The clinical importance of multifocality on tumor recurrence in papillary thyroid carcinoma

Although the origin of the multifocality of papillary thyroid carcinoma (PTC) is unclear, it is not unusual and has not been considered as an independent prognostic factor from several tumor staging systems. This study aims to evaluate whether the presence of multifocality is associated with PTC recurrence.

We reviewed retrospectively detailed histological reports of PTC patients who underwent thyroidectomy from January 2000 through December 2010 at a single institution. We assessed the relationship between multifocality and other possible prognostic factors using binary logistic regression analysis. We compared recurrence by the Kaplan-Meier method (the log-rank test). We analyzed a prognostic factor for recurrence using Cox's proportional hazard model (the stepwise forward method).

We enrolled a total of 434 PTC patients (380 women and 54 men; mean age, 48 years). The median follow-up period was 10.2 years. Of all PTC patients enrolled, 135 patients (31%) had multifocal PTC. There was a significant association between multifocality and cervical lymph node (CLN) metastasis (P=0.01). Multivariate analyses showed a significant association between multifocality and CLN metastasis (P<0.001). Multifocal PTC patients had higher CLN metastasis and tumor recurrence than those with single PTC. There was a significant association between multifocality and tumor recurrence (P=0.03 by log-rank test), but it disappeared in multivariate analysis.

Multifocality of PTC might be related to CLN metastasis and tumor recurrence.