ASTRO Issues Clinical Guideline on Radiation Therapy for Rectal Cancer
A new clinical guideline from the American Society for Radiation Oncology (ASTRO) provides guidance for physicians who use radiation therapy to treat patients with locally advanced rectal cancer. Recommendations outline indications and best practices for pelvic radiation treatments, as well as the integration of radiation with chemotherapy and surgery for stage II/III disease. The guideline, which replaces ASTRO's 2016 guidance for rectal cancer, was published in Practical Radiation Oncology.
Colorectal cancer is the second most common cause of cancer death in the United States, and half of new colorectal cancer diagnoses are in people age 66 or younger. Rectal cancer diagnoses account for nearly one-third of colorectal cancers; an estimated 43,340 adults will be diagnosed with rectal cancer in 2020. Although rectal cancer incidence and mortality rates have dropped among older adults in recent years, they have increased for those younger than age 55.
Standard treatment for locally advanced rectal cancer generally involves chemoradiation therapy or short-course radiation without chemotherapy, followed by tumor removal surgery and additional chemotherapy. More recently, several trials have shown potential for emerging paradigms, such as changing the sequencing of treatments or omitting portions of treatments for select patients.
The guideline addresses patient selection for radiation therapy, delivery of pelvic radiation treatments, options for nonoperative management of locally advanced rectal cancer, and guidance for follow-up care:
- Neoadjuvant radiation therapy is strongly recommended for patients with clinical stage II/III rectal cancer to reduce their risk of locoregional recurrence. Radiation therapy for locally advanced rectal cancer should be performed before rather than after surgery. Radiation may be omitted in favor of upfront surgery for some patients at low risk of recurrence, after discussion by a multidisciplinary care team. Clinical staging involving a physical exam and pelvic magnetic resonance imaging is critical to determine which patients should receive neoadjuvant radiation therapy.
- For patients who require neoadjuvant radiation therapy, both conventionally fractionated radiation and short-course radiation are recommended equally, given high-quality evidence for similar efficacy and patient-reported quality of life outcomes with each treatment. The guideline specifies optimal dosing, fractionation, and delivery techniques for radiation therapy.
- Recommendations address how to incorporate chemotherapy into the preoperative setting for patients who are at high risk of recurrence and who would likely benefit from the additional treatment using a total neoadjuvant therapy approach. Recommendations also address other sequencing and timing issues for radiation, chemotherapy, and surgery, with specific attention to treatment tolerability and potential downstaging.
- Organ preservation approaches (ie, nonoperative management and local excision) may present an alternative to radical surgery for select patients, especially those who would have a permanent colostomy or inadequate bowel continence after surgery. The guideline outlines specific criteria for situations where surgery can be avoided, as well as long-term surveillance and care for these patients.
Disclosure: For full disclosures of the study authors, visit practicalradonc.org.