Background
Retrospective cohort, Dutch Head and Neck Oncology Cooperative Group (NWHHT). N=538, malignant salivary gland tumors. Sites: parotid 59%, submandibular 14%, oral cavity 23%. Analyzed role of postoperative and primary (definitive) RT, prognostic factors, and dose-response.
Interventions and follow up
Treatment: postoperative RT (PORT) vs surgery alone, and primary (definitive) RT for unresectable disease; multicenter retrospective analysis of major salivary gland tumors
Primary endpoint: local control, regional control, and RT dose-response
mFollow up: long-term (NR)
Primary endpoint: local control, regional control, and RT dose-response
mFollow up: long-term (NR)
Results
10-yr local control (PORT vs surgery alone), T3–4: 84% vs 18%
Close margins: 95% vs 55%
Incomplete resection: 82% vs 44%
Bone invasion: 86% vs 54%
Perineural invasion: 88% vs 60%
Regional control (pN+): 86% (PORT) vs 62% (surgery alone)
Local control vs surgery-to-RT interval: not correlated
Primary RT dose response: 5-yr local control 50% at 66–70 Gy
Close margins: 95% vs 55%
Incomplete resection: 82% vs 44%
Bone invasion: 86% vs 54%
Perineural invasion: 88% vs 60%
Regional control (pN+): 86% (PORT) vs 62% (surgery alone)
Local control vs surgery-to-RT interval: not correlated
Primary RT dose response: 5-yr local control 50% at 66–70 Gy
Adverse events
Toxicity grading: not formally graded in this retrospective series
Expected late effects: xerostomia and late fibrosis with high-dose PORT
Treatment-related mortality: NR
Expected late effects: xerostomia and late fibrosis with high-dose PORT
Treatment-related mortality: NR
Conclusions
Postoperative RT with ≥60 Gy significantly improved local and regional control for T3–4 salivary gland carcinomas, incomplete/close resections, bone invasion, and perineural invasion. Elective neck RT ≥46 Gy is indicated for high-risk primaries; ≥66 Gy advisable for unresectable disease.
Key Limitations
Retrospective, non-randomized with selection bias (PORT given to higher-risk disease yet still better controlled); heterogeneous histologies/sites; toxicity not formally graded; pre-IMRT era.
Clinical Context
Large cooperative-group dataset underpinning adjuvant RT indications and dose recommendations in salivary gland cancer (T3–4, adverse margins, bone/perineural invasion, node-positive necks); still widely cited for dose-response.