Association of thyroid disease and thyroid autoimmunity with multiple myeloma risk: a case-control study

Thyroid disease has been associated with lymphohematopoietic cancer (LHC). No previous study using clinical, sonographic and laboratory data has explored whether thyroid disease and specifically autoimmune thyroid disease (ATD) is associated with multiple myeloma (MM) risk. 73 patients with incident primary MM and 73 hospital controls admitted for non-neoplastic and non-infectious conditions, matched on gender and age were studied between 2001 and 2007. Blood samples were collected. All subjects were submitted to clinical, ultrasound and laboratory thyroid evaluation. The prevalence of clinical thyroid disease in MM patients was significantly higher than in controls (p = 0.002). ATD was associated with increased risk of MM, adjusting for age, gender, body mass index and familial history of LHC [OR = 5.68, 95% confidence interval (CI): 1.69-19.13]. Controlling for the above variables, an individual suffering from any thyroid disease more than 10 years has about 2.41 times more likely the risk to develop MM than an individual without any thyroid disease (OR = 2.41, 95% CI: 1.35-4.29). Also, adjusting for age, gender, BMI and family history of LHC, a familial history of thyroid disease is associated with increased risk of MM (OR = 3.23, 95% CI: 1.25-8.31). Further studies are needed to explore underlying mechanisms associating thyroid autoimmunity with plasma cell transformation.