Prognostic significance of tumor-associated lymphangiogenesis in malignant melanomas of the conjunctiva.

PURPOSE: To evaluate whether tumor-associated lymphangiogenesis contributes to prognosis of conjunctival malignant melanomas and to study its association with other tumor characteristics.
DESIGN: Nonrandomized, retrospective case series. PARTICIPANTS: A total of 109 consecutive patients with primary conjunctival malignant melanoma.
METHODS: Proliferating lymphatic vessels were identified immunohistochemically using lymphatic vascular endothelial hyaluronan receptor-1 and podoplanin as specific lymphatic endothelial markers and Ki-67 as proliferation marker. Baseline tumor characteristics included tumor location, tumor thickness, tumor diameter, tumor origin, and tumor growth pattern. Kaplan-Meier and Cox regression analyses of the risk of local recurrence, lymphatic spread, distant metastasis, and melanoma-related death were performed. MAIN OUTCOME MEASURES: Intratumoral lymphatic vascular density and its association with tumor characteristics and recurrence-free, lymphatic spread-free, distant metastasis-free, and melanoma-specific survival.
RESULTS: Intratumoral and peritumoral proliferating lymphatic vessels could be detected in all of the 109 conjunctival melanoma samples. High intratumoral lymphatic density was significantly associated with palpebral tumor location (P<0.001), greater tumor thickness (P<0.001), larger tumor diameter (P = 0.001), tumor origin de novo (P = 0.002), and nodular tumor growth pattern (P = 0.037). Patients with high intratumoral lymphatic density revealed significantly lower recurrence-free, lymphatic spread-free, distant metastasis-free, and melanoma-specific survival rates (P<0.001 for all). By multivariate Cox regression, factors predictive of local recurrence included palpebral tumor location (hazard ratio [HR] 2.66, P = 0.014), large tumor diameter (HR 5.48, P<0.001), and high intratumoral lymphatic density (HR 2.48, P = 0.043); factors predictive of lymphatic spread included palpebral tumor location (HR 4.13, P = 0.009), high tumor thickness (HR 12.17, P<0.001), and high intratumoral lymphatic density (HR 6.79, P = 0.019); factors predictive of distant metastasis included palpebral tumor location (HR 7.63, P<0.001), high tumor thickness (HR 8.60, P<0.001), large tumor diameter (HR 0.30, P = 0.029), and high intratumoral lymphatic density (HR 8.90, P = 0.047); and factors predictive of melanoma-related death included palpebral tumor location (HR 7.74, P<0.001), high tumor thickness (HR 10.88, P<0.001), large tumor diameter (HR 0.28, P = 0.018), and, with borderline significance, high intratumoral lymphatic density (HR 8.46, P = 0.052).
CONCLUSIONS: Tumor-associated lymphangiogenesis seems to be associated with an increased risk of local recurrence, lymphatic spread, distant metastasis, and melanoma-related death in patients with conjunctival malignant melanomas. FINANCIAL DISCLOSURE(S): The author(s) have no proprietary or commercial interest in any materials discussed in this article.