Efficacy and safety of high-dose chemotherapy with autologous stem cell transplantation in senior versus younger adults with newly diagnosed multiple myeloma.

We retrospectively studied 340 fit patients with multiple myeloma (MM) who underwent autologous stem cell transplantation (ASCT). We hypothesized that progression-free survival (PFS) of older patients was non-inferior to that of younger patients after ASCT. Our null hypothesis was that the PFS hazard ratio (HR) for a 5-year increase in age was ≥1.05; the alternative (non-inferiority) hypothesis was that the HR was ≤1. The observed HR was 0.94 (95% confidence interval [CI] 0.86-1.03); since the CI upper bound was <1.05, we reject the null hypothesis and conclude that PFS in older patients was at least as good as in younger patients. We cannot reject an analogous null hypothesis for overall survival (HR 1.06 [95% CI 0.94-1.19]), since the CI upper bound >1.05. Toxicity was similar across ages and transplant-related mortality was minimal. 28% of subjects <65 versus 45% of those ≥65 received maintenance therapy. In summary, ASCT prolongs PFS equally well in older vs. younger adults. Although we cannot exclude maintenance as a confounder, these data support ASCT for fit seniors with MM.