Oropharyngeal squamous cell carcinoma (OPSCC) is divided into two entities: human papillomavirus-related (HPV-related) and HPV-unrelated. Although it is established that patients with HPV-related locally advanced OPSCC (LA-OPSCC) survive significantly better than those with HPV-unrelated LA-OPSCC when treated with chemoradiotherapy (CRT), CRT remains the standard treatment for HPV-related LA-OPSCC. Given the young generation being more prone to be affected by HPV-related OPSCC, patients suffer from severe late toxicity associated with CRT for a long time. The hypothesis has emerged that patients with HPV-related LA-OPCC could be well managed by de-intensified treatment, resulting in long-term less morbidity without compromising survival. A series of clinical trials are in progress to certify this hypothesis.
We did a single-arm, phase 2 trial, enrolling patients with newly diagnosed, biopsy-proven, stage III or IV (excluding T4 and/or N3) OPSCC, positive for both p16 and HPV DNA. Patients received intensity-modulated radiotherapy alone for 70 Gy in 35 fractions. The primary endpoint was response at 11th week after treatment, assessed on RECIST and PERCIST.
Between August 2013 and November 2016, 39 patients were enrolled with a median age of 64 years (range, 49-83). The majority of patients (24, 62%) had ≥10 pack-years smoking history. 35 (90%) patients showed complete response on RECISIT and/or complete metabolic response on PERCIST. One patient had regional recurrence, and two had distant metastasis. The 2-year overall survival rate and progression-free survival rate was 96% and 91% (95% CI, 76-99 and 75-97), respectively. During treatment 10 patients had grade 3 adverse events, but no grade 4 events were reported. 7 patients had gastrostomy tube placed during treatment, but no patient was dependent on gastrostomy tube at 4 weeks after treatment.
Radiotherapy alone was associated with high disease control and an improved toxicity profile. Radiotherapy alone has the potential to replace CRT as the standard treatment for HPV-related LA-OPSCC.
Clinical trial identification
UMIN000008953; Release date: 09/20/2012.
Legal entity responsible for the study
Has not received any funding.
All authors have declared no conflicts of interest.