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)