Edited excerpt from the discussion:

DR HAINSWORTH: We have moved away from routine surgery for gastrointestinal lymphomas, particularly for gastric lymphomas with which we have a fair amount of experience with chemotherapy. Although no randomized trials are perfect, several large series have had similar results. The initial concern about chemotherapy and gastric perforations has not proven to be a common complication; therefore, that concern has decreased in importance in people’s minds when considering initial treatment.

DR CABANILLAS: We have to be careful interpreting the data on the use of antibiotics in these cases. If you evaluate the patients with gastric lymphoma who have large cell lymphoma and MALToma, frequently the area of large cell lymphoma might be small, and the predominant tumor bulk might be low grade MALToma.

If you treat these patients with antibiotics, the tumors may shrink but you might miss an area of residual large cell lymphoma because the endoscopies are not always able to identify it.

Anecdotal data in the literature show that the antibiotics don’t work when the tumor transforms into large cell lymphoma. One of the mistakes an inexperienced gastroenterologist can make when they stage these patients is obtaining only one biopsy because they might miss an area of large cell lymphoma; therefore, it is always important to obtain multiple biopsies.

I had a patient whom I managed in consultation, who had been diagnosed with MALToma, treated with antibiotics and had a response, but also had a residual tumor mass. A repeat biopsy revealed evidence of large cell lymphoma that had not been diagnosed initially, so it can be tricky.

Most patients, who have a large tumor mass, even if it’s low grade MALToma, do not respond to antibiotics. The ones who respond well to antibiotics are those with a superficial gastritis type of presentation. Years ago, we published data in the Annals of Internal Medicine, which showed that patients who have large tumor masses or large ulcerations and have endoscopic appearance of transmural disease don’t respond to antibiotics the majority of the time. I believe that approximately one third of the patients respond, but the majority of patients do not.

Even if a patient did not have large cell lymphoma — just a large tumor mass and low grade lymphoma — eventually that patient will likely require more treatment than antibiotics. It is good to start with antibiotics to treat the Helicobacter pylori and prevent the induction of some other malignancy, including gastric cancer; however, most patients will eventually require radiation.

DR C FARBER: I can tell you anecdotally that I have seen three such patients. I presented the case of one that did not respond to the anti-H pylori treatment; however, in my experience, one out of the three had full regression of the lymphoma, including the large cell component. I’m one for three, whereas the literature suggests 10 out of 15.

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