Objective: To explore the clinical features and prognostic factors of newly-diagnosed multiple myeloma (MM) with extramedullary (EM) involvements.
Methods: The clinical features, efficacies, survival rates and prognostic factors were retrospectively analyzed in 46 MM patients with EM (group A) from January 2000 to October 2011. And another 53 MM patients without EM (group B) were selected as the controls.
Results: The median age of Group A was 58 years. Compared with group B, the incidence of EM was associated with a higher level of β2-microglobulin (β2-MG) and extensive bone disease. The most common location of EM was soft tissues. And the total effective rates of groups A and B were 58.5% (24/41) and 78.8% (41/52) respectively. The difference was statistically significant (P = 0.042). The median follow-up time was 28(2-88) months. The estimated overall survival (OS) of the patients with EM was significantly shorter than those without EM (42.6 vs 53.9 months, P = 0.009). Log-rank univariate analysis showed that the number of osteolytic lesions ≥ 3, β2-MG ≥ 5.5 mg/L, hemoglobin ≤ 110 g/L and albumin ≤ 30 g/L were poor prognostic factors in MM patients with EM. Multivariate analysis with Cox model showed only the number of osteolytic lesions ≥ 3 (OR = 2.327, 95%CI: 1.282 - 4.224) and β2-MG ≥ 5.5 mg/L (OR = 2.677, 95%CI: 1.092 - 6.566) were statistically significant.
Conclusions: Multiple EM lesions may be involved in MM patients. For the patients with EM, the response to conventional chemotherapy is poor and the prognosis is unfavorable, especially for those with a high level of β2-MG or the number of osteolytic lesions ≥ 3.