Risk factors for progression in smoldering multiple myeloma

This paper studied the risk factors of progression in smoldering myeloma. Reduced immunoglobulin and high levels of plasma cells were found to increase the risk of progression. 

Multiple myeloma is a cancer of the plasma cells (type of white blood cell). Smoldering multiple myeloma is a precancerous form of myeloma. In smoldering myeloma, there is the presence of abnormal monoclonal protein in the blood or urine, with no symptoms or damage to major organs. Smoldering myeloma can progress to multiple myeloma.

Current studies have found that reduced immunoglobulins (molecules produced by plasma cells), abnormally high levels of plasma cells and abnormal levels of free light chain (molecule produced by plasma cell) increases the risk of progressing from smoldering myeloma to multiple myeloma. However, there is currently no consensus on how to classify low, intermediate, or high-risk smoldering multiple myeloma.  

321 patients with smoldering multiple myeloma were analyzed. 209 patients underwent free light chain analysis. 216 patients had their levels of immunoglobulin measured. 61 patients progressed to multiple myeloma with an average follow-up period of 729 days.

A high bone marrow plasma cell level was a significant risk factor for progression to multiple myeloma. A high free light chain ratio did not significantly increase the risk of progression. High levels of monoclonal protein (30g/L or more) at diagnosis was associated with a 2.7 times increased risk of time to progression. Presence of reduced immunoglobulin also increased the risk of time to progression by 3.3 times.

Using the risk factors identified (reduced immunoglobulin levels and monoclonal protein of 30 g/L or more), a scoring system was created to identify low-, intermediate-, and high-risk patients. Patients with no risk factors were classified low risk and had a 5% risk of progression at 2 years. Patients with 1 risk factor were classified as intermediate risk with 18% risk of progression at 2 years. Patients with 2 risk factors were high risk with 38% risk of progression at 2 years. 

The authors concluded that a monoclonal protein level of 30 g/L or more and reduced levels of immunoglobulin remain important risk factors for progression to multiple myeloma.