Detection of melanoma cells in sentinel lymph nodes by reverse transcriptase-polymerase chain reaction: Prognostic significance

Background: Recently reverse transcriptase-polymerase chain reaction (RT-PCR) has been proposed as a new sensitive method for the detection of submicroscopic melanoma nodal metastases. Sentinel lymph node (SLN) status is considered the most important prognostic factor for melanoma patients. Thus, in recent years, melanoma research has been focused on identifying new molecular markers of micrometastases. Methods: In this study, 129 SLNs were collected and analyzed by RT-PCR for tyrosinase and melanoma inhibitory activity (MIA) messenger RNA (mRNA) expression. Results from PCR analysis were then compared with those obtained by hematoxylin and eosin and immunohistochemistry and related to progression of disease. Results: MIA gene expression was positive by RT-PCR in 27% of the tyrosinase-positive SLNs. When the correlation between tyrosinase and/or MIA mRNA expression and disease-free survival was evaluated by the Kaplan-Meier exact test, there was a statistically significant correlation between simultaneous tyrosinase and MIA gene expression in SLNs and progression of disease. Conclusions: RT-PCR analysis for both MIA and tyrosinase mRNA may identify a subset of melanoma patients with a worse prognosis whom the routine methods, such as histology and immunohistochemistry, fail to identify because of the poor sensitivity of these methods.