Common community-acquired infections and subsequent risk of multiple myeloma: A population-based study

The role of bacteria and viruses as aetiological agents in the pathogenesis of cancer has been well established for several sites, including a number of haematological malignancies. Less clear is the impact of such exposures on the subsequent development of multiple myeloma (MM). Using the population-based U.S. Surveillance Epidemiology and End Results-Medicare dataset, 15,318 elderly MM and 200,000 controls were identified to investigate the impact of 14 common community-acquired infections and risk of MM. Odds ratios (ORs) and associated 95% confidence intervals (CIs) were adjusted for sex, age and calendar year of selection. The 13-month period prior to diagnosis/selection was excluded. Risk of MM was increased by 5-39% following Medicare claims for eight of the investigated infections. Positive associations were observed for several infections including bronchitis (adjusted OR 1.14, 95% CI 1.09-1.18), sinusitis (OR 1.15, 95% CI 1.10-1.20) pneumonia (OR 1.27, 95% CI 1.21-1.33), herpes zoster (OR 1.39, 95% CI 1.29-1.49) and cystitis (OR 1.09, 95% CI 1.05-1.14). Each of these infections remained significantly elevated following the exclusion of more than 6 years of claims data. Exposure to infectious antigens may therefore play a role in the development of MM. Alternatively, the observed associations may be a manifestation of an underlying immune disturbance present several years prior to MM diagnosis and thereby part of the natural history of disease progression. What's new? Although bacterial and viral infections have been sporadically associated with an increased risk of developing multiple myeloma (MM), a B cell malignancy mostly found in the elderly, the precise role of infectious pathogens in the aetiology of MM remains unclear. In this large population-based study, the authors confirm that the risk of MM is increased by 5-39% following a range of common community-acquired infections, particularly those of the respiratory tract. For a number of infections, a long time interval between infections and diagnosis of MM was observed, reducing the possibility of undetected MM explaining the associations observed. Thus, exposure to infectious agents may promote the malignant transformation of premalignant B cell abnormalities to MM or may reflect a compromised immune system preceding MM diagnosis.