PURPOSE/OBJECTIVE(S): Salivary duct carcinomas (SDC) make up < 2% of salivary duct tumors but are very aggressive with a low 5-year survival rate of 35%. This series reports long term outcomes of patients with SDC treated at a single institution. MATERIALS/METHODS: Patients ≥18 years with histological confirmation of SDC treated with curative intent from 1961-2018 were included in this analysis. Patients were excluded if treatment was palliative intent (N = 14), and if staging (N = 4) or locoregional control (LRC) status (N = 7) was not recorded. 89 patients (74% male) met criteria for inclusion. Median age was 66 years (range: 32 - 89). AJCC 8 staging of patients were as follows: 13% (I), 6% (II), 12% (III), 62% (IVa), and 7% (IVb). 67% of patients were lymph node positive. Kaplan Meier analyses were used to estimate LRC and OS rates. Bivariate regression analyses using disease and treatment characteristics (i.e., perineural invasion (PNI), extracapsular extension (EE), vascular invasion (VI), CN VII sacrifice, extraparenchymal involvement (EI)) for prediction of LRC and OS were performed. RESULTS: Median follow-up was 48.5 months (0.4-343 mo). Most patients were treated with combined modality therapy; 82% (n = 73) undergoing curative surgery followed by adjuvant radiotherapy (RT) with (26%, n = 23) or without (56%, n = 50) concurrent chemo while 4.5% (n = 4) were treated with definitive RT; 2.3% (n = 2) receiving concurrent chemo. 13.5% (n = 12) were treated with surgery alone. Crude post-treatment LRC after surgery alone, surgery followed by adjuvant RT, and definitive RT alone were 66.7, 78.1 and 0% (P = 0.002), respectively. The odds of achieving LRC were diminished with incidence of VI (odds ratio (OR) = 0.07, P = 0.02), EI (OR = 0.3, P = 0.03), and T3/T4 staging (OR = 0.3, P = 0.03). Chemotherapy did not influence LRC. The occurrence of distant metastases was associated with PNI (OR = 5, P = 0.003) and EI (OR = 2.6, P = 0.03). EI status was also associated with a shorter time to recurrence (26 vs 17.3 mo, P = 0.04). Median overall survival (OS) was 55.3 months (41.7-81.7 95% CI) with 82% surviving at 2 years, 47% at 5 years, and 28% at 10 years. Failure to achieve LRC (81.7 vs 36 mo, P < 0.001), distant metastases (108.5 vs 41.7 mo, P < 0.001), VI (86.2 vs 46.8 mo, P = 0.046), T3/T4 staging (125.8 vs 48.8 mo, P = 0.02), PNI (88.1 vs 48.8 mo, P = 0.03), and EI (108.5 vs 47.3 mo, P = 0.004) were found to significantly reduce median OS. CONCLUSION: SDC is an aggressive tumor that requires a multimodality treatment approach. Patients analyzed here had a 5-year survival greater than what is typically reported for SDC (47 vs. 35%). Definitive radiotherapy was less likely to control gross disease and should be reserved for the adjuvant setting if surgery is an option. We identified incidence of extraparenchymal involvement, perineural and vascular invasion as negative prognostic indicators of disease control and survival.
|Original language||English (US)|
|Journal||International journal of radiation oncology, biology, physics|
|State||Published - Nov 1 2021|
ASJC Scopus subject areas
- Radiology Nuclear Medicine and imaging
- Cancer Research