Autologous Stem Cell Transplantation for Multiple Myeloma in Patients over 70 Years: A Matched Comparison with Patients under 65 Years.

Background: High dose therapy with autologous stem cell rescue has been shown to prolong survival in patients with multiple myeloma in randomized controlled trials. However, most of the prospective studies have included younger patients, usually 65 or less. It is important to have a better understanding of the outcome of transplantation in the older patients given the median age of onset of myeloma of 65 years. We retrospectively reviewed our institutions experience with high dose therapy for patients over 70 years.

Methods: We identified 35 patients with multiple myeloma, from the transplant database, who were at or over the age of 70 at the time of their high dose therapy. We matched these patients to 70 patients (two matches for each patient), based on stage at transplant (primary refractory, plateau phase, relapse off therapy, or relapse on therapy), Durie Salmon stage, high or low labeling index, conventional cytogenetics (abnormal vs normal), presence or absence of circulating plasma cells at time of transplant, and whether cyclophosphamide was used as part of mobilization in that order of priority.

Results: The median age of the two groups were 55.3 (Range 37.3–64.8) and 71.7 (Range 70–75.8) years at the time of transplant. The median time to transplant from diagnosis was similar (6.4 for the older patients compared to 6.9 months for the other, P = NS). Ten of the 35 older patients received reduced dose melphalan (140 mg/²)) compared to 3 patients in the control group; P < 0.01. The median follow up from transplant was 10.1 months for the older patients compared to 18 months for the control group. The overall response rate was similar for the two groups (97.1% for the older patients compared to 95.5 for the control group). Eleven (31%) of the older patients and 17 (24%) of the control patients achieved a CR (P = NS). The post transplant progression free survival estimate at 1 year post transplant was 65.3% for the older patients compared to 66% for the control group (P = 0.3)The two year estimated overall survival from transplant was similar in the two groups; 58% for the older patients compared to 67% for the control group. The overall survival from diagnosis was similar for the two groups (P = 0.6). The median number of days hospitalized was 9 days for the older population compared to 5 days for the control group (P = 0.37). Four patients died within the first one hundred days, one (3%) among the older patient group and 3 (4.3%) in the control group.

Conclusions: High dose therapy and autologous stem cell transplantation is feasible in selected patients with multiple myeloma over 70 years. It is likely that these older patients were selected based on their overall performance status, a factor that is difficult to analyze in this retrospective review. Nearly 70% of the elderly patients received full dose melphalan for conditioning (200 mg/m²). The toxicity of transplant as well as the outcome appears to be very similar to the younger patients. Patients with multiple myeloma should not be excluded from high dose therapy solely on the basis of their chronological age.