We carried out this study to define the incidence of radiographic retropharyngeal lymph node (RPLN) involvement in oropharyngeal cancer (OPC) and its impact on clinical outcomes, which have not been well established to date.
Our departmental database was queried for patients irradiated for OPC from 2001–2007. Analyzable patients were those with imaging data available for review to determine radiographic RPLN status. Demographic, clinical, and outcomes data were retrieved and analyzed.
The cohort consisted of 981 patients. Median follow up was 69 months. The base of tongue (47%) and tonsil (46%) were the most common primary sites. The majority of patients had T1-2 primaries (64%) and 94% stage 3-4B disease. IMRT was used in 77%, and systemic therapy was delivered to 58%. The incidence of radiographic RPLN involvement was 10% and highest for pharyngeal wall (23%) and lowest for base of tongue tumors (6%). RPLN adenopathy correlated with a number of patient and tumor factors. RPLN involvement was associated with poorer 5-year outcomes on univariate analysis (p <.001 for all): local control (79% vs. 92%), nodal control (80% vs. 93%), recurrence-free (51% vs. 81%), distant metastases-free (66% vs. 89%), and overall survival (52% vs. 82%), and maintained significance for local control (p=.023), recurrence-free (p=.001), distant metastases-free (p=.003), and overall survival (p=.001) on multivariate analysis.
In this cohort of nearly 1000 patients investigating radiographic RPLN adenopathy in OPC, RPLN involvement was observed in 10% of patients and portends a negative influence on disease recurrence, distant relapse, and survival.