Optimized Treatment Modalities for HPV-OPSCC in Japan

Study results published in Cancer demonstrated that patients with T1-T2N0 HPV-related oropharyngeal squamous cell carcinoma (OPSCC) could be treated with radiotherapy alone because of the equivalent outcomes of radiotherapy and concurrent chemoradiotherapy.

In addition, researchers found that patients with stage I to stage II HPV-related OPSCC other than those with T1-T2N0 disease could be treated with concurrent chemoradiotherapy with cisplatin at a dose of 160 mg/m2 or less.

“The results of the current study, based on a nationwide observational study, enabled us to report the optimized treatment modality for HPV-OPSCC,” the authors wrote. “Furthermore, we believe that this study provides basic evidence for future clinical trials.”

The retrospective, nationwide, observational study included patients with HPV-related OPSCC from the Head and Neck Registry of Japan who were treated from 2011 to 2014. Overall, 688 patients who were newly diagnosed with HPV-related OPSCC, treated with curative intent at 35 institutions, and had coherent clinical information and follow-up data available were included in the study.

Of 79 patients with T1-T2N0 disease, both the 3-year recurrence-free survival and overall survival (OS) rates were 100% in the group treated with radiotherapy as well as the group receiving concurrent chemoradiotherapy. Moreover, the 3-year OS rates were 94.4% for patients with T1N0 disease and 92.9% for patients with T2N0 disease among the patients treated with upfront surgery.

“Further study would be needed to validate whether patients with T1-T2N0 HPV-OPSCC could be regarded as [a] favorable cohort similar to patients with HPV-negative HNSCC,” the authors wrote.

In those with stage I to stage II HPV-related OPSCC, the 5-year recurrence-free survival and OS rates were 91.4% and 92%, respectively, in the patients treated with concurrent chemoradiotherapy with relatively high-dose cisplatin (≥160 mg/m2; 114 patients) and 74.3% and 69.5%, respectively, in the patients treated with low-dose cisplatin (<160 mg/m2; 17 patients).

“We must note that our suggestion to reduce the dose of cisplatin was supported by the accumulating total dose in the retrospective observational study but not a total dose in the intention-to-treat analysis,” the authors wrote. “Thus, well-designed prospective clinical trials are needed to validate our proposal.”

Importantly, the researchers suggested that the number of patients included in analysis was relatively small for evaluating the impact of adjuvant therapies such as postoperative radiotherapy and postoperative chemoradiotherapy. Even further, although all data used for the study were submitted by board-certified head and neck surgeons, this was a retrospective observational study that could determine correlations but could not determine the best treatment modality.

However, to address these issues, a nationwide, prospective, observational study based on the national Head and Neck Cancer Registry of Japan is currently being conducted. Approximately 2000 patients with HPV-OPSCC have been newly enrolled into the trial each year, and the researchers believe this will provide more reliable real-world evidence to accompany these findings.

“Although these results did not derive from the prospective clinical trials, and we were unable to obtain data regarding toxicity and morbidity, we believe that these simple and convincing results based on real-world data could be a milestone for future clinical practice and would provide preliminary evidence for future clinical trials,” the authors wrote.

Reference:

Saito Y, Hayashi R, Iida Y, et al. Optimization of Therapeutic Strategy for p16-Positive Oropharyngeal Squamous Cell Carcinoma: Multi-Institutional Observational Study Based on the National Head and Neck Cancer Registry of Japan. Cancer. doi: 10.1002/cncr.33062.