Indian Write-Ups

Cancer as a disease has been well recognized in India since Vedic times (41) but its magnitude and problems have only been identified since the beginning of the century. Paymaster (31) studied the pattern of cancer in India by scrutinizing the relative frequency data from cancer hospital in the country. Apart from cancers associated with tobacco chewing and smoking habits, an epidemiological study of Thyroid Cancer (TC) in India has not been carried out in detail. It is well known that TC is infrequent in many parts of the world and its etiology is yet to be known. An attempt has been made in this article to identify the epidemiological aspects of this cancer in India, its status in the world, current knowledge regarding the associated factors and high-risk population.

Clinical Epidemiology

At the Tata Memorial Hospital (TMH), Mumbai, TC has been recorded since the inception of this hospital in 1941.

Table 1 : The decade wise relative frequency of thyroid cancer at TMH - 1941-93

In the Year 1941, six TC cases were recorded out of a total of 1,100 cancer cases diagnosed in the hospital. Ever since then the relative frequency of this cancer has increased from 0.5% in 1941 to 1.2% in 1993, Table 1. Ninety percent of the cases were microscopically confirmed. During the period 1941-93; 3,448 (0.9%) TC cases were diagnosed out of a total of 3,72,930 cancer cases. The microscopic confirmation was about 72% in 1941-50, which increased to over 98% in 1991-93. Advancement in diagnostic techniques and the introduction of Fine Needle Aspiration Cytology (FNAC) have greatly improved the percentage of microscopic confirmation of the disease. The gender ratio for TC is about 1:1.4 (M:F) in the predominance of females over males was seen in all the years. The average ages for males and females based on hospital data were 45.2 years and 41.5 years respectively.

Table 2 : Decade wise histological classification of thyroid cancer – TMH

Among 2,834 TC seen over last 50 years, Papillary Carcinoma (PC) was the predominant type (883 cases –31.2%) followed by Follicular Carcinoma (FC 785 cases – 27.7%) and Medullary Carcinoma (MC 231 Cases – 8.2%). In a 100 cases (3.5%) mixed classification of two major types namely the papillary and follicular variety was observed (Table 2). Medullary carcinoma type has been identified in our data in the late 60’s.

The gender ratio and average age of patients with TC according to histological classification based on 1554 cases seen during the period 1984-82 are presented in Table 3, (9). The female predominance was evident only in the papillary and follicular variety whereas male predominance was observed among medullary type. Though the average age for males in three common histological types did not show much variation, the average age among females in the papillary and medullary type was lower than for males.

Table 3 : Histological type and average age according to sex in TMH data 1984-92

With the establishment of the National Cancer Registry Program (NCRP) by the Indian Council of Medical Research (ICMR), New Delhi, cancer registries in the three main cancer hospitals namely in Mumbai, Madras and Bangalore and three general hospitals in Chandigarh, Dibrugarh and Thiruvananthapuram were initiated in 1984. NCRP has collected data (Table 4) on over 1, 77,318 cancers in males and 1,61,198 cancers in females during the period 1984-93 from six cancer registries (27).

Table 4: Number and percentage of thyroid cancer in six Hospital cancer registries by sex 1984-93