**4. Conclusions**

Nodal metastasis is common in differentiated thyroid cancers and its pattern of spread is well recognized. Despite improvements in technology, imaging has limited sensitivity to detect nodal metastasis before initial surgery or when disease recurs. Occult nodal metastasis is very common and may explain persistent disease or early recurrence. However, distinction between macroscopic and microscopic nodal metastasis and their prognostic implications must be made clear.

Many unanswered questions regarding management of nodal metastasis remain. Prophylactic central neck dissection may remove occult nodal metastasis but its impact on survival lacks high-quality evidence support and is best reserved for selected patients by experts. Sentinel nodal biopsy is an attractive concept but further evidence from research is required. Even when nodal metastasis is detected before the initial surgery, the optimal extent of therapeutic neck dissection remains debated. When disease ultimately recurs, the decision to operate is complex, taking

into consideration the increased rate of morbidities in re-operative surgeries. Active surveillance may be best for low-volume recurrent disease while other nonoperative treatments can be considered in patients not suitable for surgery.
