Stature loss following treatment for Wilms tumor

The study was designed to estimate reduction in adult stature induced by megavoltage radiation therapy (RT) of the spine in children treated for Wilms tumor and to ascertain whether the dose reduction in successive National Wilms Tumor Study Group (NWTSG) trials has mitigated late effects of RT in these children.

Effects of RT dose, age at treatment, and chemotherapy on stature of 2,778 children with Wilms or another solid tumor of the kidney were analyzed using statistical models accounting for the dependence of height on gender and advancing age. Model predictions were validated by descriptive analysis of heights measured at 17 to 18 years of age for 205 patients.

Radiation-induced reductions below normal height depended on dose, portal size, and age at treatment and were not augmented by doxorubicin or cyclophosphamide. Younger children were more strongly affected. Predicted height deficit at age 18 years was 1.8 cm for a child treated with 10 Gy to the flank at age 4 years. Observed height deficits at age 1 7 to 18 years were 4.1 cm for 57 patients who received 15-24 Gy at a mean age of 55 months and zero for 16 children who received RT doses under 15 Gy at a mean age of 83 months.

Reduction in stature following RT to the pediatric spine is dose- and age-dependent, persists into adulthood, and is not exacerbated by doxorubicin or cyclophosphamide. Average height deficits observed at maturity for children receiving doses currently recommended by the NWTSG are clinically nonsignificant.