Cohort study of thyroid cancer in a San Francisco Bay area population

Abstract

Using data from a large health plan, we performed a cohort study of thyroid cancer among 204,964 persons (aged 10 -89 at baseline in 1964 -1973, 54% female) followed for a median of 20 years. Thyroid carcinoma is rare, representing 0.5% of cancers among U.S. men and 1.7% cancers among U.S. women, but remains the most common malignancy of the endocrine system. 1 Its incidence increased from 1987 to 1991 in the United States, 2 is greater in women than in men and peaks between the ages of 25 and 65. 3,4 The prognosis of well-differentiated, localized thyroid tumors is extremely good. 1 Persons considered to be at high risk include those with a history of radiation treatment during infancy and childhood, 5,6 those with exposure to nuclear testing 7 or to nuclear reactor accidents 8 and those with benign conditions of the thyroid gland. 9 -13 Other putative determinants include diet (notably iodine deficiency or excess), 14,15 hormonal, reproductive 16 -20 and genetic factors. 21,22 Other less well-studied potential risk factors include smoking, alcohol intake, 23 body size and weight gain. 18,24 In this report, we evaluated several potential predictors of thyroid cancer (including demographic, behavioral, medical and reproductive factors as well as occupational exposures) in a large, well-defined, multi-ethnic cohort of men and women enrolled in a health-maintenance organization (HMO) in northern California and followed for up to 33 years. MATERIAL AND METHODS Study design and proceduresWe used a historical cohort study design with measurement of characteristics at baseline (1964 -1973) and prospective follow-up of events from baseline through the end of 1997. The cohort was composed of 95,058 male and 112,838 female subscribers of the Kaiser Permanente Medical Care Program of Northern California, aged 10 -89, who underwent multiphasic health checkups between 1964 and 1973 in San Francisco or Oakland. Of the original cohort, 28 women and 6 men were excluded for having a prior diagnosis of thyroid cancer before the multiphasic checkup. An additional 2,395 women and 503 men were excluded for having a self-reported history of thyroid operation (though the extent of surgical removal was unknown). Thus, the final sample of persons free of thyroid cancer and with an intact thyroid gland consisted of 94,549 men and 110,415 women.Northern California Kaiser Permanente members constitute an ethnic and socio-economic mix that is generally representative of the local population, except that the extremes of wealth and poverty are under-represented. 25 If study participants attended more than 1 checkup, only the data from the first were used.The multiphasic checkup collected information on several demographic factors (age, gender, race/ethnicity and educational attainment), anthropometric measurements, health behaviors (cigarette smoking and alcohol consumption), physiological characteristics (including reproductive factors), medical conditions and occupational exposures using standardized instruments and procedures previously...

Body size and thyroid cancer in two million Norwegian men and women

“…Hence, our estimates were not diluted by a possible influence of individuals weight on the disease. Iribarren et al (2001) evaluated several potential predictors of thyroid cancer in a large American cohort with long follow-up, including more than 200 000 persons. Despite the large size of the cohort and the long follow-up, only 196 thyroid cancers were observed.…”

A Case-control Study in Hiroshima and Nagasaki Examining Non-radiation Risk Factors for Thyroid Cancer

“…Such potential confounding bias associated with socioeconomic status or health consciousness may not be small for papillary adenocarcinoma of the thyroid gland, which is of a highly dormant and silent nature as indicated by a high prevalence rate (6-36 %) of latent papillary carcinoma at autopsy series. 18 Although not all, [19][20][21][22] several previous studies of thyroid cancer have reported a reduced risk of thyroid cancer significantly, [23][24][25][26] or not significantly associated with cigarette smoking. [27][28][29][30][31][32][33] Although results are less consistent, 20,22,24,29,[31][32][33] several studies have also suggested reduced thyroid cancer risk associated with alcohol drinking.…”

“…The inverse relationship between these two factors and thyroid cancer is strange in view of the finding that smokers have increased risk of other thyroid pathologies, such as goiter and nodules, 57,58 which predispose individuals with these conditions to an increased risk of thyroid cancer. In addition to learning more about the hormonal and other biological effects of smoking and drinking, further epidemiologic research is needed to clarify the nature of the inverse association with smoking and drinking, as prospective data available to date 20,22 have failed to confirm this association. Thyroid cancer is relatively infrequent and less fatal than most other malignancies, but presents a significant morbidity burden in the community and warrants more epidemiologic attention than previously given.…”

Risk factors for thyroid cancer: A prospective cohort study

“…These studies have suggested no association with age at menarche, duration of oral contraceptive use, postmenopausal status, ever use of hormone replacement therapy, age at first birth, [18][19][20] smoking, or alcohol consumption, 20 and only 1 out of 3 reported a positive association with parity.…”