Epidemiology of thyroid cancer: a review with special reference to Gulf Cooperation Council (GCC) states.

A wide variation in incidence of thyroid cancer according to age, sex, ethnicity and geographic region was observed. In general, it occurs more frequently in women than men and a substantially higher rate was observed particularly during fertile period of women compared with men of the same age. Papillary carcinoma is the most prevalent histological type, irrespective of gender and conditions like iodine level. Over the years the incidence of thyroid cancer, especially papillary type, increases around the world. Ionizing radiation, in particular radiotherapy to head and neck region was the most established risk factor for thyroid cancer. Goiter, miscarriage or abortion (particularly in the first pregnancy) may also predispose to thyroid cancer risk. Cigarette smoking and use of contraceptives may be modifier of thyroid cancer risk. In all the GCC states thyroid cancer is the second most common cancer except in Babrain and Kuwait (where it stands third). During the five year peribd (1998-2002) 549 male and 1898 female thyroid caneers were diagnosed in all the GCC states. Papillary carcinoma is the predominant histological type followed by follicular carcinoma in both genders. Among females, Qatar has the highest incidence with an age standardized incidence rate of 13.5 per 100,000 followed by Kuwait (7.7), Bahrain (7.6), Emirates (6.0), Oman (5.9), and Saudi Arabia (5.0). There were at least 2.6 female thyroid cancer cases (in Kuwait) for each male thyroid cancer case and this goes up to 6.6 in Babrain. Incidence of thyroid cancer in the GCC states is closer or higher than that of some of the developed countries.