Risk of skin cancer in multiple myeloma patients: a retrospective cohort study.

Immunosuppressed patients are known to have an increased incidence of skin cancer. Patients with multiple myeloma (MM) show impaired immune function. In the past, because of poor survival, the incidence of specific secondary primary malignancies such as skin cancer among these patients was difficult to establish. With more effective MM therapies that have emerged in recent years, these patients are living markedly longer, and therefore, it becomes of increasing importance to determine whether their risk of developing other medical problems such as skin cancer is increased. We performed a retrospective cohort study of 205 myeloma patients and 193 age-, race-, and gender-matched control subjects to assess the incidence of skin cancers among patients with MM and determine the specific types of and risk factors for skin cancer. We found that there is an increased occurrence of skin cancer among patients with MM compared to control subjects (26.8% vs. 16.1% in controls; P = 0.009). Among specific types of skin cancer, the proportion of patients with squamous cell carcinoma (SCC) was higher than controls (P = 0.016). In addition to MM diagnosis, older age and Caucasian ethnicity were predictors of skin cancer of any type. Furthermore, older age was also a predictor of SCC.