Postoperative adjuvant intensity-modulatd radiotherapy for radically resected rectal adenocarcinoma: data from everyday practice

Abstract

Introduction: Adjuvant radiochemotherapy is a standard treatment in patients with surgically treated stage II or III rectal adenocarcinoma who did not undergo neoadjuvant radiotherapy. Intensity-modulated radiation therapy (IMRT) was only marginally investigated in postoperative setting.

Material and methods: A longitudinal observational analysis was conducted in patients with radically resected stage II or III rectal adenocarcinoma treated with IMRT at the University Clinic for Radiotherapy and Oncology as part of the adjuvant postoperative treatment. The dose-volume parameters of the radiotherapy plans, as well as acute side effects of 40 patients were analyzed.

Results: The average dose received by the target volume was 49.95 Gy (range 27-54 Gy). The mean volume of peritoneal cavity receiving 45 Gy (V45) was 102.73 cm3 (±52.10), V30 for pelvic bones was 38.3% (±5.48), V40 for bladder 52.48% (±10.9). The most frequent acute side effects were diarrhea in 17 (42.5%), lymphopenia in 34 (85%) and thrombocytopenia in 26 patients (65%). Most of the side effects were self-limiting and caused disruption of the radiation treatment only in 3 patients (7.5%).

Conclusion: Integrating IMRT in the adjuvant treatment of locally advanced rectal cancer provides a good dose distribution and organs at risk sparing. The treatment is well tolerated, the side effects are mainly of lesser degrees and easily managed. A prospective trial comparing IMRT with 3-dimensional conformal radiotherapy is needed to assess whether IMRT offers a better perspective for adjuvant treatment.