Measurement of serum squamous cell carcinoma antigen levels as a predictor of radiation response in patients with carcinoma of the uterine cervix.

Background: Optimal timing of the measurement of serum squamous cell carcinoma (SCC) antigen during radiation therapy (RT) and its significance for predicting the response of cervical carcinoma patients as early as possible remain unknown.
Methods: Sixty-three patients with SCC of the uterine cervix who received RT only were studied. Patients were treated with a combination of external beam irradiation and high-dose rate intracavitary irradiation. The serum SCC antigen level was measured before, every 2 or 3 weeks during, and 1 or 2 months after RT. Clinical outcome was divided into complete response and incomplete response.
Results: Forty-seven patients (74.6%) had serum SCC antigen levels 1.5 ng/mL (the reference value) before RT. Normalization of serum SCC antigen levels at the end of RT were found to be significantly correlated with complete response in the SCC-positive patients. It was especially noted that in patients with serum SCC levels between 5-30 ng/mL before RT, a > 70% decrease in the serum SCC antigen level at 4 weeks was correlated significantly with complete response. In this group, a significant correlation also was found between a > 70% decrease in serum SCC level at 4 weeks and the normalization of SCC at the end of RT.
Conclusions: The current study data suggest that the serum SCC antigen level not only before, but also during and at the end of RT can predict the response of patients with cervical carcinoma and help in identifying those patients who are at high risk of local recurrence and/or distant metastasis.
(Copyright 2003 American Cancer Society.)