According to researchers, for certain patients with oropharyngeal cancer produced by the human papilloma virus (HPV), an aggressive reduction of radiation therapy after surgery may provide excellent cancer control while simultaneously reducing post-treatment side effects, improving quality of life and lowering treatment costs. This was presented in American Society for Radiation Oncology (ASTRO).
Patients in the phase II clinical trial received half the standard radiation dose but achieved equally high cure rates at two years following treatment. While cure rates are excellent following therapy, treating the sensitive throat and neck regions often causes serious and potentially life-altering side effects. MC1273 was a single-arm phase II trial for HPV-related OPSCC testing clinical outcomes and quality of life with a de-escalated course of radiation therapy.
By following surgery to remove the disease. Patients received two weeks of twice-daily radiation therapy to the oropharynx for a total dose of 30-36 Gray (Gy), a 50 percent reduction of the standard radiation dose of 60-66 Gy. Patients also received two courses of chemotherapy (docetaxel 15 mg/m2), delivered on days one and eight.
The 43 patients with extracapsular extension (ECE), a marker of particularly aggressive disease, received an additional, simultaneous radiation boost to the areas with ECE, for a total dose (including primary treatment) of 36 Gy. 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. 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% on RTOG 0234). 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). They require confirmation in a randomized trial, and this treatment approach should be considered investigational until confirmed in a phase III study, such as the ongoing multi-institutional DART-HPV trial that is currently open for patient accrual.