Impact of chromosome 13 deletion and plasma cell load on long-term survival of patients with multiple myeloma undergoing autologous transplantation.

High-dose therapy (HDT) followed by autologous stem cell transplantation (ASCT) is the most common treatment for patients under 65 years of age with multiple myeloma (MM). In this study, we present a retrospective analysis of the prognostic impact of different factors in patients who have received this treatment as first line therapy in our centre. Abnormalities in chromosome 13 were identified by fluorescence in situ hybridization at the time of diagnosis. The median overall survival (OS) and progression-free survival (PFS) from transplantation time in the whole group of 193 patients were 90 and 48 months respectively. The median follow-up was 65 months (range: 6-186 months). The complete remission (CR) rate in patients with and without del(13) was 31 and 40% respectively whereas the median OS in patients with del(13) was 58 months but not reached in patients without del(13) (p=0.006). The PFS was 26 months in patients with del(13) and 84 months in those without del(13) (p=0.001). The transplantation related mortality was 2.5% both in the absence and presence of del(13). Patients who achieved CR following ASCT had longer OS and PFS when compared to those who only achieved partial remission. Thus, this study confirms the role of del(13) as a marker of poor prognosis. Multivariate analysis showed that the existence of del(13) was the only single independent factor effecting survival (p=0.001). In patients without del(13), the prognostic impact was even stronger when combined with the plasma cell load in the bone marrow (p=0.020), whereas the plasma cell load had no effect on survival of patients with del(13). Overall, the absence of del(13) in combination with low plasma cell infiltration at diagnosis predicts the best survival.