Radiation Therapy for Rectal Cancer: An ASTRO Clinical Practice Guideline Focused Update

Purpose: With the results of several recently published clinical trials, this guideline focused update provides evidence-based recommendations for the indications and dose-fractionation regimens for neoadjuvant radiation therapy (RT), optimal sequencing of RT and systemic therapy in the context of total neoadjuvant therapy (TNT), and considerations for selective omission of RT and surgery for rectal cancer.

Methods: The American Society for Radiation Oncology convened a multidisciplinary task force to update 3 key questions that focused on the role of RT for patients with operable rectal cancer. The key questions addressed (1) indications for neoadjuvant RT, (2) selection of neoadjuvant regimens, and (3) indications for consideration of a nonoperative management (NOM) or local excision approach after definitive/preoperative chemoradiation. Recommendations were based on a systematic literature review and created using a predefined consensus-building methodology and system for quality of evidence grading and strength of recommendation.

Results: For patients with stage II-III rectal cancer, neoadjuvant RT was strongly recommended; however, among patients deemed at lower risk of locoregional recurrence, consideration of omission of neoadjuvant RT was conditionally recommended in favor of neoadjuvant chemotherapy with a favorable treatment response or upfront surgery. For patients with T3-T4 and node-positive rectal cancer undergoing neoadjuvant RT, a TNT approach was strongly recommended. Among patients with higher risk of locoregional recurrence, TNT with chemotherapy before or after long-course chemoradiation was strongly recommended, whereas TNT with short-course RT followed by chemotherapy was conditionally recommended. For patients with rectal cancer for whom NOM is a priority, concurrent chemoradiation followed by consolidation chemotherapy was strongly recommended. Selection of RT dose-fractionation regimen, sequencing of therapies, and consideration of NOM should be determined by multidisciplinary consensus and based on disease extent, disease location, patient preferences, and quality of life considerations.

Conclusions: The task force proposed recommendations to inform best clinical practices on the use of RT for rectal cancer with strong emphasis on multidisciplinary care. Future studies should focus on further addressing optimal treatment regimens to allow for more personalized recommendations based on individual risk stratification and patient priorities regarding quality of life.