Irradiation for Regionally Only Recurrent, Never-Irradiated Oral Cavity Cancers

Abstract

The outcomes of patients (pts) after salvage radiation therapy (RT) for neck only recurrences of oral cavity cancers (OCC) are not well characterized. Therefore, we seek to report the treatment results and prognostic factors of pts who received RT as part of their salvage treatment for neck only recurrent disease (rT0 rN1-3) of initially node negative (T1-2 N0) OCC without upfront adjuvant RT. The records of consecutive pts who received salvage RT as part of their treatment for neck only recurrent OCC (rOCC) at our institution from 1989-2008 were reviewed. The Kaplan-Meier method was for overall survival (OS), disease specific survival (DSS), freedom from neck/regional failure (FFRF) and freedom from distant metastasis (FFDM). The Cox proportional hazards regression model was used to examine prognostic factors in univariate (UVA) and multivariate analysis (MVA). Time to event was calculated from start of RT. Out of 123 pts with rOCC treated with salvage RT, 44 pts were identified with neck only rOCC and compromised the study cohort. The median time to neck only recurrence from primary diagnosis was 15 mo. (range: 2 to 211 mos). From start of salvage RT, median follow-up for living pts was 125 mo. (range: 8 to 310 mo) and 24 mo. for all pts (4 to 310 mo). Thirty-nine pts (89%) had salvage neck dissection followed by RT, while the remaining 5 pts received definitive RT. Three pts who underwent salvage neck dissection had grossly invasive recurrent neck disease (e.g. large neck mass invading surrounding soft tissue/skeletal muscle, salivary gland, jugular vein, etc.) resulting in positive soft tissue margins on the nodal specimen. Fifteen pts (34%) received chemotherapy as part of their salvage therapy including 3 pts treated with definitive RT. Recurrent N stage was rN1, rN2, and rN3 in 17 (39%), 25 (57%), 2 (4%) pts, respectively. The 5-year OS, DSS, FFRF and FFDM were 32%, 52%, 80%, and 73%, respectively. On MVA of the entire cohort, disease resulting in a positive soft tissue margin after salvage neck dissection was independently associated with worse OS (HR 6.17, P = 0.009) as was lack of salvage surgery (HR: 3.45, P = 0.022). Disease resulting in positive margins was also independently associated with worse DSS (HR: 6.52, P = 0.005) while greater rN-stage (rN2/N3 vs. rN1) was independently associated with worse FFRF (HR: 8.2, P = 0.045). On MVA of the surgical pts subset, only negative surgical margin was independently associated with improved OS (HR: 4.97, P = 0.02) and DSS (HR: 4.92, P = 0.021). Neck only rOCC is a difficult to treat disease with poor outcomes. Pts who are able to undergo salvage neck dissection with disease amenable to achieving negative surgical margins attain the best clinical outcomes. We advocate for appropriate risk stratified treatment of initial disease to improve outcomes.