Preoperative chemoradiation of locally advanced T3 rectal cancer combined with an endorectal boost.

Abstract

To investigate the effect and feasibility of concurrent radiation and chemotherapy combined with endorectal brachytherapy in T3 rectal cancer with complete pathologic remission as end point. The study included 50 patients with rectal adenocarcinoma. All patients had T3 tumor with a circumferential margin 0-5 mm on a magnetic resonance imaging scan. The radiotherapy was delivered by a technique including two planning target volumes. Clinical target volume 1 (CTV1) received 60 Gy/30 fractions, and CTV2 received 48.6 Gy/27 fractions. The tumor dose was raised to 65 Gy with endorectal brachytherapy 5 Gy/1 fraction to the tumor bed. On treatment days, the patients received uracil and tegafur 300 mg/m2 concurrently with radiotherapy. Forty-eight patients underwent operation. Histopathologic tumor regression was assessed by the Tumor Regression Grade (TRG) system. TRG1 was recorded in 27% of the patients, and a further 27% were classified as TRG2. TRG3 was found in 40%, and 6% had TRG4. The toxicity was low. The results indicate that high-dose radiation with concurrent chemotherapy and endorectal brachytherapy is feasible with a high rate of complete response, but further trials are needed to define its possible role as treatment option.