The risk and survival of multiple myeloma as the second primary malignancy in a single Chinese center.

Background: As the overall survival (OS) of patients with multiple myeloma (MM) improves, the incidence of second primary malignancy (SPM) in long-term complications increases. However, there are limited data regarding MM as a SPM. Therefore, this study aimed to determine the time trends in the incidence of MM, as well as the incidence and survival of patients with MM as the SPM. Methods: Kaplan-Meier survival analysis was performed to determine the survival curve, while a log-rank test was used to determine OS. Results: A total of 794 patients were diagnosed with MM among 7,921 patients with hematologic malignancy between 2009 and 2017. The incidence of MM showed an annual upward trend, increasing from 9.3% [2009-2011] to 10.8% [2015-2017]. Of the 794 patients with MM, 16 were diagnosed as the SPM commonly secondary to cancers of the lung (n=4), colon (n=3), breast (n=3), and other (n=6). The median survival of patients with MM as the SPM was 24.5 months (range, 1-95 months). The patients with MM without multiple malignancies had significantly longer survival (median, 46.5 months; range, 17-132 months; P=0.04). Conclusions: This retrospective study suggests that the incidence of MM may be increasing annually and that the survival of patients with MM as the second primary malignant was significantly shorter than that of those without multiple malignancies.