Late adverse effects of radiation therapy for rectal cancer - a systematic overview

Purpose. The use of radiation therapy (RT) together with improvement in the surgical treatment of rectal cancer improves survival and reduces the risk for local recurrences. Despite these benefits, the adverse effects of radiation therapy limit its use. The aim of this review was to present a comprehensive overview of published studies on late adverse effects related to the RT for rectal cancer. Methods. Meta-analyses, reviews, randomised clinical trials, cohort studies and case-control studies on late adverse effects, due to pre- or postoperative radiation therapy and chemo-radiotherapy for rectal cancer, were systematically searched. Most information was obtained from the randomised trials, especially those comparing preoperative short-course 5x5 Gy radiation therapy with surgery alone. Results. The late adverse effects due to RT were bowel obstructions; bowel dysfunction presented as faecal incontinence to gas, loose or solid stools, evacuation problems or urgency; and sexual dysfunction. However, fewer late adverse effects were reported in recent studies, which generally used smaller irradiated volumes and better irradiation techniques; although, one study revealed an increased risk for secondary cancers in irradiated patients. Conclusions. These results stress the importance of careful patient selection for RT for rectal cancer. Improvements in the radiation technique should further be developed and the long-term follow-up of the randomised trials is the most important source of information on late adverse effects and should therefore be continued