Characterization of Second Primary Malignancies in Mucosa-Associated Lymphoid Tissue Lymphomas: A SEER Database Interrogation

We evaluated second primary malignancies (SPMs) among patients with mucosa-associated lymphoid tissue (MALT) lymphomas using the SEER-18 database. During this time, a total of 12,500 cases of MALT lymphoma were diagnosed of which 1466 patients developed 1626 SPMs. These findings indicate that while MALT lymphomas have an indolent biology, there is nevertheless an increased risk for SPMs, which support the need for long-term follow up during survivorship in order to identify SPMs. Introduction: : Second primary malignancies (SPMs) are long-term complications in cancer survivors. Mucosa-associated lymphoid tissue (MALT) lymphomas are indolent extra-nodal marginal zone lymphomas, the majority of which typically have long-term survival. In this study, we investigated the incidence and pattern of SPMs in adult patients diagnosed with MALT lymphomas between January 2000 and December 2016. Methods: : Using the SEER-18 database and multiple primary standardized incidence ratio (MP-SIR) session of SEER stat software for statistical analysis, we assessed SPMs in MALT lymphomas. Results: : During this time, a total of 12,500 cases of MALT lymphomas were diagnosed, of which 1466 patients developed 1626 SPMs (O/E ratio: 1.48, 95% CI:1.41-1.55, P <.001). The median latency period for development of SPMs was 54 months (range 6-201 months). Secondary non-Hodgkin lymphomas, as defined by SEER as distinct from the primary lymphoma, was the most common SPM with 299 cases, followed by lung cancer (O/E ratio: 6.15, 95% CI:5.47-6.89, P <.0001). There were 898 SPMs that developed between 6- 59 months (O/E ratio: 1.47, 95% CI:1.37-1.57, P <.0001) and 728 after 60 months latency (O/E ratio: 1.5, 95% CI:1.39-1.61, P <.0001) after diagnosis of the primary MALT lymphomas. An increased incidence of both solid and hematologic cancers occurred in patients as early as 6 months after diagnosis of MALT lymphoma. Conclusion: : These findings indicate that despite the indolent nature of most MALT lymphomas, there is an increased risk for SPMs warranting long-term follow up. (C) 2021 Elsevier Inc. All rights reserved.