Acta Oncol 1992;31(4):403-7
Tumors after radiotherapy for thyroid cancer. A case-control study within a
cohort of thyroid cancer patients.
Hall P, Holm LE, Lundell G, Ruden BI.
A case-control study of Swedish thyroid cancer patients was conducted to
evaluate the possible influence of 131I treatment and external radiotherapy on
the risk of developing a subsequent cancer. Both cases and controls derived from
a cohort of Swedish thyroid cancer patients treated with 131I (n = 834) or by
other means (n = 1,121). Thirty-six breast, 13 stomach, 12 kidney, and 5 bladder
cancers were found more than 2 years after 131I treatment/thyroid cancer
diagnosis. Individual, absorbed dose in the organs was calculated by using ICRP
tables, administered activity of 131I, and 24-h 131I uptake. In studying the
effect of 131I and external radiotherapy no statistically significant
dose-response relationships were found for cancers of the breast, stomach,
bladder or kidney. When the absorbed dose from 131I was analyzed separately the
risks remained essentially the same. The present follow-up time and the
relatively low absorbed dose that the patients received from 131I and external
radiotherapy necessitate studies with a longer follow-up time or a larger
patient material before more firm conclusions can be made.
