Eighty patients were accrued between September 2013 and June 2016 with all patients completing treatment. Eligible patients included those with HPV-related OPSCC who had no evidence of residual disease following surgery and a minimal smoking history (e.g., less than one pack per day for 10 years or less). The median patient age was 60.5 years (range 25-77 years). All patients had stage III or IV disease. The median follow-up for this report was 24 months (range 12-46 months).

At a median follow-up of two years after de-escalated treatment, the rate of tumor control in the oropharynx and surrounding region was 95 percent. Of the 80 patients in the trial, three experienced a local recurrence and one patient experienced a regional recurrence. Disease-free survival (DFS) following the dose-reduced treatment was 89 percent. By comparison, the RTOG 0234 clinical trial reported a two-year DFS rate of 86.4 percent for patients with HPV-related cancers.


Grade 2 or higher side effects were reported in one percent of patients at one year following treatment and ten percent at two years following treatment. By comparison, studies of adjuvant radiation for OPSCC generally report rates of late grade 2 or higher side effects at more than 50 percent (e.g., 55 percent on RTOG 0234). No patients had grade 3+ toxicity at one year or two years following treatment. Fourteen patients (18 percent) experienced cumulative grade 3+ toxicity within three months of treatment; all instances resolved by six months post-treatment. One additional patient experienced a temporary grade 4 event related to a chemotherapy reaction.

Patients’ ability to swallow improved slightly at one year following radiation therapy compared to pre-treatment (p = 0.03). Swallowing function was measured using the Modified Barium Swallow Impairment Profile (MBSImP). Importantly, no patients needed to have a feeding tube placed during treatment.

Patient’s quality of life largely improved or did not change following treatment, except for dry mouth. Patients reported somewhat worse salivary flow following treatment (p < 0.0001), as measured by the University of Michigan’s Xerostomia QOL scale (XeQOLS). However, none of the other quality of life scales declined significantly—including the Functional Assessment of Cancer Therapy – Head and Neck Version 4 (FACT H&N), the EuroQol EQ-5D and the European Organisation for Research and Treatment of Cancer instrument for head and neck cancer (EORTC-HN). Each measure was assessed prior to radiation therapy and again at one, three, 12 and 24 months following treatment.

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