Multiple myeloma and frequency of synchronous and second primary malignancies

Malignancies accompanying multiple myeloma (MM) can be observed at diagnosis or during the course of the disease. Several trials have investigated the type, frequency, and effects of these malignancies on the overall survival of MM patients. Here, we aimed to investigate the frequency and types of previous/synchronous and second primary malignancies, median duration to develop a second primary malignancy during the course, and the effect of these malignancies on overall survival in our MM patients. Three hundred ten symptomatic MM patients were included and analyzed retrospectively. Malignancies detected before or after MM diagnosis were recorded. The SPSS 26.0 (NY, USA) software program was used for the statistical analysis, and a p-value below 0.05 was considered significant. Eight (2.5%) and 5 patients (1.6%) had previously/synchronous and second primary malignancies, respectively. Chronic lymphocytic leukemia, prostate cancer, primary breast cancer, metastatic breast cancer, and endometrial cancer were the most common previous or synchronized malignancies (0.3%, 1%, 0.6%, 0.3%, and 0.3%, respectively). During the follow-up, stomach, larynx, lung, and colon cancers were reported at rates of 0.6%, 0.3%, 0.3%, and 0.3%, respectively. The median time to develop a second malignancy was 17.2 months. Patients with a second malignancy had shorter overall survival than patients without malignancy (29 +/- 3.9 versus 67 +/- 4.9 months, p: 0.038). Although existing studies conflict with each other in some points due to their design, our study detected a 2.5% of secondary malignancy occurrence rate with a significantly decreased survival.