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

Abstract

To evaluate the outcomes and prognostic factors in patients with parotid gland cancers treated with adjuvant radiotherapy with or without chemotherapy. 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 survivaland disease-free survival. 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 chemoradiotherapyin 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. 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.