Patterns of previous and secondary malignancies in patients with multiple myeloma

Objectives In contrast to secondary primary malignancies (SPM) following multiple myeloma (MM), less is known about previous malignancies. We therefore conducted a population‐based study to assess the patterns of previous malignancies in MM patients as well as the risk for SPM. Methods Using data from the Cancer Registry of Norway, we included 9574 MM patients and 37 810 matched control subjects. The association between previous malignancies and a subsequent diagnosis of MM was analysed by a logistic regression model and the risk for SPM by a Cox model. Results A previous diagnosis of myeloproliferative neoplasia (MPN) (OR 3.57; 95% CI:1.45‐8.80) and Hodgkin lymphoma (HL) (OR 3.66; 95% CI: 1.40‐9.55) was associated with the subsequent development of MM. For MPN, the association with MM was explained by an excess of primary myelofibrosis (PMF) in the MM group. The overall incidence of a previous malignancy was not different between MM patients and the control subjects (OR 0.93; 95% CI: 0.87‐1.00). MM patients had an increased risk for secondary acute myelogenous leukaemia/myelodysplastic syndromes (HR 6.1, 95% CI: 3.9‐9.5). Conclusions A previous diagnosis of HL and PMF was associated with a subsequent diagnosis of MM, whereas the overall incidence of previous cancers was not increased for MM patients.