High relapse rate in patients with MALT lymphoma warrants lifelong follow-up

B-cell lymphoma of the mucosa-associated lymphoid tissue (MALT lymphoma) is thought to be an indolent disease, with a good prognosis following various forms of treatment. Little, however, is known about the rate and pattern of relapse following successful treatment.

We have analyzed time to and pattern of relapse in patients with MALT lymphoma, along with investigation of t(11;18)(q21;q21), t(1;14)(p22;q32), and t(14;18)(q32;q21) involving IGH/MALT1, trisomy 3, and trisomy 18. Eighty-six patients achieving complete remission (CR) after initial therapy with sufficient follow-up data were available. Primary site of disease was the stomach (n = 36), salivary gland (n = 19), ocular adnexa/orbit (n = 12), lung (n = 8), thyroid (n = 5), breast (n = 3), liver (n = 2), and skin (n = 1).

Thirty-two patients (37%) relapsed between 14 and 307 months (median 47 months) after initial CR. Ten relapses were local, whereas the remaining patients relapsed in a distant organ. Eight of 36 gastric versus 24 of 50 nongastric MALT lymphomas (P = 0.02) relapsed. Five patients had a second recurrence 26 to 56 months after a second CR. Relapse rates were not related to forms of initial treatment. Chromosomal aberrations were detected in 14 of 28 (50%) relapsing patients, and chromosomal alterations were identical at diagnosis and relapse. No significant association of any of the genetic changes investigated with relapse was found. Interestingly, patients with t(11;18)(q21;q21) had a significantly longer median time to relapse (76 months) than patients without this translocation (29 months; P = 0.012).

In view of the late relapses seen in our series, lifelong observation of all patients treated for MALT lymphoma seems to be required.