Prognostic factors derived from a prospective database dictate clinical biology of anal cancer: the intergroup trial (RTOG 98-11).

BACKGROUND: Only 4 prospective randomized phase 3 trials have been reported for anal cancer. A prognostic factor analysis for anal cancer from a prospective database has been published from only 1 study (N = 110). To confirm and uncover new prognostic factors, we analyzed the prospective database of intergroup RTOG 98-11. METHODS: Univariate and multivariate analyses of the baseline characteristics for 5-year overall survival (OS) and disease-free survival (DFS) were carried out. Various combinations of tumor diameter and clinically positive nodes (N(+)) were analyzed to identify subgroups. RESULTS: A total of 644 were assessable and analyzed. Tumor diameter >5 cm was associated with poorer 5-year DFS (P = .0003) and poorer 5-year OS (P = .0031), and N(+) was associated with poorer 5-year DFS (P 5-cm tumor and N(+) had the worst DFS (only 30% at 3 years compared with 74% for the best group; <5 cm primary and N0) and OS (only 48% at 4 years compared with 81% for the best group; <5 cm primary and N0). Men had worse DFS (P = .02) and OS (P = .016). These factors maintained their influence in each treatment arm. CONCLUSIONS: This prospective prognostic factor analysis establishes tumor diameter as an independent prognosticator of poorer 5-year DFS and OS and confirms N(+) and male sex as poor prognostic factors. This analysis also uncovers novel subgroups (derived from combining prognostic factors) with incremental worsening of DFS and OS.

Duke Scholars

Author Christopher G. Willett Radiation Oncology