Evaluation of the Impact of the Update SMM Criteria on the Natural History of SMM to Establish New Recommendations.

Inclusion Criteria: * Age ≥ 18 years. * SMM defined by IMWG 2014 criteria 1. Serum monoclonal protein (IgG or IgA) ≥30 g/L and/or urinary monoclonal protein ≥500 mg per 24 h and/or clonal bone marrow plasma cells 10-60% 2. Absence of myeloma defining events or amyloidosis * Diagnosed less than 1 year before the inclusion * Able and willing to give valid written informed consent. Patients must give written informed consent (IC) in accordance with institutional and local guidelines. Exclusion Criteria: * Previous antimyeloma treatment including bisphosphonates * Second Primary Malignancy and/or auto-immune disease treated by immunosuppressive drugs. * Evidence of end organ damage that can be attributed to the underlying SMM: 1. Hypercalcaemia: serum calcium \>0.25 mmol/L (\>10 mg/L) higher than the upper limit of normal or \>2.75 mmol/L (\>110 mg/L) 2. Renal insufficiency: creatinine clearance \<40 mL/min or serum creatinine \>177 μmol/L (\>20 mg/L) 3. Anaemia: haemoglobin value of \>2 g/dL below the lower limit of normal, or a haemoglobin value \<10 g/dL 4. Bone lesions: one or more osteolytic lesions on skeletal radiography, CT, or Positron Emission Tomography-Computed Tomography (PET-CT) * Presence of one of the following biomarkers of malignancy: 1. Clonal bone marrow plasmocytosis ≥60% 2. Involved/uninvolved serum Free Light Chain (FLC) ratio ≥ 100 (The involved free light chain must be ≥100 mg/L) 3. Presence of one or more focal lesions on MRI studies (each focal lesion must be 5 mm or more in size) * History of malignancy other than SMM within 3 years before inclusion * Amyloidosis * POEMS syndrome * Contraindication to MRI * Pregnancy * Nursing mother * Legally protected adults (under judicial protection, guardianship, or supervision)