Merkel Cell Carcinoma: Value of Sentinel Lymph-Node Status and Adjuvant Radiation Therapy
Menée à partir de données portant sur 87 patients atteints d'un carcinome à cellules de Merkel traité par résection puis radiothérapie (durée médiane de suivi : 39 mois), cette étude évalue, en fonction du stade de la maladie, l'association entre une biopsie du ganglion sentinelle dont le résultat est négatif et la survie sans progression ou la survie globale des patients
Background : Sentinel lymph-node biopsy (SLNB) is a valuable tool to assess the regional lymph-node status in Merkel cell carcinoma (MCC). However, its prognostic value is still debated. This study was undertaken to assess SLNB usefulness for MCC management and to determine the impact of SLNB status on disease-free survival (DFS) and overall survival (OS) by comparing SLNB-positive v -negative patients according to demographic, clinical and treatment characteristics.
Patients and Methods : In this retrospective, multicenter observational study, SLNB was proposed to all patients referred for clinically N0 MCC. Treatment schedule consisted of wide-margin surgical resection of primary MCC followed by adjuvant radiation therapy (aRT) to the primary site and, for SLNB-positive patients, radical lymph-node dissection followed by regional aRT. Univariate and multivariate analyses determined factors associated with DFS and OS.
Results : Among 87 patients with successful SLNB, 21 (24.1%) were SLNB-positive. Median follow-up for the entire series was 39 months; respective 3-year DFS and OS rates were 73% and 81.4%. Univariate analysis (all patients) identified SLNB-negativity as being associated with prolonged OS (P=.013) and aRT (all sites considered) was associated with longer DFS (P=.004) and OS (P=.018). Multivariate analysis (all patients) retained SLNB status and aRT (all sites considered) as being associated with improved DFS (P=.014 and P=.0008) and OS (P=.0020 and P=.0019). Moreover, for SLNB-negative patients, tumor-bed irradiation was also significantly associated with prolonged DFS (P=.006) and OS (P=.014).
Conclusion(s) : The present study demonstrates that SLNB-negativity is a strong predictor of longer DFS and OS in stage I and II MCC patients. The similar benefit for aRT on tumor-bed observed in this study has to be confirmed by a prospective study. The results advocate for SLNB being considered to all MCC patients.
Annals of Oncology , résumé, 2016