Gauthe M, et al. - In a series of patients who underwent radiation-based therapy for anal canal squamous cell carcinoma, researchers evaluated the prognostic value of cytokeratin 19 fragment 21–1 (CYFRA 21-1), using the Kaplan–Meier method and Cox regression analysis to assess survival rates and prognostic variables for prediction of outcomes, respectively. A significant correlation of pre-treatment serum CYFRA 21-1 levels with tumour stage was noted as well as normal post-treatment serum CYFRA 21-1 level was found to be significantly correlated with tumour complete response. Overall, as a marker for the monitoring of anal squamous cell carcinoma patients, serum CYFRA 21-1 appeared to have utility. Also, correlation of elevated post-treatment value with treatment failure was noted.