Long term follow up of monoclonal gammopathy of undetermined significance (MGUS) in US Veterans: Racial differences and associations with other malignancies.

Abstract

7573 Background: Monoclonal gammopathy of undetermined significance (MGUS) is associated with lymphoid malignancies such as lymphoma and myeloma, but the association with other malignancies has not been described in the US veteran population. Methods: Veterans diagnosed with MGUS from 1991-2023 were identified from the US Veteran Affairs Central Cancer Registry (VACCR). Age at the diagnosis of MGUS was divided into four categories of <60, 60-69, 70-79, 80+. Variables collected included demographic factors and the diagnosis of other cancers. Differences were analyzed using the Chi Square test. Results: There were 3975 veterans who met the criteria. Most patients were male (96.7%) with a median age at diagnosis of MGUS of 70.5 (IQR 65.4-76.0). Almost 1/3 of patients were Black and were diagnosed with MGUS at a younger age compared to White veterans (Table, p<0.0001). Over the 32-year period included in this study, 2/3 of patients remained with a diagnosis of MGUS (62.3%) alone whereas 29.4% had 1 additional malignancy diagnosed and 8.3% had 2 or more additional malignancies. Black veterans with MGUS were more likely to have additional malignancies than white patients (41.4% vs 35.9%, p=0.016). MGUS was diagnosed prior to other cancers in 52% of patients and afterward in 48%. The most common cancers diagnosed in patients with MGUS were prostate (31%), lymphomas (13%), GI (12.5%), lung (12.0%), and skin (6.8%). CLL (3.4%), LPL (3.0%). Among lymphomas, CLL (3.4%) and LPL (3.0%) were most common. Of note, multiple myeloma or plasmacytoma was diagnosed in 6.5% of patients. The proportion of patients with MGUS and additional malignancies was comparable in the 4 age cohorts (p=0.072), indicating that younger patients with MGUS were as likely to be diagnosed with additional malignancies as older patients. Conclusions: In US veterans, nearly 1/3 of those diagnosed with MGUS were Black. These patients were younger when diagnosed with MGUS and were more likely to develop additional malignancies compared to White veterans. Over the 32 years of this study, a considerable proportion of veterans with MGUS developed various solid tumors. Further investigation is warranted to understand the racial, genetic, and other factors that may be contributing to the development of cancers in patients with MGUS. [Table: see text]