Histologic trends in thyroid cancer 1969–1993: A clinico-pathologic analysis of the relative proportion of anaplastic carcinoma of the thyroid

Abstract

Background It was observed that new presentations of anaplastic carcinoma of the thyroid had become infrequent in the last two decades. Methods All cases of thyroid cancer seen at our centre between 1969–1993 (n = 2921) were classified as papillary 49%, follicular 34%, medullary 7.5%, anaplastic 4.7%, and other 4.8%. The total number of thyroid cancers show a 3.5‐fold rise. Results The differentiated thyroid cancers show a significant rising trend as against the relative proportion of anaplastic carcinoma, which shows a significant decline (P = 0.002). Clinicopathologic data on 124 patients of anaplastic carcinoma revealed 50% patients had either long‐standing goitres, previous thyroid abnormalities, or associated differentiated thyroid carcinoma on histology. Conclusions The decline in the relative proportion of anaplastic carcinoma may in part be explained by the clinicopathologic findings or it may be attributed to histological reclassification. © 1996 Wiley‐Liss, Inc.

Clinico-pathological Features of Thyroid Cancer as Observed in Five Referral Hospitals in Iran

“…Several case-control studies have shown that iodine deficiency leads to an increased relative proportion of FTC compared with areas of endemic goiter (12,24) (1996); Harrach and Williams (1995)) have reported a higher incidence of FTC ( 5/30 Á/40%), which may be more prominent in men, in iodine-deficient areas (10, 24 Á/26). Following the introduction of iodine supplementation in iodine-deficient regions, however, an increase in the relative proportion of PTC has been recorded, usually concurrent with a drop in frequency of the follicular and anaplastic types (13,26,27).…”

“…Our findings argue against the suggested cause-and-effect relationship between iodine deficiency and FTC. The lower occurrence of FTC may also explain the low frequency of anaplastic carcinoma in our study (27). The significance of this pattern of distribution lies in the fact that PTC has a better prognosis than FTC (13,24).…”

“…It seems that when endemic goiter is a frequent feature in a region, patients tend not to worry about goitrous growths until the onset of serious symptoms, by which time small, well-differentiated thyroid carcinomas have been replaced by often larger and less-differentiated types (27). In our study, however, anaplastic tumors were on average smaller, but not significantly so, than the differentiated types.…”

Endocrine cancer in Iran: Based on cancer registry system

“…[8] This decline in the relative proportion of anaplastic carcinoma, may in part be explained by the clinicopathological findings or attributed to histological reclassification. [26] Patients with anaplastic thyroid carcinoma in this study were older than the patients in other groups, which is consistent with previous studies. [8] While the study indicates low frequency of endocrine cancers in Iran, it should not be neglected that it was limited to only four provinces of the country and it was limitation of data.…”

A case of primary thyroid squamous cell cancer: transformation from benign tumour associated with chronic thyroiditis?

“…Although the aetiology of SCT has not been clarified, currently proposed hypotheses include: (1) squamous metaplasia superimposed on some underlying pathology such as chronic thyroiditis; (2) squamous differentiation from papillary cancer or anaplastic cancer; and (3) embryonic rest in which squamous cell cancer develops in remnants of the ultimobranchial body or thyroglossal duct 1 , 2. The most influential trigger of the cancer transformation is irradiation 10 , 11…”