Thyroid cancer is the most frequent endocrine malignancy. In Saudi Arabia thyroid carcinomas accounted for 5% of all newly diagnosed cancers. This cancer ranked 14th in males and 2nd in females.1,2 Although thyroid nodules are common, differentiated and undifferentiated thyroid carcinomas are relatively rare. Clinically detectable thyroid carcinomas constituted less than 1% of all cancers.3 The median age at diagnosis was 45 to 50 years. The assessment of thyroid nodules has also evolved, with percutaneous fine needle aspiration cytology (FNAC) becoming the most important tool of investigation.4 Papillary and follicular thyroid carcinomas are among the most curable cancers. However for several decades the management of different thyroid cancer has been controversial. For majority of patients, standard initial management consists of thyroidectomy followed by radioiodine ablation.5 However there is a great controversy regarding the ablative dose of iodine 131 (I 131) and its indication; other conventional modes of neoplastic treatment; chemotherapy with external beam irradiation have much poorer results. The overall survival rate at 10 years for middle age adults with thyroid carcinoma is approximately 80-95%. Five to 20% of patients have distant metastasis. The prognostic indicators of recurrent disease and death are the age at time of diagnosis, histopathology type of thyroid cancer. The relationship between these factors remains incompletely defined. However Coburn and Wanbeo6 concluded that the prognostic importance of age in thyroid cancer may be due to the great prevalence of pathological risk factors in older patients. The aim of this retrospective study is to estimate the incidence of thyroid cancer in

King Abdul Aziz University Hospital (KAUH) is a teaching government hospital providing health care to a multinational population of mixed socioeconomic strata. A total of 120 thyroidectomies were performed in surgical department in the period between January 2001 and December 2003. All patients presented with single nodule or multinodular goitre were included in the study. The medical notes were reviewed for age, sex, nationality, radiation history, family history of thyroid disease, clinical presentation, physical examination of neck included goitre and cervical lymph nodes. The data included thyroid function test, thyroid scan which was done routinely in most of the patients to confirm the solitary nature of nodule or otherwise. Results of fine needle aspiration of thyroid nodule or any palpable cervical nodes at presentation before surgery as well frozen section results if done before thyroidectomy. In attempts to identify the possible correlation between the age of the patients at presentation and other risk factors, the study group was analyzed in 4 age group. Group A included patients younger than 30 years, group B included those ranging between 30-45 years. Group C included those between 45-60 years and Group D included patients older than 60 years. Almost all patients had total thyroidectomy included. Those patients, who were found to have conservative surgery were referred for completion of near total thyroidectomy. Six week after surgery, when Thyrotrophin (TSH) level > 30 iu/ml, diagnostic whole body scan was performed. Thereafter radio iodine 131 therapeutic doses was given by the nuclear medicine physician. 100-200 mCi for remnant ablation, 200-300 mCi for lymph nodes metastases or distant metastases. After radio iodine therapy patients with gross residual disease received external beam radiotherapy (whole neck irradiation of total dose of 50-60 Gy over 4-6 weeks). All patients were put on a suppressive dose of L- thyroxin and kept under regular follow up for TNM (tumour, node, metastases) system recommendation7,8

Then 6-12 months after first dose radio iodine therapy. Patients were followed in nuclear medicine clinic where second whole body scan in each patient was performed. If there were persistent abnormal radio iodine uptake, a 2nd or 3rd dose of 131 was given.

Results were expressed as a mean ± SD (standard division). Results were considered significant if the p value is less than 0.005. All analyses were performed with excel programme.

Out of total 120 thyroidectomies performed during the three years period between January 2001 and December 2003 at King Abdulaziz University Hospital, 45 (37.5%) patients with a histopathologically confirmed diagnosis of thyroid cancer were included in the study. Nineteen (42.2%) were Saudi, where various other nationals comprised 26 (57.8%) cases with Saudi : Expatriate ratio of 0.7:1. Twenty four (53.3%) were males and 21 (46.7%) were females, with male to female ratio of 1.1:1. Mean age of all patients was 40.5 ± 14.8 years. Mean age of females was 38.4 ± 11.64 years and of males was 42.5 ± 16.9 years with p value 0.004. (Table 1) None of the patients in this study gave history of radiation exposure in the past. Family history of goitre and thyroid disease was available in 10 (22.2%) cases, however there was no family history of thyroid cancer in our patients.

Table 1 : Age, sex, and nationality of 45 patients with thyroid cancer
Variable	No.	%
Sex	45
Male	24	53.3%
Females	21	46.7%
Male : Female ratio	1.1:1
Nationality
Saudi	19	42.2%
Expatriate	26	57.8%
Saudi : expatriate ratio	0.7:1
Age (mean ± SD)	40 ± 14.9
<30 years	15	33.3%
30-45	17	37.8%
45-60	7	15.6%
³ 60	6	13.3
Total	45	100%

Thyroid cancer is regarded as the most frequent endocrine malignancy with a variable geographic and ethnic incidence around the world.1,16 The overall incidence is reported to be increasing world wide with changing characteristics. In most series, papillary carcinoma is the predominant cancer, whereas follicular and anaplastic tumours are becoming less frequent. Radiation exposure17 and endemic goitre have been suggested as strong aetiological factors. In Kingdom of Saudi Arabia, thyroid carcinomas have accounted for 5% of all newly diagnosed cancers and tanked 14th in males and 2nd in females.2 In our series papillary carcinoma was the commonest variety (82.2%) followed by ana-plastic (6.7%) and follicular cancer (4.4%) of all thyroid malignancies. Incidence of follicular thyroid cancer in our study is much lower than what is reported from other reports of Saudi Arabia15 or other geographical areas.18 Medullary carcinoma constituted 6.7% of all thyroid malignancies in this series. This is comparable to most other reports. It is not known whether cases of medullary carcinoma in this series are familial or sporadic cases as most of thes patients were lost to follow up after total thyroidectomy.19

No known aetiological factors (radiation exposure, endemic goitre, cancer thyroid among family) could be confirmed in any of the patients in this study. Male preponderance in this study was different than various local and international reports where thyroid cancer was commoner in females. This could be related to the fact that most of our patients were expatriates as King Abdul Aziz University Hospital is a teaching governmental hospital providing health care to Saudis and expatriates population equally.

The mean age was 40.5 years which was younger than 45-48 years old reported from other international studies; however it is similar to studies reported from Saudi Arabia.20,21 This reflects the changing clinic epidemiological behaviour of the disease in different parts of his world.22 The mean age of females was 38.4 years which was younger than males 42.5 years and is similar to various other reports.

Prognostic factors associated with differential thyroid cancer included the age of the patient at the time of diagnosis, tumour size, extra thyroid extension, nodal status, distant metastases, operative procedures, sex and histopathology. Multivariate analysis showed that distant metastases, age, tumour size were the most significant prognostic factors.23,24 However Coburn and Wanebo6 suggested that the prognostic importance of age of thyroid cancer may be due to the greater prevalence of pathological factors in older patients. In our study there was statistically significant association between older age and pathology of cancer, follicular and anaplastic carcinoma was commoner in age group older than 45 years. Higher incidence of lymph nodes and distant metastases were encountered in older patients.25,26

Thyroid cancer presents most frequently as solitary thyroid nodule. This was not the case on patients in this series, where 30 (66.7%) presented as multinodular goitre. This was probably due to the late presentation of these patients.27

Fine needle aspiration cytology of thyroid is now considered as an important diagnostic aid in the investigations of solitary nodules and goitre. This is particularly useful in screening and selection of patients presenting with solitary or mulinodular goitre. In the current study FNA confirmed the diagnosis of thyroid carcinoma in 76% of our patients, so that they were subjected directly to near total thyroidectomy. The positive FNA in range of 70-79% is similar to what is described in the local and international series.28 The post-operative treatment of patients with well differential thyroid cancer, particularly relating to radioiodine therapy is controversial.29 The dose of I131 for ablation is not standardized. Some recommend low dose ablation with less than 30 mCi given as out patient with the successful ablation rate ranging between 27% and 83%. With this method repeated doses are usually required for ablation. Higher ablative doses ranging from 100-200 mCi should be used for older high risk patients particularly known to have incomplete resection of the primary tumour an invasive ablative rate of 87%. Doses may be calculated using one of the several dosimetric approaches or standard fixed doses may be used forall patients.30,31 In current study, the ablative dose used by nuclear medicine was relatively higher than standard doses especially in recurrence of thyroid malignancy or metastases. The nuclear medicine physicians’ policy that this therapeutic approach might be effective in improving prognosis and survival of such patients.32

The current study as many others, concludes that thyroid cancer is one of the important endocrine cancer with increasing incidence worldwide with changing characteristics especially in different ethnic groups like in our series. Although little doubt exists regarding the role of FNA biopsy in pre- operative diagnosis of thyroid cancer, each step in the subsequent management give rise to controversy and debate regarding extent of primary surgical resection, the need for extensive regional lymph node dissection and the role of external irradiation and radiotherapy. We recommend that thyroid cancer patients should be treated by a team of endocrinologist, pathologist, experienced thyroid surgeon, nuclear medicine and external radiotherapy physician to achieve a good care and prognosis of patients.