Re: Fallout blamed for thyroid cancer

[Wes Van Pelt <VanPeltW@idt.net>]

Otto G. Raabe wrote:
> 
> September 17, 1998
> Davis, CA
> 
> At the American Cancer SOCIETY website http://www.cancer.org I found that
> the U.S. death rate from thyroid cancer has decreased by about 20% since
> 1974. However, this may reflect improved treatment since currently about
> 90% of thyroid cancer cases are cured. The current death rate is about 0.4
> cases per 100,000 people in the U.S. It may also mean that there were
> actually few if any cases caused by the I-131 doses associated with weapons
> tests.
> 
> Otto

Otto and All,

As you correctly imply, in order to assess the thyroid cancer trend, one
needs to review the INCIDENCE rates rather than mortality rates. It
seems that there is no national cancer registry for incidence, only
mortality.  I found the following very interesting abstract on the Web:

Time trend and age-period-cohort effect on incidence of thyroid cancer
in Connecticut, 1935-1992.

Zheng T, Holford TR, Chen Y, Ma JZ, Flannery J, Liu W, Russi M, Boyle P

Department of Epidemiology and Public Health, Yale University School of
Medicine, New Haven 06510, USA. 

Recent studies from Europe suggest a continuing increase in thyroid
cancer, but it is unclear whether this trend also applies to the United
States. The current study examined the long-term trend of thyroid cancer
in Connecticut. Our results show that the overall age-adjusted incidence
rate of thyroid cancer has been increasing in Connecticut, from
1.30/100,000 in 1935-1939 to 5.78/100,000 in 1990-1992 in females, and
from 0.30/100,000 in 1935-1939 to 2.77/100,000 in 1990-1992 in males.
The increase mainly comes from papillary carcinoma of the thyroid. The
birth cohort analyses indicate that the increase in thyroid cancer
occurred among cohorts born between 1915 and 1945, which experienced an
increase of 31.4% every 5 years in males and 17.3% in females over the
period 1960-1979. For those born since the 1945 cohort, the incidence
has been decreasing, at rates of 9.3% and 8.3% every 5 years over the
period 1975-1992 in males and females, respectively. Age-period-cohort
modeling results also suggest a strong birth cohort effect on the
observed time trend in both sexes, which closely follows the
introduction of radiation treatment of benign childhood conditions in
the head and neck between 1920 and the 1950s in the United States. Our
results are consistent with the suggested radiation hypothesis,
indicating that radiation treatment of benign childhood conditions in
the head and neck is largely responsible for the observed increase of
thyroid cancer in Connecticut. 


regards, Wes
-- 
Wesley R. Van Pelt, Ph.D., CIH, CHP                KF2LG
President, Van Pelt Associates, Inc.     
Consulting in radiological health and safety.
mailto:VanPeltW@IDT.net        
http://shell.idt.net/~vanpeltw/index.html
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