Exploration for an Algorithm for Deintensification to Exclude the Retropharyngeal Site From Advanced Oropharyngeal Squamous Cell Carcinoma Treatment

Abstract

Importance Understanding the drainage patterns to the retropharyngeal nodes is an important consideration in oropharyngeal squamous cell carcinoma (OPSCC) because treatment of these nodes is related to increased morbidity. Prediction of these drainage patterns could not only help minimize treatment morbidity, but could also prevent failures in at-risk patients, as de-escalation trials are underway for this disease. Objective To evaluate the prevalence of pathologic retropharyngeal adenopathy (RPA) in OPSCC relative to involvement of the oropharyngeal subsite, number of neck nodes, T classification and N classification. Design Retrospective review from 2003–2010 Setting Academic Referral Center Participants 205 previously untreated, advanced stage (III, IV), pathologically confirmed patients with OPSCC Exposure: Concurrent chemoradiation Main Outcome Measures Radiologic evidence of pathologic RPA was tabulated and related to involvement of the oropharyngeal subsite, number of neck nodes, T classification and N classification. Results Pathologic RPA was identified in 18% of patients. There were pathologic retropharyngeal lymph nodes in 12/89 (13%) base of tongue cancers, 24/109 (22%) tonsil cancers, and 1/7 (14%) other oropharyngeal subsite cancers. Increasing prevalence of RPA was positively correlated with closer proximity to the posterior tonsillar pillar. A multivariate predictive regression model using the oropharyngeal subsite, involvement of the posterior tonsillar pillar, number of metastatic nodes, T classification, and N classification, showed that the number of metastatic nodes was statistically significant with an odds ratio of 1.436 (p=0.0001, 95% confidence interval: 1.203 – 1.714). Conclusions and Relevance The prevalence of pathologic RPA in this cohort was 18% and patients with multiple nodes had the highest risk for pathologic RPA, followed by involvement of the posterior tonsillar pillar. However, this data suggests that there is no clear algorithm that can be used for de-intensification to exclude the retropharyngeal site from the treatment volume using extent of disease gathered from pretreatment imaging for patients with advanced stage OPSCC.

Radiographic retropharyngeal lymph node involvement in HPV‐associated oropharyngeal carcinoma: Patterns of involvement and impact on patient outcomes

“…Tang et al 5 studied a cohort of 165 patients with OPC, 134 of whom had HPV-associated disease, and observed a 12% incidence of RPLN involvement, similar to the 9% incidence observed in the current study cohort and the 10% incidence observed in our 2013 study, although lower than the incidence of 16% to 21% reported by others. 3,[14][15][16] The discrepancy in the RPLN incidences reported in these study populations compared with that in the current study may be related to differences in the percentage of patients with locally advanced OPC in each study cohort. For example, the percentage of patients with T3-T4 disease in the referenced studies ranged from 46% to 64%, which is higher than the rate of 42% observed in the study by Tang et al 5 and the rate of 28% (224 of 796 patients) observed in the current study.…”

“…However, within the context of other variables, the potential relationship between RPLN and outcomes may be difficult to demonstrate. Tang et al studied a cohort of 165 patients with OPC, 134 of whom had HPV‐associated disease, and observed a 12% incidence of RPLN involvement, similar to the 9% incidence observed in the current study cohort and the 10% incidence observed in our 2013 study, although lower than the incidence of 16% to 21% reported by others . The discrepancy in the RPLN incidences reported in these study populations compared with that in the current study may be related to differences in the percentage of patients with locally advanced OPC in each study cohort.…”

Retropharyngeal Lymph Node Involvement in Oropharyngeal Carcinoma: Impact upon Risk of Distant Metastases and Survival Outcomes

“…A limited number of prior studies have reported RPLN involvement in oropharyngeal carcinoma, with a variable incidence (Table 4) [12][13][14][20][21][22][23]34]. In our series of 402 patients, the rate of radiological RPLN involvement was 10%.…”

“…The imaging used in prior reported series to identify RPLN (Table 4) had varied widely and would be expected to impact upon the rates of RPLN identification. In several prior series examining the incidence of RPLN in oropharyngeal carcinoma, very limited numbers of patients had PET-CT staging [12,13,20,21]. In contrast, in our series, all patients had a staging PET-CT scan in addition to MRI and/or CT.…”

“…Surgical series are small and restricted to highly selected operable patients [18,19], hence limiting their applicability to the wider group of oropharyngeal carcinoma. Imaging studies have reported a very variable incidence of RPLN involvement, with larger series reporting RPLN involvement in 9-21% of oropharyngeal carcinomas [12][13][14][20][21][22][23].…”