- Multiple myeloma is a type of cancer that affects white blood cells and has a poor long-term survival rate. Two other types of cancer, monoclonal gammopathy of undetermined significance (MGUS) and smoldering myeloma (SMM), may eventually progress and develop into multiple myeloma. Researchers are interested in collecting samples from individuals who have been diagnosed with MGUS and SMM to study possible risk factors for developing multiple myeloma.