What dose and volume would you treat in a patient with diffuse large B-cell lymphoma confined to the stomach after complete response to R-CHOP?

In a patient with stage IE gastric DLBCL in a complete response (Deauville 1-3) after R-CHOP, I would consolidate with 30 Gy of RT. The volume would depend upon the size of the original tumor and how defined the original disease was on PET-CT and upper endoscopy. In a patient with a smaller lesion in the antrum that appeared well circumscribed at endoscopy, for example, I would feel comfortable treating the original extent of disease with a margin (partial organ irradiation). However, if a lesion was large or poorly circumscribed, then I would favor treating the entire stomach. In this case, I would give 1.5 Gy fractions with prophylactic anti-emetics to limit acute toxicity. For partial stomach irradiation, I usually use 1.8 Gy fractions.