Abstract / Summary
Abstract Background Autologous bone marrow transplant (ASCT) remains the cornerstone of multiple myeloma (MM) treatment. In developing countries, a lack of access to resources may lead to prolonged wait lists for ASCT, where patients are exposed to relapse and other morbidities. This project aims to evaluate the time from diagnosis to transplant interval, both as a continuous and categorical variable, and measure its effect on progression-free survival (PFS) of newly diagnosed transplant-eligible patients enrolled in our transplant center over a span of nearly 30 years. Methods We referred to a retrospective registry of ASCTs in Shariati Hospital, Tehran, Iran. Patients were included if they had a diagnosis of MM and underwent ASCT before their first relapse. The primary predictor was time of diagnosis to start of high-dose chemotherapy, and the primary outcome was PFS. PFS was expressed as both a continuous and categorical variable, and data were analyzed using the Cox proportional model of hazard ratios. To explore non-linear relationships, we utilized spline modeling, and to explore potential clinically relevant thresholds, we chose ROC-derived binary cutpoints, as well as a 12-month threshold from existing literature, and performed additional Cox proportional modeling. Results The median interval to transplant was 13.3 months (IQR 9.7–19.4). Early PFS was comparable across all groups, but patients with the longest delays experienced a pronounced decline in long-term outcomes. At five years, PFS was 35.6% for the longest-interval group compared to 46.1% for the intermediate group. Ten-year PFS dropped to 19.8% versus 30.3%. Cox models confirmed a higher risk of relapse or death with prolonged intervals (adjusted HR 1.37; 95% CI 1.09–1.72), while outcomes for the shortest-interval group were similar to the intermediate group. Each additional three-month delay was associated with a slight but noticeable increase in hazard (adjusted HR 1.02). ROC-based analyses suggested that intervals beyond roughly 17–19 months consistently predicted worse PFS. Conclusions Extended delays in transplantation (beyond 17 months) correlated with poorer progression-free survival, whereas shorter or moderate delays appeared less harmful. These results highlight the importance of timely access to ASCT while suggesting that small, unavoidable delays may be clinically acceptable.