ISRT 20 Gy for Indolent Localized Gastrointestinal (GI)-Lymphoma

This study tests a moderate dose of radiation (20 Gy) delivered to the area involved by lymphoma in patients with slow-growing stomach or duodenal lymphoma. The goal is to treat the lymphoma effectively while minimizing radiation side effects compared to higher doses. **You may be eligible if...** - You are 18 or older - You have been diagnosed with an indolent (slow-growing) gastric or duodenal lymphoma — specifically marginal zone lymphoma (MZL) or follicular lymphoma (FL) - Your lymphoma is at an early stage (Stage I or II) - Your H. pylori (stomach bacteria) infection has been treated and the lymphoma has not responded, or you tested negative for H. pylori **You may NOT be eligible if...** - You have had prior radiation to the gastrointestinal area - Your lymphoma is at an advanced stage (Stage III or IV) - You have HIV, active Hepatitis B or C, or inflammatory bowel disease - You are pregnant or breastfeeding - You have had another cancer in the past 3 years (with some exceptions) Talk to your doctor to see if this trial is right for you.