Prognostic significance of thymidylate synthase (TS) expression in cutaneous malignant melanoma

Thymidylate synthase (TS) plays an essential role in the pathogenesis and development of cancer, and TS-targeting agents have been widely used against different types of cancers. However, it remains still unclear whether or not TS is expressed in malignant melanoma. We conducted the clinicopathological study to investigate the prognostic significance of TS expression in cutaneous malignant melanoma. Ninety-nine patients with surgically resected cutaneous malignant melanoma were assessed. Tumor sections were stained by immunohistochemistry for TS, Ki-67, and microvessel density (MVD) determined by CD34. TS was positively expressed in 26% (26 out of 99). The expression of TS was significantly associated with T factor, cell proliferation (Ki-67) and MVD (CD34). By Spearman's rank test, TS expression was significantly correlated with Ki67 and CD34. By univariate analysis, ulceration, disease stage, TS, Ki-67 and CD34 had a significant relationship with survival. Multivariate analysis confirmed that TS was an independent prognostic factor for poor prognosis of cutaneous malignant melanoma. The positive expression of TS could be a useful marker for predicting poor prognosis in patients with cutaneous malignant melanoma, and TS-targeting agents may be worth trying for the treatment of this dismal disease.