Is radiation therapy required for patients with intermediate-risk rectal cancer?

Randomized trials have demonstrated that radiation therapy improves local control in patients with rectal cancer. Because pelvic irradiation may result in acute and/or late morbidity, identification of patients with the highest probability of benefiting from this therapy would be optimal. Though radiation is usually recommended for patients with tumors invading through the muscularis propria into the mesorectum with or without lymph-node involvement, several studies suggest that patients with only one of these risk factors may comprise a more favorable risk group who may not require radiation as part of their overall management. Current data permit identification of these patients, but no randomized studies have yet demonstrated that selected patients with locally advanced rectal cancer can safely be spared adjuvant or neoadjuvant radiation.