Risk of multiple myeloma and other malignancies among first- and second-degree relatives of patients with multiple myeloma: A population-based study.

OBJECTIVES: We conducted a population-based study to assess the risk for multiple myeloma (MM) and other cancers in first- and second-degree relatives of MM patients, and to investigate whether evidence of anticipation is present in familial MM. METHODS: We retrieved 24 845 first-degree relatives and 41 008 second-degree relatives of 7847 MM patients, and 86 984 first-degree relatives, and 138 660 second-degree relatives of 26 511 matched controls. A Cox model was used to assess the risk for MM and other cancers in relatives of MM patients. Anticipation was assessed by a Cox model, where all parents and offspring of MM patients were included in the risk set. RESULTS: In second-degree relatives of MM patients, no overall significant association with an MM diagnosis was observed (HR 1.99; 95%CI:0.86-4.57). In parents and offspring of MM patients, we found no significant difference in the ages at onset of MM (HR 1.28;95% CI:0.50-3.28). In affected parent-offspring pairs, we observed no statistically significant difference in overall survival between the generations (HR 0.74; 95%CI:0.20-2.69). CONCLUSIONS: Overall, second-degree relatives of MM patients were not associated with an increased risk for MM. Our study supports that genetic anticipation is not present in familial MM.