Document gbgjKeq2EM9NRkOnm258gGjQV

HFM - 003507 oid hyperplasia and cervical lymphadeni apparent thyroid cancer by country a|id tis in infancy and early childhood, and race may -reveal important interactions was consistent with' the hypothesis that between host and environmental factors. ionizing radiation was a cause of thyroid However, such comparisons must be$i- cancer in children and young adults. terpreted cautiously since they are sub Whether, increasing incidence rates are . ject to variations in the procedures used. real or artifactual depends upon the de for neoplastic classification and registra gree to which they have been influenced tion and in the quality of diagnostic apd by changing diagnostic criteria and com therapeutic services. The pattern of geo pleteness of reporting. For example, the graphic and racial differences in the'in occult sclerosing non-encapsulated papil cidence of clinical thyroid cancer should lary carcinomas and intraglandular en be distinguished from that observed for capsulated follicular carcinomas with occult thyroid cancer. minimal vascular invasion have received In 5,636 consecutive autopsies on can increasing recognition during the past 20 cer patients at Memorial Hospital, the years. In their review of thyroid cancer in prevalence ratio of occult thyroid cancer Olmsted County (1935-1965), Verby et al.6 as an independent primary cancer was 6.4 attributed the observed substantial in per 1,000 autopsies. The method of exam crease in incidence to the greater recog ination consisted usually of a single section nition of occult papillary tumors during from each lobe when no tumor was grossly the 1955-1965 decade. visible. The peak prevalence in women. Variations in the incidence of clinically was 19.6 per 1,000 at 20-29 years of age, H 0 v 1 i.l *> A CANCER JOURNAL FOR CLINICIANS 1 t and 10.4 per 1,000 in men at 30-39 years.: Unlike most carcinomas, there was no indication that subclinical thyroid cancer increases with kscreasihg age.TSampsbh et al.8 arrived at a similar conclusion in their autopsy study in Hiroshima and Nagasaki. In autopsy studies conducted in the United States where the thyroid gland was examined meticulously, the observed prevalence ofoccult thyroid cancer varied between 1.0:5.7 (percent. Whereas the prevalence due to clinically apparent thyroid carcinoma predominates in wornen, occult thyroid cancer occurs almost as frequently inmen.-io The prevalence of latent thyroid cancer (i.e., 1.5 cm. or less in maximum dimension)diagnosedatautopsyintheHawaiian iapanese and native Japanese (17.9-24 percent) is at least four times that observed in comparable autopsy studies from Cam ada and the continental United States1'-0 However, clinically apparent thyroid cancer incidence rates in the Hawaiian'Japanese and the native Japanese are not rig? nificahtty different. from those in the . Hawaiian whites and the continental United States whites (Table l.)m5The. ageadjusted incidence in the Hawaiian Chinese women is greater than that observed in the Japanese and Caucasian groups in Hawaii and is almost 18 times that reported in Singapore Chinese women, More recent informationon this finding has been furnished by Koloriel and Reilahan from the Hawaii Tumor Registry (Table II).These rates were based upon a total of 110 patients in 1960-1964 and 184 patients in 1968-1972. The small number of cases in each racial group allowed for wide sampling fluctuations, The rates in the Chinese and HavypJian women were in contrast to those seen in the Japanese and Caucasian women: For VOL.28,NO.2MARCH/jAPRI ROnl; 6S'