Retrospective analysis of clinical and cardiovascular risk factors in patients with differentiated thyroid cancer

Differentiated thyroid cancers account for the majority of thyroid cancers deriving from thyroid follicular epithelial cells. Common types of differentiated thyroid cancers comprise papillary cancers (85% of cases), follicular cancers (10%) and Hurthle (oxyphilic) cell carcinomas (3%). Our study aimed to conduct a retrospective analysis of patients diagnosed with differentiated thyroid cancer, as well as cardiovascular risk identification and evaluation of compliance with national and international treatment guidelines. This retrospective study included a sample of 172 patients with differentiated thyroid cancer, who were followed up for at least one year at Akdeniz University Medical Faculty Hospital, Department of Endocrinology and Metabolic Diseases between 1984 and 2013. The following parameters found in the hospital records and patient files were included in the analyses: patient's age at diagnosis, gender, follow-up period, pathological characteristics (tumor type, subtype, maximum tumor size, vascular invasion, lymph node metastases at diagnosis and during follow-up, extrathyroidal invasion, distant metastases at diagnosis and during follow-up, multicentricity), surgical method, surgical complications (hypoparathyroidism and/or vocal cord paralysis for at least 1 year), RAI therapy dose, iodine-131 whole body scan performed at 7 days and 9-12 months after the treatment, neck ultrasonography during follow-up, stimulated thyroglobulin and anti-thyroglobulin values, suppressed TSH thyroglobulin and anti-thyroglobulin levels after RAI therapy, Fasting Blood Sugar, Creatinine, T. cholesterol, LDL-C, HDL-C, triglycerides, ALT, albumin, calcium, phosphorus, TSH, fT4 levels, cardiovascular diseases and risk factors [diabetes mellitus, hypertension, coronary heart disease, dyslipidemia, cerebrovascular event and peripheral artery disease, family history of early CVD (for first degree relatives, ˂55 years in men and ˂65 years in women), smoking, alcohol use], atrial fibrillation. Patients were categorized based on their AJCC/UICC TNM staging and risk scores for ATA risk stratification. Of the patients included in the study, 141 patients (83.4%) had papillary thyroid cancer (PTC), while 28 patients (16.6%) had follicular thyroid cancer (FTC). 155 of the patients were female and 14 were male, with a female: male ratio of 11.3. The evaluation of patients based on TNM staging showed that 81.7% of the patients had Stage I disease, 5.3% Stage II, 10.6% Stage III, and 2.4% unknown stage. Based on ATA (American Thyroid Association) risk stratification, 72% of the patients were categorized as low-risk group, 21% intermediate-risk group, while 7% had unknown risk status. 87.5% of the patients in the low-risk group and 100% of the patients in the intermediate-risk group had received RAI therapy (p:0,02). The mean age at diagnosis with FTC was higher than PTC (p:0,02). Average tumor diameter was 1.39±1.24 cm in PTC and 2.33±1.19 cm in FTC, which was significantly higher in FTC (p:0,03). Vascular invasion was more prevalent in FTC (p:0,01), while extrathyroidal invasion was more prevalent in PTC (p:0,046). Only 3 patients had metastatic disease at diagnosis. Of the remaining 169 patients, 13 (7.7%) had recurrence. 12 (92.3%) of these patients had PTC, and only 1 of them had FTC (7.7%). The mean age at diagnosis was higher in the recurrence group than in the remission group (p:0,02). The mean tumor diameter was significantly greater in the recurrence group (p:0,03), with 2.17±2.03 cm in the recurrence group and 1.31±1.12 cm in the remission group. Of the 141 patients with papillary thyroid cancer, 12 (8.5%) developed recurrence, while only 1 of the 28 patients with follicular thyroid cancer (3.6%) had recurrences (p:0,001). Recurrence rate was higher in patients with extrathyroidal invasion and lymph node metastasis at diagnosis (p:0,000). Multifocality, sex, vascular invasion, and surgery method were found to have no significant effect on recurrence. Surgical complications were more prevalent in patients undergoing neck dissection surgery (p=0.003). No significant difference was found between the complication rates of total thyroidectomy and completion thyroidectomy. Hypoparathyroidism was more prevalent in the patients receiving neck dissection (p:0,002) and those receiving completion thyroidectomy (p:0,0001), whereas no significant difference between the groups in terms of vocal cord paralysis. Of the patients 21.5% had DM, 30.2% HT, 4.7% CHD, 1.2% CVO, 26.2% dyslipidemia, and 15.1% family history of early CVD. Only 3 (1.7%) patients had developed atrial fibrillation. All patients with AF were women over the age of 60. Cardiovascular events were more prevalent in patients with AF, as compared to those with no AF history (p:0,02). T. Cholesterol and LDL-cholesterol levels were significantly lower in the recurrence group than in the remission group (p:0,02). Incidence of cardiovascular events was higher in patients with dyslipidemia (p:0,02). In conclusion, our study found that factors such as histological type, age at diagnosis, tumor size, extrathyroidal invasion and lymph node metastasis at diagnosis increased the risk of recurrence. However, further studies with larger sample sizes are needed to elucidate the role of these factors and other possible risks. Finally, we suggest that patients with differentiated thyroid cancer should be closely monitored for cardiovascular risk factors, and TSH suppression therapy should be administered after careful evaluation based on the patient's risk category and age, while adopting a more selective approach to the use of RAI therapy based on the patient's risk category