Abstract
During the two years from 1965 to 1966, the authors carried out a survey of thyroid cancer combined with goiter in an unselected population living in nine nongoitrous areas in Nagano Prefecture, Japan. In the survey, 30, 359 subjects were examined. The total number of goiter patients found in the population was 1, 228; i. e. 4.0%(1.7 males; 6.1 females) of the population examined. The 353 cases of the 1, 228 patients were clinically diagnosed as nodular goiter, in which 234 cases were found to have indications of surgical removal of thyroid nodules, and 186 of the 234 cases were operated on. In the clinical and histological studies, 40 cases (11 males; 29 females) were diagnosed as thyroid cancer. The following were observed regarding thyroid cancer: 1) Prevalence rate of thyroid cancer was 1.3 (0.8 males; 1.8 females) per 1, 000 subjects examined. 2) Prevalence rate of thyroid cancer was not the same in different areas and was higher in the age-group over thirty than in the age-group under twenty-nine. 3) About 20% of the nodular goiters which were operated on was found to be thyroid cancer and 15.9% which was clinically diagnosed as benign nodular goiter before operation was found to be thyroid cancer. 4) Most of patients with thyroid cancer were unaware of the presence of goiter and showed no symptom. 5) About one third of thyroid cancer were in advanced stadium clinically, and two of them were too advanced to be operated on. 6) The 38 cases which were operated on were histologically diagnosed as papillary adenocarcinoma, with the exception of two cases of follicular adenocarcinoma. 7) There is a distinct difference between the prevalence rate of thyroid cancer and the mortality or morbidity (incidence) rate of thyroid cancer, and the former is significantly higher than the latter.
