Abstract
We studied 188 patients with a suspected smoldering multiple myeloma (MM) who had undergone a positron emission tomography-computed tomography (PET-CT) scan as part of their clinical evaluation. PET-CT was positive (clinical radiologist interpretation of increased bone uptake and/or evidence of lytic bone destruction) in 74 patients and negative in 114 patients. Of these, 25 patients with a positive PET-CT and 97 patients with a negative PET-CT were observed without therapy and formed the study cohort (n=122). The probability of progression to MM within 2 years was 75% in patients with a positive PET-CT observed without therapy compared with 30% in patients with a negative PET-CT; median time to progression was 21 months versus 60 months, respectively, P=0.0008. Of 25 patients with a positive PET-CT, the probability of progression was 87% at 2 years in those with evidence of underlying osteolysis (n=16) and 61% in patients with abnormal PET-CT uptake but no evidence of osteolysis (n=9). Patients with positive PET-CT and evidence of underlying osteolysis have a high risk of progression to MM within 2 years when observed without therapy. These observations support recent changes to imaging requirements in the International Myeloma Working Group updated diagnostic criteria for MM.
Highlights
Smoldering multiple myeloma (SMM) is an intermediate stage between monoclonal gammopathy of undetermined significance and active MM.[1]
The development of biomarkers to aid in distinguishing these high-risk patients is an area of active interest, and has included assessment of bone marrow plasma cells (BMPC)
MATERIALS AND METHODS We identified all patients with a diagnosis of SMM from January 2000 to March 2014 who had undergone a positron emission tomography-computed tomography (PET-CT) scan as part of their clinical evaluation by using the Mayo Clinic Data Discovery and Query Database and a review of available medical records
Summary
Smoldering multiple myeloma (SMM) is an intermediate stage between monoclonal gammopathy of undetermined significance and active MM.[1]. According to International Myeloma Working Group (IMWG) criteria, the diagnosis of SMM requires clonal bone marrow plasma cells (BMPC) of 10–60% and/ or a serum monoclonal (M) protein 43 g/dl, plus the absence of hypercalcemia, renal failure, anemia and bony lesions (CRAB features) or other myeloma defining events.[3] The current standard of care is observation without therapy until development of symptoms[4]. Treatment as opposed to watchful waiting of patients with highest risk of progression has the potential to improve progression-free and overall survival.[5] The development of biomarkers to aid in distinguishing these high-risk patients is an area of active interest, and has included assessment of BMPC percentage, serum M protein, serum-free light-chain ratio and immunophenotyping of aberrant plasma cells.[2,6,7,8,9,10]
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