction of disease outcome in cervical cancer patients.