Portal hypertension in children with Wilms' tumor: a report from the National Wilms' Tumor Study Group.

PURPOSE: This analysis was undertaken to determine the cumulative risk of and risk factors for portal hypertension (PHTN) in patients with Wilms' tumor (WT). METHODS AND MATERIALS: Medical records were reviewed to identify cases of PHTN identified with late liver/spleen/gastric toxicities in a cohort of 5,195 patients treated with National Wilms' Tumor Studies (NWTS) protocols 1 to 4. A nested case control study (5 controls/case) was conducted to determine relationships among doxorubicin, radiation therapy (RT) dose to the liver, patient gender, and PHTN. Conditional logistic regression was used to estimate adjusted hazard ratios (HR) of PHTN associated with these factors. RESULTS: Cumulative risk of PHTN at 6 years from WT diagnosis was 0.7% for patients with right-sided tumors vs. 0.1% for those with left-sided tumors (p = 0.002). Seventeen of 19 cases were evaluable for RT. The majority of cases (16/17 [94%]) received right-flank RT either alone or as part of whole-abdomen RT and received >15 Gy to the liver. Fifteen of 17 (88%) patients received a higher dose to the liver than they would have with modern WT protocols. Controlling for RT dose, the HR was 3.0 for patients who received doxorubicin (p = 0.32) and 2.8 for females (p = 0.15). Controlling for doxorubicin, the 95% lower confidence bound on the HR associating PHTN with a minimum liver RT dose of >15 Gy vs. 15 Gy vs. 15 Gy) and the development of PHTN among WT patients.