We analyzed participants in the Childhood Cancer Survivor
Study (CCSS), a cohort of 5-year survivors of childhood cancer diagnosed
before the age of 21 years between 1970 and 1986 at one of
26 participating institutions. Participants and data collection
methods were described previously [9,10]. The institutional review
board at each institution approved the CCSS protocol. Informed
consent was obtained from all participants or their parents. We
focus on female survivors of a pediatric CNS tumor or leukemia
who were treated with spinal irradiation but with no other radiation
field near breast tissue (women also treated with high abdominal
fields or total body irradiation were excluded). Delivered
spinal irradiation doses were abstracted from medical records.
Average breast doses were calculated using radiation treatment
parameters as previously described [11]. To summarize the average
breast dose across all participants, we present a weighted average
of the average nipple dose across cohort participants. Radiation
doses to the left and right ovaries were also estimated. The right
and left ovary doses were equivalent in all but four women, and
the average is presented. The cyclophosphamide equivalent dose
(CED) was used to quantify cumulative alkylating agent exposure
and was calculated as has been described previously [12].