Serum SCCA as an Early Indicator of Recurrence in Cervical Cancer.

PURPOSE/OBJECTIVE(S) Patients with recurrence of cervical cancer after definitive radiation therapy (RT) have < 5% long-term survival. Early detection of asymptomatic recurrence may provide an opportunity for salvage. Serum squamous cell carcinoma antigen (SCCA) is an effective biomarker for response to RT and overall prognosis. Retrospective studies indicate that elevated serum SCCA in the post-RT surveillance setting may also be useful to detect asymptomatic recurrence. We hypothesized that elevated serum SCCA at follow-up is a specific indicator of recurrence after definitive RT. MATERIALS/METHODS Serum SCCA (fuSCCA) values measured during the surveillance of patients treated with definitive-intent RT from 2007-2019 were retrospectively analyzed. Serum SCCA was measured by ELISA in a CLIA-certified lab (normal range 0.0-2.2 ng/mL), and was recorded along with patient and tumor factors. Follow-up consisted of history, physical examination, serum SCCA, and imaging when indicated. Recurrence was confirmed pathologically when possible. FuSCCA was defined as the last available value, or as the value closest to the date of recurrence (no more than 6 months prior and 3 weeks after). Sensitivity (Se), specificity (Sp), positive predictive value (PPV) and negative predictive value (NPV) of fuSCCA was determined for recurrence. Analysis was performed for the whole cohort and for a subgroup of patients with available pretreatment SCCA values. Difference in fuSCCA between patients with and without recurrence was compared using a Student's t-test. RESULTS 258 patients were identified with any follow-up SCCA value, 227 with fuSCCA as defined above. Mean age at diagnosis of the whole cohort was 52.7 years. FIGO stage was IB in 19.8%, IIB in 22.9%, IIIC1 in 39.1%, and IIIC2 in 13.2% of patients. After a median of follow-up 50.4 months (range 1.4 - 147.7), 67.1% of patients had no evidence of disease, 6.2% were alive with disease, 21.7% had died of cervical cancer, and 5.0% had died of intercurrent disease. Mean fuSCCA was 0.9 ng/mL (range 0-26.6) for 175 patients with no recurrence and 6.0 ng/mL (range 0-97) for 52 patients with recurrence (two-tailed P = 0.02). Se, Sp, PPV, and NPV of last fuSCCA for recurrence all patients and those with elevated pretreatment serum SCCA is shown in Table 1. Of 81 patients with normal pre-treatment SCCA only two had an elevated value at any point during surveillance, one of whom experienced recurrence. CONCLUSION For patients with elevated pre-treatment serum SCCA, surveillance serum SCCA is an inexpensive and accessible test with high specificity and negative predictive value for recurrence. Surveillance of serum SCCA is of limited utility in patients with normal pre-treatment values.