ASTRO Releases New Clinical Guidelines for Use of Radiation Therapy in Locally Advanced Rectal Cancer

The updated guidelines outlined indications and best practices for pelvic radiation treatments, as well as the integration of radiation with chemotherapy and surgery for patients with stage II to III disease.

New clinical guidelines from the American Society for Radiation Oncology (ASTRO) published in Practical Radiation Oncology provided guidance for physicians who use radiation therapy to treat patients with locally advanced rectal cancer.1

The updated guidelines, which replace ASTRO’s 2016 guidance for rectal cancer, outlined indications and best practices for pelvic radiation treatments, as well as the integration of radiation with chemotherapy and surgery for patients with stage II to III disease.

“As rectal cancer becomes more of a disease of younger adults, long-term survivorship and quality of life considerations become even more important,” Prajnan Das, MD, MPH, chair of the rectal guideline task force, as well as professor and chief of gastrointestinal radiation oncology at The University of Texas MD Anderson Cancer Center in Houston, said in a press release.2 “Part of our motivation was to create guidelines that provide options for different treatments that could potentially improve survival rates and also help preserve patients' quality of life.”

More specifically, the recommendations in the guideline address patient selection for radiation therapy, delivery of pelvic radiation treatments, options for non-operative management of locally advanced rectal cancer, and guidance for follow-up care. Key recommendations with the updated guidelines include:

  • For patients with clinical stage II-III rectal cancer, neoadjuvant radiation therapy is strongly recommended to reduce their risk of locoregional recurrence. Moreover, the guidelines suggest that radiation therapy for locally advanced rectal cancer should be performed before rather than after surgery. Radiation may also be omitted in favor of upfront surgery for some patients at low risk of recurrence, after discussion with a multidisciplinary care team. Nonetheless, clinical staging involving a physical exam and pelvic MRI is crucial in determining which patients should receive neoadjuvant radiation therapy.
  • Both conventionally fractionated radiation and short-course radiation are recommended equally for patients who require neoadjuvant radiation therapy, given that researchers have observed high-quality evidence for similar efficacy and patient-reported quality of life outcomes with each treatment. The guidelines also specifically outline optimal dosing, fractionation, and delivery techniques for radiation therapy.
  • The updated recommendations also addressed how to incorporate chemotherapy into the pre-operative setting for patients who are at high risk of recurrence and who would likely benefit from additional treatment using a total neoadjuvant therapy (TNT) approach. Further, the guidelines highlighted other sequencing and timing issues for radiation, chemotherapy and surgery, with specific attention given to treatment tolerability and potential downstaging.
  • Organ preservation approaches (i.e., non-operative management and local excision) may present an alternative to radical surgery for select patients according to the ASTRO recommendations, especially those who would have a permanent colostomy or inadequate bowel continence after surgery. Notably, the guideline lays out distinguishing criteria for situations where surgery can be avoided, as well as long-term surveillance and care for such patients.

“Different treatments are appropriate for different patients, and the oncology field at large is moving toward personalized care,” Jennifer Y. Wo, MD, vice chair of the rectal guideline task force and associate professor of radiation oncology at Harvard Medical School and Massachusetts General Hospital in Boston, said in the release. “Some patients may need less than what is considered a typical course of treatment, while some patients may need more. This guideline focuses on providing options that can be tailored to patients' characteristics and their wishes.”

Importantly, though the updated guidelines were completed before the coronavirus disease 2019 (COVID-19) pandemic, the recommendations outlined by ASTRO can still guide clinics as they continue to care for patients. Furthermore, to reduce how frequently patients needed to come into the clinic for treatment, many institutions moved toward short-course radiation in the early months of the pandemic, which aligns with the guideline's recommendations.

“We have yet to see the true impact of COVID-19, but we know that interruptions in screening likely will lead to fewer patients receiving treatment when their disease is more manageable,” Wo added. “And if that does happen and we start seeing patients with more advanced disease, then the parts of the guidelines that specifically address treatment for high-risk patients will become even more important."


1. Wo JY, Anker CJ, Ashman JB, et al. Radiation Therapy for Rectal Cancer: Executive Summary of an ASTRO Clinical Practice Guideline. Practical Radiation Oncology. doi: 10.1016.j.prro.2020.08.004

2. ASTRO issues clinical guideline on radiation therapy for rectal cancer [news release]. Arlington, Virginia. Published October 21, 2020. Accessed October 29, 2020.