Multiple Myeloma: What Precedes the Full-Blown Cancer?

Full-blown multiple myeloma is usually preceded by two conditions–MGUS (monoclonal gammopathy of undetermined significance) and smoldering myeloma. MGUS is a condition in which the number of plasma cells in the bone marrow is near healthy amounts, but the same abnormal proteins as multiple myeloma are present throughout the blood, albeit in low amounts. Smoldering myeloma is an intermediate disease between MGUS and full myeloma. Smoldering myeloma contains higher levels of abnormal proteins and plasma cell levels in the bone marrow closer to those of multiple myeloma. Despite these changes, the conditions are symptomless, and they are typically detected during routine blood and urine tests. “They are usually diagnosed by chance because by definition they don’t have any symptoms,” explains Dr. Jens Hillengass, Chief of Myeloma at the Roswell Park Comprehensive Cancer Center.

These conditions do not increase the risk of getting full blown myeloma to a high percentage. MGUS increases the yearly risk to 1%, and smoldering myeloma increases the yearly risk to 10%. Despite this, because of the increased risk of developing myeloma, patients who are diagnosed with one of these two precursor conditions will be monitored closely, explains Dr. Hillengass. “If we know that the patient has those precursor stages, then we actually monitor them to find out if the disease really develops.”