[1] CROSS CANC INST,DEPT PEDIAT,EDMONTON T6G 1Z2,ALBERTA,CANADA
[2] UNIV ALBERTA,FAC MED,EDMONTON T6G 2E1,ALBERTA,CANADA
[3] MASSACHUSETTS GEN HOSP,CTR CANC,BOSTON,MA 02114
[4] CASE WESTERN RESERVE UNIV,SCH MED,DEPT PEDIAT,CLEVELAND,OH 44106
[5] NCI,CLIN EPIDEMIOL BRANCH,CLIN STUDIES SECT,BETHESDA,MD 20892
[6] HARVARD UNIV,SCH MED,DANA FARBER CANC INST,DEPT MED,BOSTON,MA 02115