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

Abstract

The influence of retropharyngeal lymph node (RPLN) involvement on prognosis in oropharyngeal carcinoma remains poorly defined. The aim of this study was to assess the impact of RPLN involvement upon outcomes. A single-centre retrospective analysis of 402 patients with oropharyngeal carcinoma treated nonsurgically between 2010 and 2017 was performed. All had a baseline 2-[fluorine-18]-fluoro-2-deoxy-d-glucose (FDG) PET-CT and contrast-enhanced MRI and/or CT. RPLN status was determined by radiology review of cases with reported abnormal RPLN. Multivariate backwards logistic regression was used to examine impact on outcomes of factors. Abnormal RPLNs were identified in 40/402 (10%) of patients. Median follow up was 42.9 months. RPLN involvement was associated with inferior 3 year outcomes for overall survival (OS) (67.1% vs. 79.1%, p = 0.006) and distant metastases-free survival (DMFS) (73.9% versus 88.0%, p = 0.011), with no significant difference in local control (81.6% vs. 87.7%, p = 0.154) or regional control (80.7% vs. 85.4%, p = 0.252). On multivariate analysis abnormal RPLN, no concurrent chemotherapy and ongoing smoking were associated with inferior DMFS and OS, while advanced T stage was also associated with inferior OS. In summary, RPLN involvement, present in 10% of patients, was an independent prognostic factor for the development of distant disease failure translating into inferior OS. These findings need confirmation in future studies.

Detailed patient-individual reporting of lymph node involvement in oropharyngeal squamous cell carcinoma with an online interface

“…Lymph node involvement observed in this study is consistent with previous publications regarding prevalence [8], [12], [13], dependence on upstream levels [17], contralateral spread [11], [18]- [21], and HPV-dependence [14]. This is discussed in more detail in the supplementary materials, appendix A.…”

“…However, the lymphatic drainage of the tonsil is mainly unilateral, therefore an ipsilateral irradiation is recommended for lateralized low T-category (T1/T2) tumors (at least up to lymph node stage N2a). Volume-reduced elective nodal irradiation has been or is being investigated in several trials [10], [11] While the general patterns of lymph drainage in the neck is understood and prevalence of LNL involvement has been reported in the literature [8], [12], [13], [14], the details of progression patterns in oropharyngeal squamous cell carcinomas (OPSCC) are poorly quantified. How much does the risk of level IV involvement increase depending on whether levels II and III harbors macroscopic metastases?…”

Detailed patient-individual reporting of lymph node involvement in oropharyngeal squamous cell carcinoma with an online interface

“…Lymph node involvement observed in this study is consistent with previous publications regarding prevalence [8], [12], [13], dependence on upstream levels [16], contralateral spread [11], [17]- [20], and HPV-dependence [14]. This is discussed in more detail in Appendix B: Comparison to other works and clinical relevance.…”

“…Prevalence of LNL involvement: Overall patterns and prevalence of LNL involvement in our study (Table 1) is consistent with previous studies [8], [12], [13]. Our study contained a relatively low number of N0 patients (16%) compared to previous reports, which may be explained by differences in patient selection and diagnostic modalities used.…”

“…However, the lymphatic drainage of the tonsil is mainly unilateral, therefore an ipsilateral irradiation is recommended for lateralized low T-category (T1/T2) tumors (at least up to lymph node stage N2a). Volume-reduced elective nodal irradiation has been or is being investigated in several trials [10], [11] While the general patterns of lymph drainage in the neck is understood and prevalence of LNL involvement has been reported in the literature [8], [12], [13], [14], the details of progression patterns in oropharyngeal HNSCC are poorly quantified. How much does the risk of level IV involvement increase depending on whether levels II and III harbors macroscopic metastases?…”