Spinal metastases in multiple myeloma: A high-risk subgroup for ISS III patients.

BACKGROUND: Patients with multiple myeloma (MM) have an extremely heterogeneous prognosis. The International Staging System (ISS) is actually the most reliable staging system and chromosomal abnormalities were integrated in the Revised-ISS. We wanted to evaluate the prognostic value of spinal secondary localization in patients with MM and its impact on the ISS.

METHODS: Epidemiological and biological data, as well as treatment protocols and secondary localization were analyzed for 650 consecutive patients diagnosed with MM from January 2006 to January 2017.

RESULTS: The overall survival (OS) was dependent on the WHO performance status, ISS and Salmon and Durie stage at diagnosis. Furthermore, presence of spinal metastases at diagnosis was predictive of a worse outcome (p < 0.0001), while presence of peripheral bone metastases was not. Spinal metastases had a significant impact on OS for ISS III patients (p < 0.0001). Also, a history of bone marrow graft was associated with a better OS (p < 0.0001), while radiotherapy had no significant impact. The multivariate analysis confirmed that the spinal metastases at diagnosis determined a high-risk subgroup for ISS III patients with a very poor OS (p < 0.0001).

CONCLUSIONS: Spinal metastases are a negative prognostic factor for patients with MM, especially for ISS III patients, and are associated with a shorter OS. Spinal metastasis should be systemically searched for and should be included in a modified staging system to better manage these patients.