ASTRO Releases First Guideline Defining Radiation Therapy’s Role in Gastric Cancer

The American Society for Radiation Oncology (ASTRO) has issued its first clinical guideline dedicated to the use of radiation therapy (RT) in gastric cancer, offering evidence-based recommendations for integrating RT into multidisciplinary care. The guideline appears today in Practical Radiation Oncology.

Gastric cancer remains the fifth leading cause of cancer incidence and death worldwide, with more than 30,000 new U.S. cases expected in 2025. Although overall rates have declined over the past half-century, recent data suggest rising incidence among middle-aged adults. Because many cases are diagnosed at an advanced stage, effective coordination across surgical, medical and radiation oncology is critical.

“Management of gastric cancer is complex and multidisciplinary, and the role of radiation therapy has evolved over the past two decades,” said Christopher G. Willett, MD, FASTRO, chair of the guideline panel. “It requires thoughtful and dynamic integration with the modalities of surgery, chemotherapy, immunotherapy and palliative care.”

Key Recommendations

For resectable disease, the guideline endorses surgery plus perioperative chemotherapy using the FLOT regimen as standard care. Preoperative chemoradiation is advised for patients unable to receive perioperative chemotherapy, to improve the chance of complete tumor removal and reduce early recurrence. It may also support patients with borderline resectable tumors. The document further highlights the expanding role of immunotherapy in first-line treatment and identifies situations where postoperative chemoradiation may benefit select patients.

For unresectable or metastatic disease, definitive chemoradiation is recommended for nonmetastatic patients who cannot undergo surgery, including those with localized recurrences and no prior RT exposure. Palliative RT is strongly recommended for symptom relief—particularly bleeding, obstruction and pain—with reirradiation considered in select cases. For patients with limited metastatic spread, metastasis-directed RT or surgery combined with systemic therapy is conditionally recommended.

“While other societies have published guidelines for gastric cancer, this is the first to clarify the role of radiation therapy across all stages of the disease,” said Christopher J. Anker, MD, vice chair of the panel. “It provides patient-centered, evidence-based recommendations to guide clinical practice.”

The guideline outlines recommended dose and fractionation strategies, treatment volumes and best practices for both definitive and palliative settings. It also highlights modern techniques—such as intensity-modulated RT, image guidance and respiratory motion management—that improve precision and reduce toxicity.

ASTRO emphasizes that treatment decisions should be made collaboratively across specialties, with patients fully informed of risks and benefits.