Mortality among children with rhabdomyosarcomas of the alveolar histologic subtype.

Of 116 patients with rhabdomyosarcoma of the alveolar histologic subtype who entered the Intergroup Rhabdomyosarcoma Study (IRS) from 1972 to 1978, there were 72 deaths (63%), compared with a mortality of 39% among patients with all nonalveolar types combined. The subgroup with alveolar histology contributed greater than 29% of the total mortality, although it represented 20% of the total patients (p less than .001). This recurrence rate reflects increased local, regional, and distant relapse. Differences were most marked in patients with grossly excised tumors (clinical groups I and II) in which the mortality was 44% in patients with alveolar tumors (48 patients) versus 13.5% in those with embryonal histology (111 patients), and 16% in all patients with nonalveolar tumor types. When survival was influenced by primary tumor site this reflected, in most body areas, an increase in the proportion of patients with the alveolar histology in that site. Patients with unresected or disseminated tumors (clinical groups III and IV) of the alveolar subtype have initial response rates to VAC and radiotherapy which are similar to those of patients with tumors of other cell subtypes (70% for group III and 50% for group IV). In these clinical groups, the differences in survival related to histologic subtype are not significant. The presence of the alveolar histologic subtype represents a rational basis for employing more intensive therapy in the management of patients with rhabdomyosarcomas.