Survival after relapse in children with solid tumors: A follow-up study from the Italian off-therapy registry

Background. Despite the increased survival of children with solid tumors, a significant proportion of cases still relapse following treatment discontinuation, and knowledge about the long-term outcome of this selected group of patients remains incomplete. Objective. To describe the long-term outcome of children treated for a solid tumor who relapsed after the elective end of therapy, and to explore factors associated with survival. Methods. All patients with the selected diagnoses-Hodgkin disease (HD), neuroblastoma (NB), tumor of the central nervous system (CNS), Wilms tumor (WT), or soft tissue sarcoma (STS)-enrolled in the Italian Pediatric Off-Therapy Registry in the period 1980-1998 were evaluated. Out of 3,927 patients, 694 had relapsed after treatment suspension; 639 were available for analysis. Survival and event-free survival were estimated by the Kaplan-Meier method. The log-rank test was used to assess differences in survival among the various types of cancer considered. Multivariate Cox proportional hazards analysis was adopted to explore possible prognostic factors. Results. There were 335 deaths: most of them (93%) were related to the primary cancer. The overall survival rate after relapse was 38% (95% CI 33-42) at 5 years, and 32% (95% CI 27-36%) at 15 years, while event free survival was 31% (95%, CI 26-35) and 26% (95% CI 22-30%), respectively. There were significant differences according to the original diagnosis, with patients with HD doing better, and those with NB, CNS, and STS worse. No improvement of prognosis was evident over time. Post-relapse stem cell transplantation was associated with decreased risk of death only in the first year, not thereafter. Conclusions. Overall, patients with solid tumors who relapse after treatment discontinuation have a poor outcome, but significant differences exist according to the tumor types.