Prognostic factors and survival after recurrence in major salivary gland carcinomas: a multicenter study

Major salivary gland carcinomas (MSGCs) are rare, heterogeneous malignancies with high recurrence rates. Recurrent-metastatic (RM) MSGCs frequently represent a clinical challenge due to their unpredictable behavior and the absence of established prognostic markers for the disease course of relapsed disease.

This multicenter retrospective study, involving 10 tertiary centers worldwide, included patients affected by loco-regional and/or distant relapse after surgery with curative intent. The study aimed to analyze residual survival (recurrent-metastatic survival, RMS) and identify key prognostic factors to support personalized treatment strategies, especially for exclusive loco-regional and distant recurrences.

Among 212 patients, the median disease-free interval (DFI) after the initial treatment was 14 months, with a 1-year RMS of 58.1% (95% CI, 51.6-65.6%). Longer DFI (>30 months), adenoid cystic carcinoma histology, loco-regional recurrence rather than failure at distance, and absence of nodal metastasis (pN0) at initial diagnosis were significantly associated with a better residual overall survival. In patients with exclusive loco-regional recurrence, independent positive prognostic factors included DFI, salvage surgery, primary low-grade tumor, and lower pT classification. In contrast, for patients with exclusive distant metastasis, longer DFI (>30 months) and the type of intervention (metastasectomy for oligometastatic disease) were independent prognosticators.

Disease-free interval is a key prognostic factor for the residual overall survival after a recurrence event. Primary tumor characteristics were associated with survival outcomes in the loco-regional recurrent setting, but not if the recurrence is at distance. Whenever feasible, salvage surgery for loco-regional recurrence and metastasectomy for oligometastatic disease may be considered in highly selected patients.