Radiation Therapy for Gastric Cancer: An ASTRO Clinical Practice Guideline.

[PURPOSE] This guideline provides evidence-based recommendations addressing the indications for radiation therapy (RT) for gastric cancer in a variety of clinical settings, ranging from patients with resectable locoregional disease to metastatic and symptomatic disease.

[METHODS] The American Society for Radiation Oncology convened a task force to address 3 key questions: (1) indications for and timing of RT for patients with resectable and nonmetastatic gastric cancer; (2) indications for and timing of RT in patients with unresectable locoregional disease, oligometastases, and/or requiring palliation; and (3) appropriate RT dose-fractionation regimens, target volumes, and techniques in these clinical settings. Recommendations are based on a systematic literature review and were created using a predefined consensus-based methodology with a system for grading evidence quality and recommendation strength.

[RESULTS] Multidisciplinary evaluation and decision-making are recommended for all patients. For patients with cT2-4 and/or N+ resectable gastric cancer, perioperative chemotherapy is recommended, preferably FLOT (5-fluorouracil, leucovorin, oxaliplatin, and docetaxel). Recently, perioperative durvalumab and FLOT has shown a significant improvement in event-free survival versus FLOT only for patients with resectable disease and is now being adopted as a standard of care. Preoperative chemoradiation is recommended for patients who are not candidates for perioperative chemotherapy and conditionally recommended if there is concern for a margin-positive (R1) or incomplete (R2) resection. Postoperative chemoradiation is conditionally recommended for patients who are not candidates for perioperative or postoperative chemotherapy or if a suboptimal resection was done (eg, <D2 or R1-R2) for those who proceeded directly to surgery. Definitive chemoradiation may provide durable control for nonmetastatic patients who are inoperable either at initial diagnosis or at the time of locoregional recurrence. For patients with oligometastatic gastric cancer, metastasis-directed therapy along with systemic therapy is conditionally recommended. Palliative RT is efficacious for patients with bleeding, pain, and obstruction. Target coverage goals and dose guidance for normal tissues are provided.

[CONCLUSIONS] These evidence-based recommendations guide clinical practice on the use of RT for gastric cancer. Future studies will further refine the indications and role of RT in the management of these patients.