Disease Free Survival of Well Differentiated Thyroid Cancer: 20 years Experience at a tertiary care center in Lebanon

Background: Thyroid cancer is the most common endocrine malignancy. Although relatively common, to date, there is no study about its prognosis in Lebanon. The objectives of this study were to determine the disease free survival, the recurrence rate and possible predictors of recurrence, as well as the rate of post thyroidectomy complications among patients with differentiated thyroid cancer who received treatment at the American University of Beirut Medical Center. Methods and Findings: retrospective observational study of 480 cases of differentiated thyroid cancer who underwent thyroidectomy between January 1995 and June 2014. The mean age was 42±14 years. 74.4% were females. The mean tumor size was 1.9 cm±1.4. Papillary type was predominant (91%). Males had more extra-glandular extension than females (24.8% versus 10.9% respectively, p=0.001), more lymph node involvement (69.7% versus 52.9% respectively, p=0.017) and more vascular invasion (28.1% versus 14.9%, p=0.007). Around 70% of patients had at least one follow up visit after the surgery; among those, the median follow up duration was 4 years (1month-19years). At last follow-up visit, 78.7% were disease free, 14.9% had residual disease and only 6.3% had recurrent disease. By multivariate analysis, age greater than 45 years was the only independent predictor of persistence or recurrence (p=0.03) whereas both age below 45 years and lack of vascular invasion were significant predictors of disease free survival (p=0.001 and p=0.019 respectively). Conclusion: Differentiated thyroid cancer has an overall good prognosis in this cohort of Lebanese patients. Young age and lack of vascular invasion are the most important predictors of disease free survival.   Key words: Differentiated thyroid cancer: disease free survival, prognostic factors, recurrence