High dose rate brachytherapy (HDR-BT) in locally advanced oesophageal cancer. Clinic response and survival related to biological equivalent dose (BED).

INTRODUCTION: Ninety percent of oesophageal cancers are locally advanced at diagnosis, and treatment yields discouraging results. High dose rate brachytherapy (HDR-BT) permits an increment of local doses without a significant increment of toxicity. The goal of our study is to compare different HDR-BT fractions and assess global survival (GS) and cause-specific survival (CSS).
MATERIAL AND METHODS: Twenty-six patients were treated for locally advanced oesophageal cancer with chemotherapy concomitant with conformal three-dimensional radiotherapy (C3DR) from January 1994 to December 2000. Of this group, 96.2% were males, mean age 63.08 years; the most frequent location was medium third, for 50% of cases. Eighty-four percent of cases were G2-3 epidermoid carcinomas. The administration consisted of 44.2 Gy with C3DR and 5 applications of HDR-BT of 500 cGy each.
RESULTS: Actuarial GS and CSS at 5 years is 10.18% and 12.96%, a mean survival of 25.68 and 29.14 months respectively. The following factors (C3DR total dose, fraction dose and total dose of HDR-BT, number of applications, active length of application, total dose of C3DR plus HDR-BT, and BED of HDR-BT) are evaluated to find if they have an influence on treatment response, GS and actuarial CSS. The only result that yields statistical significance, in univariant analysis, is the active length in HDR-BT, thus for a greater active length of application, a minor response is obtained and GS diminishes (p=0.05). We grouped BT fractions on biological equivalent dose (BED) into: <28, 28-33 and >33 Gy; mean survival and GS at 5 years increases with BED>or=28 Gy (p=0.016).
CONCLUSION: Tumour response increases (complete and partial) when BED on HDR-BT is increased, regardless of the fraction employed. A BED higher than 28 Gy yields a significant increase of mean survival and GS at 5 years (p=0.016).