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

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.

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.

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).

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.