Risk Factors Associated with Disease Recurrence among Patients with Low-Risk Papillary Thyroid Cancer Treated at the University of the Philippines-Philippine General Hospital

BACKGROUND: The management of papillary thyroid carcinoma (PTC) in high-risk patients is well-standardized. However, this is not the case for low-risk patients. Filipinos show a high incidence of recurrence of thyroid cancer. Thus, the identification of risk factors for recurrence in this population could potentially identify individuals for whom radioactive iodine (RAI) therapy might be beneficial. METHODS: We reviewed the medical records of adult Filipinos with low-risk PTC who underwent near-total or total thyroidectomy at the University of the Philippines-Philippine General Hospital. Multivariate logistic regression analysis was used to determine risk factors for recurrence. RESULTS: Recurrence was documented in 51/145 of patients (35.17%) included in this study. Possible risk factors such as age, sex, family history, smoking history, tumor size, multifocality, prophylactic lymph node dissection, initial thyroglobulin (Tg) level, initial anti-thyroglobulin (anti-Tg) antibody concentration, suppression of thyroid stimulating hormone production, and RAI therapy were analyzed. Multivariate analysis revealed that a tumor diameter 2 to 4 cm (odds ratio [OR], 9.17; 95% confidence interval [CI], 1.62 to 51.88; P=0.012), a tumor diameter >4 cm (OR, 16.46; 95% CI, 1.14 to 237.31; P=0.04), and a family history of PTC (OR, 67.27; 95% CI, 2.03 to 2228.96; P=0.018) were significant predictors of recurrence. In addition, RAI therapy (OR, 0.026; 95% CI, 0.01 to 0.023; P≤0.005), an initial Tg level ≤2 ng/mL (OR, 0.049; 95% CI, 0.01 to 0.23; P≤0.005), and an anti-Tg antibody level ≤50 U/mL (OR, 0.087; 95% CI, 0.011 to 0.67; P=0.019) were significant protective factors. CONCLUSION: A tumor diameter ≥2 cm and a family history of PTC are significant predictors of recurrence. RAI therapy and low initial titers of Tg and anti-Tg antibody are significant protective factors against disease recurrence among low-risk PTC patients.