Prognostic impact of tumour burden measured by quantitative real-time PCR from sentinel lymph nodes of melanoma patients: data from 10-year follow-up.

BACKGROUND: Sentinel node (SN) biopsy is regarded as standard of care for patients (pts) with cutaneous melanoma ≥1.0 mm of thickness. In the recent AJCC classification, findings in the SN are simply classified as positive or negative. In our analyses, we were interested whether quantitative real-time PCR (qRT-PCR) is able to predict disease-free survival (DFS) and overall survival (OS) depending on tumour burden in the SN.

METHODS: One hundred and forty-five pts were analysed using qRT-PCR for tyrosinase. Results were analysed using accelerated failure time survival model and cox proportional hazards models using the R statistics framework.

RESULTS: Forty-one pts (28%) were positive according to qRT-PCR. In total, 12 of 41 pts showed tumour deposits in the SN using S100 and/or HMB-45-labelled immunohistochemistry as well. One patient had micrometastases detected by immunohistochemistry staining but failed in the qRT-PCR. After 10 years of follow-up, 34 patients recurred and 27 patients died. Significant differences for DFS and OS were detected for sex, increasing tumour thickness, ulceration of the primary tumour, and metastatic spread in the SN determined by histology as well as qRT-PCR.

CONCLUSION: Quantitative analyses showed a logarithmic correlation between tumour burden and prognosis. However, as multivariate analyses reveal qRT-PCR was not superior compared to classical histology or immunohistology.