Evaluation of the survival outcomes of multiple myeloma patients according to their plasmacytoma presentation at diagnosis

Objective: Multiple myeloma (MM) associated with extramedullary (EM) plasmacytoma has a poor therapeutic response and poor outcomes when treated with conventional chemotherapy. EM plasmacytoma is divided into two groups: the first group comprises tumors that are extending directly from osteolytic bone lesions (EM-B, bone-related), while the second results from plasmacytoma infiltration into soft tissues with no relationship to the bone (EM-S, soft tissuerelated). This study aimed to compare the general characteristics and survival outcomes of transplant-eligible MM patients who had EM-S or EM-B and MM patients who did not have plasmacytoma at the time of diagnosis. Materials and Methods: This study was performed in a retrospective manner. The MM patients who were treated at our tertiary care center between January 2003 and January 2017 were evaluated retrospectively for the presence of plasmacytoma at diagnosis. Results: There were 141 (78.3%) MM patients who did not have plasmacytoma, 22 (12.2%) MM patients who had EM-B, and 17 (9.4%) MM patients who had EM-S at the time of diagnosis in this study. The 5-year overall survival was 63% in patients who had bone EM-B, 63% in patients who had EM-S, and 80% in patients who did not have plasmacytoma (p=0.02). The 5-year disease-free survival was 47% in patients who had EM-B, 35% in patients who had EM-S, and 54% in MM patients who did not have plasmacytoma (p=0.15). Conclusion: These findings lead us to suggest that MM patients with EM plasmacytoma at the time of diagnosis have poorer prognosis than patients without plasmacytoma, even if autologous stem cell transplantation is performed. The presence of EM involvement negatively affects survival outcomes.