A recent analysis of cancer incidence at ages 12 to 55 compared data for survivors exposed in utero with those exposed in early childhood. For the in utero survivors there was a significant dose response with an excess relative risk (ERR) of 1.0 per Gy, a risk not significantly less than that for survivors exposed during the first five years of life (ERR = 1.7). However, the temporal patterns of the excess absolute rates which increased rapidly with age for early-childhood exposures did not increase following in utero exposure, but the difference between the two was not statistically significant at this time. It can at least be concluded that adult cancer risk from in utero exposure is not greater than that from early childhood exposure.

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