Thyroid cancer (TC) is a common malignancy encountered at King Faisal Specialist Hospital and Research Centre (KFSH&RC). Of 19,885 different malignant tumors seen during the period from 1975 to 1989, there were 875 cases (4.4%) of TC. Of 1374 tumors of endocrine glands seen during the same period, 67% were thyroid neoplasms. TC represented 7.5% (618 cases) of all neoplasms in the females, second only to breast cancer. All types of TC were seen, with papillary thyroid carcinoma (PC) being the most common (79%). Anaplastic, medullary, follicular (FC), malignant lymphoma and Hürthle cell cancer accounted for 5.4%, 5.3%, 4.3%, 3.6% and 0.9% respectively. The frequency of PC was very similar (16%) in each of the third, fourth and fifth decades. The relative frequency (RF) of different types of TC was highest for PC with a ratio of 18:1 between PC and FC, which could be the highest ever reported. There was a clearly progressive increase in the number of thyroid tumors referred between 1975 and 1989. Although this increase was evident for both sexes, it was more apparent for females. There was also a distinct increase ( P<0.01) in the RF of PC from 76% (1975 to 1980) to 85% (1986 to 1989) Fifteen-Year Period (1975 at the King Faisal Specialist Hospital and Research Centre. 1995; 15(6): 579-584 Differentiated thyroid cancer (DTC) is a relatively common malignancy with a marked international variation in the incidence of the disease. Limited data are available on the incidence and clinicopathological features of TC from the Middle East.1-23 Pertinent information regarding the demographic, epidemiological, clinical and pathological features of TC from Saudi Arabia is needed to determine the prognostic factors and to develop effective management strategies.Information on the geographical distribution of cancer has been of great value for generation of epidemiologic hypothesis and formulation of concepts for the etiology of cancer. Such information would also be valuable for making global comparisons. Until a population-based tumor registry is established in Saudi Arabia and the figures for TC made available, the only other recourse is to analyze the experience emanating from large referral centers. It is in this context that we have embarked on a study of 928 consecutive cases of thyroid tumors, observed over a 15-year period (1975 to 1989) at the King Faisal Specialist Hospital and Research Centre. The specific aims of this work were: 1) To analyze the demographic features of patients with TC seen at our institution since its inception in 1975. 2) To classify and determine the crude relative frequency (CRF) of different thyroid tumors seen at KFSH&RC between 1975 and. CRF is the proportion of a given type of cancer in relation to all cases in a clinical or pathological series. 3) To determine any possible trend in the CRF of different types of TC seen at our institution.
Patients and MethodsSince its inception in November 1975, we have had 1500 cases of thyroid tumors at KFSH&RC. However, this