Non-secretory myeloma: a clinician's guide.

The treatment of patients with multiple myeloma has dramatically changed over the past 10 years due to an improved understanding of plasma cell biology and the development of new targets. The subset of these patients with non-secretory myeloma-a group of patients who do not secrete immunoglobulin or its component parts into either the blood or urine-has been challenging to treat and to assess for disease response. Newer methods of assessment for plasma cell disorders, such as the widely used serum free light chain assay, have reduced the number of patients with truly non-secretory myeloma to less than 3% of all newly diagnosed myeloma patients. With regard to prognosis, it appears from most series that patients with non-secretory myeloma have a prognosis similar to or better than that of patients with secretory myeloma.This has not been evaluated in populations from which patients with free light-only disease are excluded, but there is no reason to expect that outcomes in patients with non-secretory myeloma will be appreciably worse, since many harbor the t(11;14) translocation. Finally, imaging with positron emission tomography (PET)/CT scans, and minimal residual disease (MRD) assessment with multi-parameter flow cytometry, may provide newer methods for response assessment, something that has been severely limited in these patients due to the lack of a reliable biomarker. Future directions in response assessment include the amalgamation of imaging and MRD assessment, which may enhance our ability to assess response both in patients with non-secretory myeloma and in other patients with myeloma.