Recurrent thyroid cancers have more peritumoural lymphatic vasculature than nonrecurrent thyroid cancers

BACKGROUND: The goal of the study was to evaluate angiogenesis and lymphangiogenesis in differentiated thyroid cancer and recurrences. METHODS: Twenty-seven patients with recurrent differentiated thyroid cancer (20 papillary and seven follicular thyroid carcinomas) and 24 nonrecurrent thyroid cancers were included in this study. Additionally, 24 thyroid adenomas were included as benign controls. All thyroid cancer recurrences were operatively managed, and local recurrences in cervical lymph nodes or cervical soft tissue were histologically confirmed. Altogether, a total of 108 samples were evaluated using CD31 and D2-40 immunohistochemical staining and microscopy. RESULTS: As measured in primary tumours, the median density of CD31-positive vascular structures was 327 vessels (v)/mm(2) for recurrent cancers, 362 v/mm(2) for nonrecurrent cancers and 484 v/mm(2) for thyroid adenomas (P = 0·017). Among the subgroups, the lowest median vascular density of 316 v/mm(2) was found in recurrent papillary cancers and the highest vascular density of 604 v/mm(2) was observed in nonrecurrent follicular cancers (P = 0·018). The median density of D2-40-positive peritumoural lymphatic vessels was 101/mm(2) in recurrent cancers, 56·1/mm(2) in nonrecurrent cancers and 53·9/mm(2) for adenomas (P = 0·015). In the subgroups, peritumoural lymphatic vascular density was 102 v/mm(2) in recurrent papillary cancers and 56·0 v/mm(2) in nonrecurrent papillary cancers (P = 0·044). CONCLUSIONS: Recurrent thyroid cancers expressed less intratumoural microvessels than thyroid adenomas. A high density of peritumoural lymphatic vessels was found in recurrent papillary cancers. High blood vessel density may be a marker for less aggressive tumours, while high peritumoural lymphatic vasculature is a marker for more aggressive and recurrence-prone tumours.