Radiation therapy for cancer of the piriform sinus. A failure analysis.

This paper analyzes the results of 109 piriform sinus (PS) cancers treated between 1973 and 1984 by surgery and/or external beam radiation therapy (EBRT) in a large comprehensive cancer center, and in particular tries to redefine the role of EBRT in the management of these tumors. At the time the policy was to start with EBRT to a dose of 40 Gy. A good response to a first series was to be continued by EBRT (RT-1); in case of poor responding tumors, the primary and neck were to be operated upon (RT-S). Poor responders unfit for S or those refusing S were also carried to a full course of EBRT (RT-2). The RT-S, RT-1, and RT-2 actuarial 5-year locoregional relapse-free survival (LR-RFS) and overall survival (OS) were 60%, 40%, and 20% and 40%, 30%, and 20%, respectively. In a multivariate Cox regression analysis the most important prognostic factor appeared to be N-stage, with hazard ratios of 1.16 (N1), 2.2 (N2), and 3.3 (N3). The RT-S treatment group fared best (hazard ratio 0.5). The risk of relapse for T3,4 was 1.3 times as high as opposed to T1,2. For stage I/II (19/21 treated by EBRT only), a LR-RFS and OS at 5 years of 60% and 40%, respectively, was observed. This analysis supports data for stage III/IV PS cancers to be treated by surgery combined with EBRT; in stage I/II there might be a role for EBRT alone. It is speculated that with further sophistication in RT-techniques, the locoregional control rates by EBRT alone could improve.