Gastric cancer is often diagnosed in the later stages because early signs and symptoms of the disease are subtle. The primary treatment is surgical resection of the tumor. Chemotherapy, targeted/immunotherapy, and radiation therapy also play a role in the treatment of gastric cancers. Radiation therapy (RT) is typically used for tumors that cannot be resected surgically or in patients who are not well enough to undergo surgery. Radiation therapy is also used for patients with metastatic disease and for palliative care of patients with gastric cancers.
In today's guideline side-by-side comparison, we look at the latest clinical practice guidelines from the American Society for Radiation Oncology (ASTRO) and the National Comprehensive Cancer Network (NCCN) on postoperative radiation therapy for gastric cancer.
Guideline for Comparison
| Item | Radiation Therapy for Gastric Cancer: An ASTRO Clinical Practice Guideline | NCCN Guidelines Version 2.2026 Gastric Cancer |
|---|---|---|
| Authoring Organization | American Society for Radiation Oncology | National Comprehensive Cancer Network |
| Publication Date | November 2025 | January 2026 |
| Graded Recommendations | Yes | Yes |
| Links | Summary / Full Text | Full Text |
Key Takeaways
Indications for Radiation Therapy
- Both ASTRO and NCCN recommend chemoradiation for patients with locoregional gastric cancer that is unresectable and for those who decline surgery.
- For patients with recurrent locoregional gastric cancer, ASTRO recommends curative treatment with chemoradiation for unresectable tumors, but NCCN recommends chemoradiation as part of palliative management for these patients.
- For patients with metastatic disease ASTRO conditionally recommends radiation therapy to the primary tumor and NCCN recommends palliative management with chemoradiation.
- Both ASTRO and NCCN recommend radiation therapy for palliation of pain, gastrointestinal bleeding, and gastric obstruction.
Postoperative Chemoradiation
- Both ASTRO and NCCN consider using fluoropyrimidine-based chemoradiation after gastric tumor resection and lymphadenectomy with less than a D2 dissection.
Radiation Planning and Guidance
- Both societies recommend chemoradiation planning with intensity-modulated radiation therapy (IMRT) or 3-dimensional conformal radiation therapy (3-D-CRT).
- Both societies recommend 4-dimensional CT to plan treatment when organ or respiratory motion management is likely to be needed.
- ASTRO prefers 3-D CRT or IMRT over 2-D imaging for planning clinical target volumes for patients receiving palliative care radiation therapy.
Radiation Coverage
- Both ASTRO and NCCN recommend postoperative radiation include the tumor bed, anastomoses, and regional lymph nodes.
- ASTRO recommends coverage of the gastric remnant only for patients with positive margins and NCCN recommends considering the risk versus benefit of gastric remnant coverage.
Dose Fractionation/Target Volumes
- NCCN recommends 4500 to 5040 cGy in 25 to 28 fractions with higher doses considered for positive surgical margins as a boost.
- ASTRO makes target volume and dose fractionation recommendations based on whether the disease is metastatic, resectable, initial diagnosis, recurrent diagnosis, and whether the treatment is curative or palliative in nature. Treatment for curative intent is very similar to NCCNs recommendation between 4500 and 5040 cGy in 25 to 28 fractions.
- Nonmetastatic, resectable/resected, initial diagnosis: 4500 cGy in 25 fractions.
- Nonmetastatic, unresectable or decline surgery, initial diagnosis: 4500 to 5040 cGy in 25 to 28 fractions.
- Nonmetastatic, locoregional recurrent, RT naive: 4500 to 5040 cGy in 25 to 28 fractions.
- NCCN also gives target volume and fractionation dose recommendations for palliative treatment which ASTRO does not address.
Side-by-Side Comparison of Recommendations
| Type | ASTRO | NCCN |
|---|---|---|
| Indications for RT (Locoregional Disease) | Nonmetastatic, initial diagnosis, curative intent: For patients with nonmetastatic gastric cancer who are not candidates for surgery or decline surgery, chemoradiation with or without induction and/or consolidation systemic therapy is recommended. Nonmetastatic, recurrent, curative intent: For RT-naïve patients with nonmetastatic and locoregional recurrent gastric cancer after gastrectomy, definitive chemoradiation with or without induction and/or consolidation systemic therapy is conditionally recommended if the tumor is medically inoperable or unresectable. | Chemoradiation may be considered for patients with locoregional disease who have surgically unresectable tumors. Palliative care with chemoradiation may be considered for patients with locoregional disease who are not candidates for surgery. |
| Indications for RT (Metastatic Disease) | For patients with metastatic gastric cancer and controlled systemic burden, RT to the primary tumor is conditionally recommended. | Palliative management using chemoradiation may be considered for patients with metastatic disease. |
| Indications for RT (Palliative Management) | For patients with gastric cancer-associated bleeding and/or pain from the primary tumor, palliative RT is recommended. For patients with gastric cancer-associated obstruction from the primary tumor, palliative RT is conditionally recommended. For patients with gastric cancer who received prior RT, reirradiation is conditionally recommended for palliation of gastric bleeding. | External beam RT may be used to help manage tumor-related pain. External beam RT may be used to help manage gastric obstruction. External beam RT may be used to manage acute and chronic gastrointestinal bleeding. |
| Postoperative Chemoradiation | For patients with pT1N2-3, pT2N+, and/or pT3-4 any N stage resected gastric cancer who are not candidates for perioperative or postoperative multiagent chemotherapy, postoperative chemoradiation (with concurrent 5-FU or capecitabine) is conditionally recommended. For patients with pT1N2-3, pT2N+, and/or pT3-4 any N stage resected gastric cancer who have < D2 lymphadenectomy, postoperative chemoradiation (with concurrent 5-FU or capecitabine) with or without postoperative chemotherapy is conditionally recommended. For patients with cT2-4 and/or N+ resected gastric cancer with R1-2 resection, postoperative chemoradiation (with concurrent 5-FU or capecitabine) with or without postoperative chemotherapy is conditionally recommended, whether or not preoperative systemic therapy was given. | After R0 resection of tumors classified as deep pT1bbb or pT2, N0: fluoropyrimidine then fluoropyrimidine-based chemoradiation then fluoropyrimidine for certain patients. After R0 resection of tumors classified as pT3, pT4, any N, or any pT, N+ with less than a D2 dissection: fluoropyrimidine then fluoropyrimidine-based chemoradiation, then fluoropyrimidine. After R1 resection: fluoropyrimidine-based chemoradiation. After R2 resection: fluoropyrimidine-based chemoradiation or palliative management. |
| Radiation Planning / Guidance | For patients with nonmetastatic gastric cancer receiving preoperative or postoperative chemoradiation, IMRT (including VMAT) or 3-D CRT is recommended. Implementation remark: If using IMRT (including VMAT), 4-D CT planning and/or respiratory motion management techniques with daily image guidance are appropriate. For patients with gastric cancer receiving palliative RT, limiting the treatment volume to the gross tumor volume (GTV) with a margin for planning target volume (PTV) is conditionally recommended. Implementation remarks: If the extent of the GTV is not discernible, include the whole stomach as the clinical target volume (CTV) with a margin for PTV. 3-D CRT or IMRT (including VMAT) planning is preferred over 2-D planning. | Treatment planning should use three-dimensional conformal radiation therapy (3-D-CRT) or intensity-modulated radiation therapy (IMRT). Four-dimensional CT planning and/or organ or respiratory motion management may be used when needed. |
| Radiation Coverage | For patients with nonmetastatic gastric cancer receiving postoperative chemoradiation, inclusion of the tumor bed, anastomoses, and regional nodes is recommended. For patients with nonmetastatic gastric cancer receiving postoperative chemoradiation, inclusion of the gastric remnant is conditionally recommended for positive margins only. | Chemoradiation should take into consideration tumor location and margin and should include tumor bed, anastomoses, stumps, and nodal areas at risk. Gastric remnant chemoradiation should take into consideration the risk versus benefit of treatment. |
| Dose Fractionation / Target Volumes | Nonmetastatic, resectable/resected, initial diagnosis, curative intent: For patients with nonmetastatic gastric cancer receiving preoperative or postoperative chemoradiation (with concurrent 5-FU or capecitabine), 4500 cGy in 25 fractions is recommended. Nonmetastatic, initial diagnosis, definitive RT with curative intent: For patients with nonmetastatic gastric cancer who are medically inoperable, have unresectable disease, or decline surgery, definitive chemoradiation using a dose of 4500-5040 cGy in 25-28 fractions is conditionally recommended. Nonmetastatic, locoregionally recurrent, definitive RT with curative intent: For patients with RT-naïve, nonmetastatic, locoregionally recurrent gastric cancer after gastrectomy, chemoradiation with an RT dose of 4500-5040 cGy in 25-28 fractions is conditionally recommended if the tumor is medically inoperable or unresectable. Symptomatic, palliative intent: For patients with gastric cancer receiving palliative RT for symptoms related to the primary tumor, regimens of 1-10 fractions with a BED range of 1440-3900 cGy10 (eg, 800 cGy in 1 fraction, 2000 cGy in 5 fractions, or 3000 cGy in 10 fractions) are recommended. For patients with gastric cancer, reirradiation regimens of 1-10 fractions with a biologically effective dose (BED) range of 1440-2800 cGy10 (eg, 800 cGy in 1 fraction, 1500 cGy in 5 fractions, or 2000 cGy in 10 fractions) are conditionally recommended for palliation of gastric bleeding. | General postoperative dosing: 45-50.4 Gy (1.8 Gy/day) (total 25-28 fractions) Higher doses may be considered as a boost in certain patients with positive surgical margins. |
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