Association Between Synchronous Occurrence of Multiple Myeloma and Carcinoma Prostate: Literature Analysis in the Context of a Case Report.

Carcinoma of the prostate is the second most common cancer in males, while multiple myeloma is the 17th most common cancer. The synchronous diagnosis of multiple myeloma and carcinoma of the prostate is a sporadic phenomenon with scarce published literature and a diagnostic and therapeutic dilemma. Here, we present a case of synchronous diagnosis of IgG and lambda subtypes of multiple myeloma with multiple lytic lesions, the revised international staging system (R-ISS 2), and non-metastatic acinar adenocarcinoma prostate, a very high-risk category. The patient received 25 weekly doses of cyclophosphamide, bortezomib, and dexamethasone (CyBorD)-based chemotherapy for myeloma and androgen deprivation therapy with injection leuprolide for prostate cancer. After reasonable disease control, the patient underwent an autologous stem cell transplant for multiple myeloma with melphalan at 140 mg/m2 and was offered definitive radiation therapy for prostate cancer. The potential association between carcinoma of the prostate and multiple myeloma has been hypothesized because of similarities in the tumor microenvironment. There are possible common biological pathways leading to co-stimulatory mechanisms, like interleukin-2 (IL-2), insulin-like growth factor 1 (IGF-1), stromal cell-derived factor 1 (SDF-1), and vascular endothelial growth factor (VEGF). However, they are not proven and warrant further research. This case highlights key areas of diagnosis and management of this sporadic occurrence, along with literature analysis and the need for further research, and is likely to be beneficial for clinicians in decision-making in future cases.