Cyclooxygenase-2 Overexpression and its Association with Histopathological Features of Human Malignant Melanoma

Melanoma is one of the most common types of skin cancer with an annually increasing mortality rate. Cyclooxygenase-2 (COX-2) plays an imperative role as a cancer biomarker in the biosynthesis of prostaglandin and thromboxane during inflammatory reactions. Its overexpression has been demonstrated in various cancer types, including melanoma. However, its clinicopathological association with melanoma is controversial. We aimed to immunohistochemically evaluate COX-2 expression in malignant melanoma (MM) tumors.

In this cross-sectional retrospective study, blocks from patients with MM who were referred to Rasool-Akram and Razi hospitals between 2011 and 2020 were collected and immunohistochemically evaluated using COX-2 antibody. The intensity and percentage of COX-2 expression was determined in tumoral tissues, and its association with clinical and histological features of patients were evaluated.

A total of 39 patients diagnosed with MM were included in this study, of whom 20 (51.3%) were male and 19 (48.7%) were female, with an average age of 57.28 ± 14.37 (range 14-87 years). The most common histological subtypes were acral melanoma (30.8%) and nodular melanoma (20.5%). The most common locations of tumor involvement were the lower (33.3%) and upper limbs (23.1%). Ulcers and vascular-lymphatic invasion were observed in 33.3% and 5.1% of cases, respectively. 38.5% of tumors were in level IV according to Clark's level. Elastosis was present in 13% of samples. Approximately 87% of MM samples showed COX-2 expression, 61.5% of which were strong. There was a significant association between COX-2 expression and tumor location (P = .04).

Our findings highlight that the COX-2 protein is considerably expressed in MM tumors. Therefore, therapeutic strategies with the aim of targeting COX-2 might be considered in the prevention or treatment of MM. However, it remains to be explored whether COX-2 might be a prognostic marker of MM.