Multifocality of papillary thyroid carcinoma as a risk factor for disease recurrence

Objectives: Tumor multifocality or bilaterality is associated with increased risk of papillary thyroid carcinoma (PTC) recurrence. However, its prognostic value in clinical outcomes remains controversial. This study aimed to evaluate the association of multifocality or bilaterality with recurrence and survival after total thyroidectomy. Methods: This was a retrospective study of 2390 consecutive patients with pathologically confirmed PTC who underwent total thyroidectomy. Multifocality and bilaterality were decided based on the final pathology results, that is, if there were two or more tumor foci and bilateral location, respectively. Primary outcomes were recurrence-free survival (RFS). Cox proportional hazards regression analyses were used to assess the associations of multifocality, bilaterality, and other clinicopathological factors with RFS. Results: Multifocal and bilateral PTC were found in 892 (37.3%) and 593 (24.8%) patients, respectively. Multivariate analyses showed that multifocality, lymphovascular invasion, N category, and number of positive lymph node ( > 5) were significant independent variables predictive of RFS (all P < 0.05). Multifocality was associated with adjusted hazard ratios for RFS of 1.93 (95% confidence interval = 1.33-2.80; P = 0.001). In a subset analysis, the prognostic value of multifocality was found to be significant in those patients with PTC > 1 cm, but not in papillary thyroid microcarcinoma. Conclusions: Tumor multifocality is an independent risk factor of PTC recurrence after total thyroidectomy. This indicate a more progressive state of disease, being included in risk stratification.