The American Society for Radiation Oncology (ASTRO) has published its first clinical guideline focused on radiation therapy for gastric cancer, clarifying its role in the management of all stages of the disease.

“Over the past decade, several major clinical trials have explored new ways to treat localized gastric cancer, both in cases that can be potentially resectable or locally unresectable,” Christopher Willett, MD, chair of the guideline expert panel, and Christopher Anker, MD, the panel’s vice chair, noted in an email to Medscape Medical News.

For patients with resectable disease, they said, recent trials have shown that treatment plans relying primarily on systemic therapy are either superior to or noninferior to approaches that combine systemic therapy with radiation.

And those findings are now changing patient care, according to Willett, of Duke University in Durham, North Carolina, and Anker, of the University of Vermont Cancer Center in Burlington, Vermont.

“We felt it was the right time to develop a guideline to help clinicians…navigate these shifts and choose the most effective treatment strategies for patients, with a focus on when radiation may be an appropriate option,” they said. 

Gastric cancer is the fifth most common cancer worldwide, with more than 30,000 new diagnoses estimated in 2025 among US adults. 

According to ASTRO, overall rates of gastric cancer have declined over the past 50 years, although recent studies suggest that cases may be increasing among middle-aged adults. In the US, gastric cancers are often diagnosed at an advanced stage, and typically require coordination across radiation, surgical, and medical oncology.

The new ASTRO guideline, published online in Practical Radiation Oncology, was based on a systematic review of research published from 2001 through mid-2025.

Key takeaways include:

• For patients with resectable gastric cancer, surgery and perioperative chemotherapy (fluorouracil, oxaliplatin, and docetaxel given before and after surgery) are the standard-of-care.
• For patients who are not candidates for perioperative chemotherapy, presurgical radiation therapy with concurrent chemotherapy is recommended to help achieve negative surgical margins with the goal of reducing the risk for early recurrence.
• The guideline addresses the evolving role of immunotherapy as a first-line treatment, as well as the use of chemoradiation after surgery for select patients. Chemoradiation may also be considered presurgery for certain patients receiving perioperative chemotherapy for borderline resectable disease to increase the chances of complete resection.
• For patients with nonmetastatic gastric cancer who decline or are not good candidates for surgery, definitive radiation therapy with concurrent chemotherapy is recommended. That approach, Willett and Anker said, “can result in durable long-term control of disease both at diagnosis and if no prior radiation was given, at the time of a recurrence.” The guideline also includes a treatment algorithm for managing locally advanced disease.
• For patients with locally advanced or metastatic cancer who are not eligible for curative therapy, palliative radiation therapy is recommended and can be effective in providing relief from bleeding, pain, obstruction, and other symptoms. Occasionally, re-irradiation may be considered for symptomatic patients, Willett and Anker said.
• For patients with gastric cancer that has metastasized to a limited number of sites outside of the stomach, radiation therapy or surgery for all visible metastases combined with systemic therapy is conditionally recommended.

The guideline contains details regarding appropriate radiation targets, dose, and fractionation, as well as best practices for treatment planning and delivery of definitive and palliative radiotherapy — including newer techniques such as intensity modulated radiation therapy, image guidance and respiratory management.

An overarching theme is the importance of shared decision-making at all stages.

“Care decisions should involve the patient with guidance from providers from all treating disciplines, with a full discussion of risks and benefits to determine the best goal-concordant approach for the patient,” Willett and Anker stressed. 

The guideline was developed in collaboration with the American Society of Clinical Oncology, the European Society for Radiotherapy and Oncology (ESTRO), and the Society of Surgical Oncology (SSO). It is endorsed by ESTRO, SSO, the Royal Australian and New Zealand College of Radiologists and the American Radium Society.

This research had no commercial funding. Disclosures for the expert panel are available with the original article.