Objective: To examine the descriptive epidemiologic features of incident th
yroid cancers diagnosed among Los Angeles County residents between 1972 and
1995.
Methods: The Los Angeles County/University of Southern California Cancer Su
rveillance Program (CSP) collected data on 8820 newly diagnosed thyroid can
cer of cases occurring in Los Angeles County. Average annual age-adjusted i
ncidence rates were calculated to study the epidemiology of each of the maj
or histologic types of thyroid carcinoma.
Results: For all races combined, the age-adjusted incidence rates were 2.5
per 100,000 males and 6.0 per 100,000 females. Differences in incidence by
ethnicity were particularly striking, with Filipinos demonstrating the high
est incidence rates (4.44 per 100,000 males, 11.3 per 100,000 females). Ove
r the 23-year period, thyroid cancer incidence rates increased 1.5% per yea
r for males and 1% per year for females. By histology, papillary carcinoma
rates increased over time and follicular carcinoma rates decreased. Non-Spa
nish surnamed white men employed in certain white-collar occupations and ra
diologic technicians were at greater risk of thyroid cancer.
Conclusions: Additional research on the epidemiologic risk factors for thyr
oid cancer, particularly for gender and ethnicity, is needed to explain the
marked elevated incidence rates among females and the Filipino population
in Los Angeles County.