Clinical Course and Impact of Breaks in Therapy for Children With Relapsed/Refractory Solid Tumors

Pediatric relapsed or refractory (R/R) solid tumors carry a dismal prognosis, and postrelapse patient experiences are not well described. We present postrelapse outcomes, including number of R/R events and subsequent therapy regimens. We analyze whether breaks (>30 days) between events and subsequent therapies affect survival and the associated decision-making rationales.

We reviewed data for patients with R/R extracranial solid tumors treated at Texas Children's Hospital between 2005 and 2023. Descriptive analysis was performed along with univariate chi-square and independent sample t-tests. Cox regression analysis was used to evaluate postevent survival (PES).

Of the 466 patients (female: 47%; median age: 8.7 years), most common diagnoses were neuroblastoma (21.5%), rhabdomyosarcoma (19.1%), and osteosarcoma (16.1%). Patients had a median of 3 (interquartile range [IQR]: 1-4) R/R events with a median of 93 (IQR: 52-200) days between events. Of 438 patients who received ≥1 postevent therapy regimen, 116 (26.5%) experienced ≥1 break. Reasons for breaks varied evenly between intentional/goal-concordant and undesired delays. Median PES for all patients was 12.9 (IQR: 5.8-31.4) months. In a multivariable Cox regression model, taking a >30-day break in disease-directed therapy was associated with prolonged PES (hazard ratio 0.58 [95% CI 0.45-0.76], p < 0.001).

Most children with R/R solid tumors experience multiple events and therapy regimens without a break. Presence of a >30-day break did not negatively affect survival, implying that time between therapy regimens can safely be offered to select patients to promote quality of life and thoughtful decision-making, without compromising survival.