100 NEUROBLASTOMAS DETECTED THROUGH A MASS-SCREENING SYSTEM IN JAPAN

Background. In Japan, a nationwide mass screening (MS) program for pre clinical detection of neuroblastoma in infants was done by measuring u rinary vanillylmandelic acid and homovanillic acid at the age of 6 mon ths. In this study, clinical, histopathologic, and biologic features o f 100 neuroblastomas detected through the Japanese MS are presented. M ethods. Clinical data of the MS cases were collected and histologic an d biologic studies performed on the surgically resected neuroblastomas . Histopathologic evaluation was done including the Shimada classifica tion (all tumors), N-myc oncogene status (58 tumors), and ploidy analy sis (31 tumors). The serum ferritin level was measured before surgical intervention in 27 cases. Results. The primary tumor sites of these c ases were adrenal (69), retroperitoneum (21), and mediastinum (10). Th e tumors were clinical Stage I(31), II(31), III(19), IV(8), and IV-S(9 ); two children had bilateral primary adrenal tumors. Ninety-three per cent (93/100) had favorable histology ; 100% (58/58) had nonamplified N-myc oncogene expression; 81% (25/31) showed a favorable ploidy patte rn, and 96% (26/27) had normal serum ferritin levels. To date, all chi ldren in this series are alive and well, although a total of 13 tumors were associated with one or two poor risk factors; 6 had unfavorable histology (UH), 5 had an unfavorable ploidy (UP) pattern, one had UH a nd UP, and one had an elevated ferritin level. Conclusions. The majori ty of neuroblastomas detected through the MS showed favorable biologic factors (biologically favorable group). However, there was a small gr oup with histopathologic and/or biologic unfavorable factors. Patients with unfavorable factors apparently benefit most from early surgical intervention.