Temporal Incidence and Patterns of Distant Failure for Human Papillomavirus (HPV) Related Oropharyngeal Cancer

Abstract

HPV related oropharyngeal cancer (HPV-OPC) enjoys improved treatment outcomes relative to non-HPV related disease but suffers from similar rates of distant metastases (DM) following treatment. Emerging data supports radical intent therapy for oligometastatic relapsed HPV-OPC, suggesting early diagnosis of DM may be beneficial to outcome. We assess temporal patterns in distance relapse to investigate rationalization of post treatment imaging. A retrospective single center cohort study was carried out of consecutive HPV-OPC treated with radical intent (chemo)radiotherapy ((CT)RT) between 2011 and 2020. Electronic records were reviewed to identify location and timing of development of DM. Oligometastatic (OM) state was defined as </ = 5 metastasis in one system. A total of 793 HPV-OPC patients were identified with median follow-up 3.15 years (range 0.2-8.9). The median time to recurrence was 15.1 months (range: 2.6-63 months). 87% of DM occurred in the first two years after treatment. Pattern of failure by stage are shown in table 1. Indications for scans performed identifying DM alone were symptoms (66%), follow-up imaging based on previous radiological findings (15%), disease response assessment imaging (15%), and incidental findings (4%). Sites of distant metastasis were lung (64%), thoracic nodes (36.5%), bone (27%), visceral (23%), brain (4%) and skin (2%). The sites of visceral metastasis involvement included liver (92%), Adrenal (18%), kidney (18%), and spleen (9%). Treatment offered to patients with OM alone was best supportive care (46%), palliative chemotherapy (15.4%), palliative RT (23%), immunotherapy (8%), and one patient lost to follow up (8%). SBRT was not available during time period. Median survival following diagnosis was 17.5 months (range 4.4-85.4 months). Despite no routine imaging beyond initial treatment response assessment, we identify a small minority of HPV OPC patients with OM recurrence that is associated with better outcome and occasional long-term cure from aggressive therapy. The majority (69%) of DM occur in the thorax/upper abdomen of patients in the first two years post treatment. This finding supports the potential utility of regular imaging of thorax/upper abdomen during early follow.