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.

Interstitial hyperthermia using 27 MHz wire antennas and interstitial photodynamic therapy in a rat rhabdomyosarcoma: phantom and animal studies.

This paper deals with the interaction of interstitial hyperthermia (HT) and interstitial photodynamic therapy (PDT). Its main focus, however, is on a newly developed heating system; phantom studies as well as temperature-response data obtained from the in vivo experiments are presented. Heat was delivered by thin, flexible wire antennas operating at a frequency of 27 MHz. Measurements in muscle-equivalent phantom with infrared thermography were performed. Uniform heating over the inserted length of the antenna was obtained and impedance matching appears possible by simple variable air coils, thereby minimizing the reflected power to less than 20%. Light was obtained from an Argon-Dye laser system tuned to a wavelength of 625 nm at a dose rate of 75-100 mW per fiber to a total incident dose of 900 J from four linear light applicators. An experimental murine tumor (Rhabdomyosarcoma, type R-1) was transplanted in WAG/Rij rats and, after reaching an average diameter of 2 cm, the active component of haematoporphyrin derivative (HPD), Photofrin II, was injected intravenously. The tumors were subsequently implanted with four flexible catheters, through which either light or heat could be applied. Dose-response relationships for PDT alone, HT alone and PDT followed by HT were established with cure as endpoint. The animal experiments showed that with the use of low-frequency wires a good localized heat distribution in the tumors can be obtained. Moreover, this study showed that PDT and HT, in the proper sequence and only when optimal temperatures are reached, result in an augmented cytotoxicity on the tumor cells in vivo; i.e. a cure rate of 41% was obtained.