Objective: The global incidence of obesity has risen dramatically in recent decades, with consequent detrimental health effects. Extensive studies have demonstrated that obesity significantly affects the risk, prognosis, and progression of various cancers, including multiple myeloma (MM). As an established modifiable risk factor for both MM and its precursor stages -monoclonal gammopathy of unknown significance (MGUS) and smoldering MM (SMM)- the association between obesity and disease onset has become a compelling area of research. This review presents a comprehensive overview of the current epidemiological evidence linking obesity to MM, emphasizing its role in disease pathogenesis and patient outcomes. It also offers insights into the molecular mechanisms underlying this deleterious association, and discusses therapeutic strategies targeting obesity-driven contributions to MM.

Results: Emerging epidemiological evidence suggests that obesity not only influences MM development but also alters its biological behavior, impacting myelomagenesis, and clinical outcomes. Biologically, multiple pathways exist through which adipose tissue may drive MM onset and progression. Obesity fosters a state of chronic inflammation, where dysfunctional adipocytes and fat-infiltrating immune cells release proinflammatory cytokines, growth factors, adipokines, and fatty acids, contributing to the proliferation and expansion of MM. Additionally, communications between MM cells and adipocytes within the bone marrow are crucial in MM biology. Collectively, the discoveries described in this review underscore the necessity for broader preclinical and clinical investigations to better characterize the complex interplay between obesity and MM, and to determine whether lifestyle interventions can impact MM incidence and clinical outcomes, particularly in high-risk populations.