Outcomes and prognostic factors for surgery followed by modern radiation therapy in parotid gland carcinomas

Objective: To evaluate the outcomes and prognostic factors in patients with parotid gland cancers treated with adjuvant radiotherapy with or without chemotherapy.Methods: Eighty-five patients with parotid gland cancers were identified between October 2001 and September 2011. The median radiation dose was 66 Gy (range, 9-76 Gy). The outcomes assessment included overall survival, locoregional control, distant metastasis-free survival and disease-free survival.Results: The stage distribution was 20 patients (23.5%) in stage I, 28 (32.9%) stage II, 14 (16.5%) stage III and 23 (27.1%) stage IV. Fifty-five patients (64.7%) had positive margins and 23 patients (27.1%) had close margins (<0.5 cm). Lymph node extracapsular spreading occurred in nine patients. The adjuvant therapy included radiotherapy alone in 47 patients (55.3%) and concurrent chemoradiotherapy in 38 patients (44.7%). With a median follow-up of 4.5 years (range, 0.4-11 years), the 5-year overall survival, locoregional control, distant metastasis-free survival and disease-free survival were 82.0, 88.4, 82.4 and 77.5%, respectively. Based on multivariate analysis, N1/N2 was a significant negative prognostic factor for distant metastasis-free survival, disease-free survival and overall survival. Perineural invasion was a significant negative prognostic factor for locoregional control, distant metastasis-free survival and disease-free survival. Patients 50 years or older had significantly worse distant metastasis-free survival, disease-free survival and overall survival.Conclusions: Surgery and radiotherapy treatment could achieve excellent outcomes in a modern cohort. However, N1/N2, perineural invasion and age ≥50 years, but not positive margins, are significant factors associated with a worse prognosis.