Thyroid Cancer in Olmsted County 1935–1965

• Published in: JNCI : Journal of the National Cancer Institute 1969-10, Vol.43 (4), p.813-820
• Main Authors: Verby, John E., Woolner, Lewis B., Nobrega, Fred T., Kurland, Leonard T., McConahey, William M.
• Format: Article
• Language: English
• Subjects: Adenocarcinoma - epidemiology; Adolescent; Adult; Age Factors; Aged; Carcinoma, Papillary - epidemiology; Child; Female; Humans; Male; Middle Aged; Minnesota; Neoplasm Metastasis; Radioactive Fallout; Radiotherapy - adverse effects; Sex Factors; Thyroid Neoplasms - epidemiology; Thyroid Neoplasms - etiology; Thyroid Neoplasms - mortality
• ISSN: 0027-8874; 1460-2105
• DOI: 10.1093/jnci/43.4.813

To evaluate the trend of thyroid cancer from 1935–65, inclusive, reports of all diagnosed cases occurring in bona fide residents of Olmsted County, Minnesota, were identified and reviewed. There were 46 acceptable cases of thyroid cancer (group 1). The average annual incidence rates (age-adjusted to the 1950 U.S. white population) increased from 1.7 to 3.1 to 3.6/100,000 population in 1935–44, 1945–54, and 1955–65. The increase, most marked between the first and second decades, is not statistically significant. There has probably been an upward trend, but it is believed to reflect an increasing awareness of the problem and improved diagnostic capabilities for thyroid cancer in the community. The age range was 11–91 years and the median age was 50 years. The female-to-male ratio was 3:1. In addition, 21 patients (18 females and 3 males) had “occult,” grade 1, papillary carcinoma of less than 1.5 cm in diameter without evidence of regional metastasis (group 2). These lesions are considered innocuous and relatively benign in the absence of clinical evidence of metastasis to cervical nodes. In 16 of the 21 cases, the diagnosis was made between 1955 and 1965. If these occult lesions were included, the age-adjusted incidence rates/100,000 population increased significantly from 2.2 to 3.7 to 6.1, respectively, in the 3 periods. The increased recognition of these occult lesions, particularly since 1955, is believed to account for this upward trend. If the increased exposure to diagnostic irradiation, radioactive fallout, and other environmental radiation has significantly affected the incidence of the thyroid cancer in adults, our survey procedure is not sufficiently sensitive to detect the effect. If the Olmsted County data were extrapolated to the population of the United States, based on the group-1 cases during 1955–65, we would expect about 7,000 persons in the country to develop clinically identifiable thyroid cancer each year.