Mr. Galanti et al., IS RESIDENCE IN AREAS OF ENDEMIC GOITER A RISK FACTOR FOR THYROID-CANCER, International journal of cancer, 61(5), 1995, pp. 615-621
The association between an indicator of iodine deficiency and differen
tiated thyroid cancer has been investigated in a population-based case
-control study. This included all incident cases (N = 484) of papillar
y and follicular thyroid cancer diagnosed during the years 1980-1992 i
n a Swedish Health Care Region among residents born in Sweden, and as
many individually matched controls. Cases were included after a unifor
m review of their histopathological specimens. Residence in areas wher
e goiter had been severely endemic in the 1930s was used as exposure i
ndicator. Odds ratios (OR) and 95% confidence intervals as estimates o
f relative risk were calculated as a measure of association using logi
stic regression. A trend toward an association was found with a durati
on of residence in goiter areas between 21 and 40 years, most prominen
t among follicular cancer cases and in the group diagnosed at age grea
ter than or equal to 50 years compared to not exposed. Exposure for th
e first time during adolescence (between 11 and 20 years) was associat
ed with an increased risk of papillary cancer. This was especially evi
dent among women, both when compared to not exposed and to those expos
ed during the first year of life; the association was strengthened aft
er adjustment for duration of residence. These findings support the hy
pothesis of distinct causation patterns from iodine deficiency to the
2 most common histological types of thyroid cancer. (C) 1995 Utilty-Li
ss, Inc.