Gastric MALT Lymphoma: A Partial Response That May Be a Red Herring
A partial response at four months after H. pylori eradication is either a lymphoma still on its way out or a lymphoma that was never going to leave. A single translocation result separates those two readings — and it was run on tissue taken before treatment started.
Y.T., a 51-year-old high school guidance counselor, was diagnosed with stage IE gastric MALT lymphoma after an endoscopy for persistent dyspepsia found a thickened area of gastric mucosa, biopsied and confirmed H. pylori-positive. She completed a standard course of eradication therapy, and the organism is confirmed cleared — which matters, because it removes the commonest explanation for a disappointing restaging and leaves only the lymphoma to account for it. Her repeat endoscopy at four months showed a reduced but still-present lymphoid infiltrate: a partial histologic response, not the full regression eradication alone produces in most early-stage, H. pylori-positive disease. She remains stage IE, no nodal or distant involvement, which keeps every option on the table and is also why the decision is difficult rather than forced.
A partial response at four months is, on its own, not unusual — real, well-documented cases of gastric MALT lymphoma continue slowly regressing for up to a year or more after successful eradication, and repeat endoscopy showing residual disease at this point doesn't automatically mean the treatment has failed. What complicates that reassurance is a result that came back on the same biopsy specimen: a t(11;18) API2-MALT1 translocation — the marker Liu and colleagues identified as predicting which gastric MALT lymphomas will not respond to H. pylori eradication at any stage. The two readings of her endoscopy are therefore not degrees of the same thing. Either she is a slow responder, in which case more time is the treatment and radiation would be an over-reaction to a normal trajectory; or she carries a marker that says the response she has is the response she gets, in which case the months spent waiting are months of a lymphoma sitting undisturbed in her stomach. The translocation result is what separates those readings, and it was run on tissue taken before any of this started.
GI-oncology conference, restaging review
A partial response at four months is within the expected timeline — real cases of eradication-responsive gastric MALT lymphoma keep regressing slowly for up to a year or more after successful treatment. I'd continue watchful waiting with repeat endoscopy rather than call this a failure this early.
I'd weigh the translocation as changing what that partial response actually means. Liu's series established t(11;18) as a marker for gastric MALT lymphomas that will not respond to eradication — not slower responders, non-responders. If it's genuinely present, her residual infiltrate isn't early progress toward full regression; it's a disease that was never going to clear on eradication alone however long we give it.
The expected-timeline argument assumes her biology matches the cases that timeline was built from — the translocation result is specifically evidence that hers may not.
Before either of you finalizes a plan on the strength of a single translocation result, I'd want it confirmed on her current tissue. Translocation status is occasionally discordant between an original diagnostic sample and a post-treatment biopsy, and given how much weight this single molecular finding is carrying in the decision, that's worth ruling out before committing her to radiation therapy.
Agreed: confirm the translocation on current tissue first; if confirmed, proceed to involved-site radiation therapy rather than continuing to wait for a spontaneous full response the biology makes unlikely.
What the translocation result answers for him, it doesn't answer in general: a timeline-based approach to watchful waiting still has nothing to say about when a partial response is genuinely still resolving versus already a sign the biology won't cooperate — it only worked here because a specific molecular test happened to exist and happened to come back positive. A patient without that same testing option, or with a negative one, would leave this exact disagreement unresolved.