Prognostic risk factors and clinical implications of adjuvant radiotherapy in T1/2 major salivary gland cancer

BACKGROUND: This study aimed to investigate the prognostic risk factors for T1/2 major salivary gland cancer. Additionally, we sought to determine the impact of adjuvant radiotherapy, especially in low-grade cancer cases with clinicopathological adverse features. METHODS: A retrospective review of medical records for 93 patients who underwent surgery for T1/2 major salivary gland cancers between January 2000 and December 2024 was conducted. We evaluated clinicopathological adverse features as prognostic factors and compared 5-year disease-free survival (DFS) to determine the influence of adjuvant radiotherapy on prognosis in low-grade cancer cases exhibiting any histological adverse features. RESULTS: Lymphatic invasion was linked to reduced 5-year overall survival in patients with T1/2 major salivary gland cancers (hazard ratio [HR] = 8.563, 95% confidence interval [CI] = 1.202-60.996, P = .032). Regarding 5-year DFS, histological grade and positive nodal metastasis were pinpointed as detrimental prognostic factors (HR = 3.330, 95% CI = 1.023-10.842, P = .046; HR = 9.891, 95% CI = 1.520-64.355, P = .046, respectively). For low-grade cancers presenting with any clinicopathological adverse features, no significant difference was observed in 5-year DFS following adjuvant radiotherapy (86.8% vs. 93.8%, P = .781). CONCLUSIONS: Lymphatic invasion, high histological grade, and positive nodal metastasis were determined as poor prognostic factors in T1/2 major salivary gland cancer. However, adjuvant radiotherapy did not significantly influence the prognosis in low-grade cancer cases with adverse features.