Clinical prognostic factors to guide treatment strategy for HPV-positive oropharyngeal cancer from treatment outcomes of induction chemotherapy: A real-world experience.

e18014 Background: The role of induction chemotherapy (IC) in locally advanced oropharyngeal cancer (OPC) remains a topic of debate and suitable candidates for de-escalation treatment in these patients have not been fully identified. This study aimed to identify high-risk groups for HPV-positive OPC by analyzing patients who underwent IC followed by chemoradiotherapy (CRT) to guide optimal treatment strategies. Methods: Between 2004 and 2020, we reviewed patients with OPC diagnosed with stage III-IVA who underwent a treatment regimen comprising a minimum of two cycles of IC followed by CRT.In this study, all patients were re-staged according to the American Joint Committee on Cancer (AJCC) 8 th edition, and we analyzed the overall response rate and survival outcomes associated with clinical factors based on HPV status by utilizing univariate and multivariate analyses. Results: This study analyzed 105 patients with a median age of 60 years (range: 40–76 years). Among 105 patients, 40 (38.1%) were HPV-negative, and 65 (61.9%) were HPV-positive. Through a median follow-up of 60.0 months (range, 5–60 months), no significant differences in progression-free survival (PFS) (p = 0.172) and overall survival (OS) (p = 0.064) were observed based on HPV status, regardless of no differences in relative dose intensity of IC and cumulative dose of radiation and cisplatin in CRT. In all patients, survival outcomes were notably poorer in patients aged ≥ 60 years ( p = 0.006) and those who did not achieve complete response (non-CR) post-CRT ( p < 0.001), irrespective of HPV status. All have received sufficient IC with a median RDI of 80% or more in both age < 60 years and age ≥ 60 years. Unlike HPV-negative OPC, where age and T stage showed no significant correlation, in HPV-positive OPC, age ≥ 60 years ( p = 0.011) and T4 stage ( p = 0.019) emerged as substantial poor prognostic factors for survival outcomes despite IC and CRT. Utilizing these results, we categorized HPV-positive OPC patients into three groups based on the number of clinical risk factors at diagnosis (age, T4 stage), the PFS and OS showed significant stratification across each group as the number of clinical risk factors increased. Conclusions: This study revealed that age and T stage significantly influenced on prognosis in HPV-positive OPC but not in HPV-negative OPC. Considering our result, HPV-positive OPC exhibiting these risk factors requires a careful treatment strategy, and combined treatments, including immunotherapy, may be considered to enhance treatment outcomes for these patients.