Low-Dose Irradiation Allays 93% of Gastric MALT Lymphomas at 10 Years



LONDON – Low-dose irradiation of the stomach in patients with gastric MALT lymphoma absent or independent of infection by Helicobacter pylori is associated with a 93% disease control rate after 10 years.

As presented by Dr. Joachim Yahalom, a radiation oncologist at Memorial Sloan-Kettering Cancer Center in New York, these long-term study findings highlight the high disease-control rates that can be obtained using low-dose involved field radiotherapy (IFRT).

Low-dose IFRT has now become a standard of care in the United States, although approaches still vary in Europe, he reported May 9 at the European Society for Therapeutic Radiation Oncology Anniversary Conference.

Indeed, the latest guidelines set by the National Comprehensive Cancer Network on non-Hodgkin’s lymphomas – which includes gastric MALT (mucosa-associated lymphoid tissue) lymphoma of the stomach – recommend the use of radiotherapy as a first-line option when patients have early (stage I/II) H. pylori–negative disease.

"We started using this [low-dose irradiation] treatment approach in the early 90s. Until then, the standard treatment for this lymphoma in the stomach was total gastrectomy, and sometimes it was followed by radiation therapy," said Dr. Yahalom, a professor of radiation oncology at Cornell University in New York. He added that chemotherapy and rituximab (Rituxan) were not generally very effective.

"Obviously the treatment of choice is to give antibiotics if H. pylori is present," Dr. Yahalom added, noting that substantial regression of MALT lymphoma can occur via treatment with antibiotics that target the gastric bacterium in positive cases. However, when H. pylori is not present, or if there is a lack of response to or residual lymphoma after complete response to antibiotic therapy, then radiotherapy is the recommended next step.

Dr. Yahalom presented data representing 16 years of experience in treating 103 patients (60 women and 43 men) with gastric MALT lymphoma in 1992-2009. The majority of patients (76%) had stage I disease, with 19% having stage II, and fewer than 5% having stage IV.

The median age of the patients was 62 years (range, 25-91 years). Symptoms were relatively mild at presentation, Dr. Yahalom observed: In all, 52% had epigastric pain, 36% had nausea, 29% had gastric bleeding, 18% had anorexia, 15% had anemia, and 10% had unknown or no obvious symptoms.

Almost two-thirds of patients were H. pylori negative. This included four patients who had relapsed after a complete response to antibiotic therapy. A further 20% of patients had persistent lymphoma after H. pylori eradication therapy. Another 15% had H. pylori and lymphoma remaining after antibiotic treatment, but had progressive symptoms or disease that could not wait for another antibiotics trial.

Prior to being treated with IFRT, six patients had undergone surgery, and seven had received medications that failed to control their disease.

Approximately 90% of patients were given IFRT at a median dose of 30 Gy in 1.5 Gy fractions for 4 weeks. The lowest and highest total radiation doses administered were 22.5 Gy and 43.5 Gy.

Patients received regular follow up via endoscopic biopsies, and after a median of 5.5 years, the disease control rate was 98%. One-fifth of patients had been followed for 10 years, and the 10-year freedom from local failure was 93%; the 10-year overall survival rate was 74%.

There were no significant acute or late adverse events, Dr. Yahalom noted, and just eight patients relapsed (six with gastric MALT lymphoma and two with diffuse large B-cell lymphoma). Subsequent other cancers included lymphoma in extragastric sites (eight patients), adenocarcinoma of the stomach (two), and second tumors close to the radiotherapy field (one in the colon and two in the pancreas). "Other deaths appeared unrelated to disease or treatment," he said.

Based on this experience, Dr. Yahalom concluded that "low-dose irradiation of the stomach provides excellent long-term disease control [and] is safe and simple.

"Radiation therapy, in our opinion, is the treatment of choice for patients with MALT lymphoma that have exhausted their antibiotic options or are unlikely to respond to it."

Dr. Yahalom said he had no financial conflicts of interest.

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