Determinants of times of appearance of radium-induced osteosarcomas in humans: age at appearance and dose

Determinants of time-until-tumor for osteosarcoma in US radium cases have been reevaluated. Classically, a minimum induction period (latency period) of about five years has been recognized, but not an expression period. Lack of long induction periods at igh doses has been ascribed to scarcity of subjects at risk. Recent experiments have suggested that induction periods are directly lengthened as doses decrease. Reanalyses of time-until-tumor data for 57 measured female osteosarcoma cases exposed to 226Ra and /or 228Ra support new interpretations: time-until-tumor for osteosarcomas is best described by age at tumor appearance, not by induction period; age at diagnosis increases as estimated initial radium intake decreases; and, there exists an expression period which can be truncated at the low end by the minimum induction period (or by age at exposure). The downturn in sarcoma incidence at very high doses is describable as the truncation of the expression period on its early side by the minimum induction period. These results depend strongly on the assumption of homogeneity of time-until-tumor processes in diial workers and in iatrogenic radium exposure cases