Differentiated (papillary / follicular) thyroid cancer (TC) in general has indolent characters and a relatively ‘benign’ biological behavior.
In some cases, however, this common neoplasm has certain clinicopathological characters which may indicate a dire prognosis.
Factors associated with a high risk for disease recurrence (both locoregional [in the neck] as well as distant metastases) and unfavorable outcome include:
- Distant metastasis at the time of diagnosis
- Tumor size > 4 cm
- Gross extrathyroidal extension (macroscopic invasion of adjacent tissues / structures)
- Incomplete surgical excision
- Extensive vascular invasion
- Presence of positive node > 3 cm
- Extranodal tumor extension positive with > 3 lymph nodes involved
- Age > 55 years
- Follicular TC (as well as medullary TC)- metastasizes to distant sites more commonly than papillary thyroid cancer
- Aggressive histological variants of differentiated TC (such as tall/columnar variant of papillary thyroid cancer and insular/trabecular variant of follicular TC)
- Presence of BRAF-V600 mutation (should be evaluated in the context of other standard clinic-pathological risk factors)
The presence of these risk factors should be taken into consideration in the decision-making process regarding postoperative management and follow-up strategy.
J Clin Endocrinol Metab 2017; 102: 1254
Endocrine J 2019; 66: 127
Thyroid 2016; 26: 1