Objective : To report prognostic factors of localized sinonasal mucosal melanoma (SNMM) treated in a multi-institutional setting.

Design : Retrospective review

Setting : French medical institutions.

Patients : A total of 142 patients with non-metastatic SNMM treated from 1980 through 2008 with surgery alone or surgery and postoperative radiotherapy.

Results :
On univariate analysis, only T stage was significant(p=0.001) as a prognostic factor of 5-years relapse free survival : 42.8% for T1-2 vs 12.1% for T3-4. Locoregional control was significantly (p=0.018) improved by postoperative radiotherapy : the locoregional recurrence rate was 55.1% with surgery alone vs 33.2% with postoperative radiotherapy. The 5-years metastatic recurrence rate was significantly higher for T3-4 tumors (43.1% vs 21.6% for T1-2 tumors; p=0.016) and for sinus tumors ( 41.7% vs 21.6% for nasal tumors; p=0.006).
On multivariate analysis, T stage was found as an independent risk factor of relapse free survival (HR = 2.36 ; p=0.003) and locoregional control (HR = 2.02 ; p=0.048). The hazard ratio of metastatic spreading of sinus tumors was 2.5 (p=0.049) when compared to nasal tumors. Sinusal location and advanced T stage were both siginificantly associated to poorer 5-years overall survival.

Conclusion :
This study shows that there is a clear difference between sinusal and nasal mucosal melanomas : sinusal tumors are associated to more frequent metastatic spreading and poorer prognosis.
It also shows that AJCC T stage is still valid as a prognostic factor of relapse free survival, locoregional survival and overall survival.