Prognostic significance of MGMT gene promoter methylation in differently treated metastatic melanomas.

Aims: The methylation status of the MGMT gene promoter, considered of prognostic significance by enhancing chemosensitivity to alkylating drugs in gliomas and melanomas, was evaluated in a series of primary melanomas and metastases of patients treated with different therapies, to identify any correlation with the patients' outcome or response to different therapeutic regimens.

Methods: Twenty-nine primary melanomas and 74 metastases, collected from 52 patients, were assessed for MGMT gene promoter methylation using a standard methylation specific PCR-based method. All materials were formalin fixed and paraffin embedded.

Results: One of 29 primary melanomas (3.4%) and 22 of 74 metastases (29.7%) showed MGMT gene promoter methylation. MGMT methylation was more frequent in visceral (17/40, 42.5%) than in cutaneous/lymph node metastases (5/34, 14.7%) (p = 0.019). Both disease free (DFS) and overall survival (OS) were significantly longer in patients with methylated metastases (p = 0.009 and p = 0.007, respectively). No correlations were found among methylation, therapeutic regimens and DFS or OS.

Conclusions: MGMT methylation appears to be a late event in the biological history of melanoma and is more frequently seen in visceral metastases. The MGMT gene promoter methylation in metastatic disease is associated with longer survival, irrespective of therapy. Thus it could be considered a prognostic factor in metastatic melanoma.