International Staging System Is Useful for Predicting Survival in Patients with Multiple Myeloma Treated with Chemotherapy ± Interferon vs Intensive Treatment.

The survival of patients with multiple myeloma (MM) varies widely from months to years. This heterogeneity is usually related to the characteristics of the disease and the patient. The identification of the factors which influence the prognosis is very important to predict outcomes, assist in the choice of the treatment and adequately stratify the patients in clinical studies. The Durie-Salmon staging is the classification most used. Recently, the International Myeloma Working Group identified 3 risk groups. They evaluated this system in patients with standard chemotherapy vs. intensive chemotherapy (autologous transplantation) but lacked to mention the paper of interferon (Griepp P. JCO 2005). We analyzed retrospectively 274 patients treated with chemotherapy (CT) ± interferon (INF) or intensive chemotherapy (CT+ autologous transplantation), during a period of 8 year (from 1997 to 2004) and compared overall survival depending of ISS risk groups among different types of treatment. Two hundred and seventy-four patients with the diagnosis of MM within the period of 1997 to 2004 at four Mexican hospitals with available data on albumin and ß₂ microglobulin were stratified according to the ISS. A total of 118 patients received chemotherapy [VAD: 104, MEL-PDN: 7, others: 7]; eighty one patients received chemotherapy plus INF as induction (n= 70) or VAD + INF in manteinance (n=11) and 75 received CT + Autologous Stem Cell Transplant (ASCT like intensive therapy) as initial therapy (No tandem transplantations were performed). The survival was estimated using the Kaplan-Meier method with differences in survival examined using the log-rank test.

The median age of the patients was 61 years (range: 31– 88), 53% female (n= 146) and 47% male (n=128). Type of MM was: IgG 66 % (n=180), IgA 19% (n=51), light-chains myeloma 13% (n=36), IgD 2% (n=7). Median monoclonal peak was 5.8 g/dL (range: 1.7–13). Whole group (n=274) was in stage I (n=49) with overall survival (OS) of 77.5%, in stage II (n=89) OS 64% and in stage III (n=136), 55.8% (p<0.024). When analyzed patients without INF or ASCT (n=118) the OS was for stage I 56.52%, Stage II 52.5%, Stage III 36.3% (p=0.21). The OS of patients that received INF or ASCT was for stage I 97%, stage II 73%, stage III 69% (p=0.009). The OS for INF group was for stage I 86%, stage II 64%, stage III 48% (p=0.006). When analyzed ASCT vs non-ASCT in whole series with or without INF we found that ASCT is better (90% vs. 56% vs. 46.6%, respectively; p<0.000) This new system of staging for multiple myeloma (ISS) is simple, is based on variables easy to be performed, and it makes it possible to identify different overall survival in patients who were treated with CT ± INF vs. Intensive chemotherapy. As of now, the results in our study group are clearly favorable for patients treated with intensive chemotherapy followed by patients using INF and could be possible modify OS in MM, keeping inmind that our series do not use MEL+PDN as primary treatment.