A new clinical guideline from the American Society for Radiation Oncology (ASTRO) is the first to focus on radiation therapy for patients with gastric (stomach) cancer.

The recommendations outline radiation therapy’s role in multidisciplinary care, including best practices for patient selection, integration with systemic therapy and treatment delivery.

The guideline is published in Practical Radiation Oncology, ASTRO’s clinical practice journal.

Gastric tumours are the fifth most common cause of cancer incidence and death globally, with more than 30,000 new diagnoses estimated in 2025 among American adults.

Overall stomach cancer rates have declined over the past 50 years, though recent studies show that incidence may be increasing among middle-aged adults.

Gastric cancers are often diagnosed at an advanced stage, and typically requiring coordination across radiation, surgical and medical oncology.

Treatments for patients with gastric cancer have advanced significantly over the past decade, driven by improvements in surgery, chemotherapy, immunotherapy and radiation therapy.

For patients with resectable disease, perioperative chemotherapy regimens given before and after surgery have improved survival, with emerging evidence showing an additional benefit from incorporating immunotherapy.

For patients who cannot receive perioperative chemotherapy, a preoperative chemoradiation approach may help achieve good local control, while definitive chemoradiation can offer a non-surgical option for those who are medically inoperable or decline surgery.

Radiation therapy also plays an important palliative role in relieving gastric cancer-related bleeding, pain and other symptoms, supported by newer techniques that allow for more precise and better-tolerated treatment.

“Management of gastric cancer is complex and multidisciplinary, and the role of radiation therapy has evolved over the past two decades,  requiring thoughtful and dynamic integration with the modalities of surgery, chemotherapy, immunotherapy and palliative care,” said Christopher G.

Willett, MD, FASTRO, chair of the expert panel that developed the guideline and the Mark W.

Dewhirst Professor of Radiation Oncology at Duke University.

“While other societies have published guidelines for treating patients with gastric cancer, this is the first guideline to clarify the role of radiation therapy across all stages of the disease, providing patient-centred, evidence-based recommendations to guide clinical practice,” said Christopher J.

Anker, MD, vice chair of the expert panel and a professor of radiation oncology at the University of Vermont Cancer Centre.

Key recommendations from the guideline are as follows:

Resectable Disease

• Surgery and perioperative chemotherapy (fluorouracil, oxaliplatin and docetaxel (FLOT) given before and after surgery) are recommended for patients with resectable gastric cancer. Pre-surgical radiation therapy with concurrent chemotherapy is recommended for those who are not candidates for perioperative chemotherapy to help achieve negative surgical margins and reduce the risk of early recurrence. Pre-surgical chemoradiation also may be added to perioperative chemotherapy for patients with borderline resectable tumours to improve the chance of removing all the cancer.
• The guideline also addresses the evolving role of immunotherapy as a first-line treatment and the use of chemoradiation therapy after surgery for select patients.

Unresectable (Locally Advanced or Metastatic) Disease

• Definitive radiation therapy with concurrent chemotherapy is recommended for patients with nonmetastatic gastric cancer who decline or are not candidates for surgery. It may be considered for patients with inoperable recurrent gastric cancer if the recurrence is localised or locoregional, and if no prior radiation therapy was given. The guideline also includes a treatment algorithm for managing locally advanced disease.
• For locally advanced or metastatic cancer that cannot be removed surgically, palliative radiation therapy is recommended to provide relief from bleeding, pain, obstruction and other symptoms. Reirradiation also may be considered in the palliative setting for some patients.
• For 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 role of radiation therapy to the primary tumour for patients with stable or regressing metastases to help control symptoms is also reviewed.

Treatment Planning and Delivery

• Recommendations address optimal dosing and fractionation approaches for different stages of gastric cancer and outline suggested treatment volumes to maximise precision and minimise side effects.
• The guideline also discusses best practices for treatment planning and delivery of definitive and palliative radiation therapy, including newer techniques such as intensity modulated radiation therapy, image guidance and respiratory management that can improve treatment tolerance and fidelity
• Care decisions should involve providers from all treating disciplines as well as the patient, with a full discussion of risks and benefits to determine the best treatment approach.

About the Guideline

“Radiation Therapy for Gastric Cancer: An ASTRO Clinical Practice Guideline” was developed by a multidisciplinary panel of radiation, medical and surgical oncologists, a radiation oncology resident, a medical physicist and a patient representative.

Recommendations were based on a systematic review of research published from 2001 through mid-2025.

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), and it is endorsed by ESTRO, SSO, the Royal Australian and New Zealand College of Radiologists and the American Radium Society.

ASTRO's clinical guidelines are intended as tools to promote appropriately individualised, shared decision-making between physicians and patients.

None should be construed as strict or superseding the appropriately informed and considered judgments of individual physicians and patients.

Source: American Society for Radiation Oncology