SAN ANTONIO — Less intense treatment of low-risk human papillomavirus (HPV)-related oropharyngeal cancer achieved a high rate of pathologic complete response (pCR) and favorable patient-reported outcomes, a preliminary trial showed.
Overall, 37 of 43 (86%) patients achieved pCR with deintensified chemoradiation, including all but one evaluable primary tumor. The pCR rate was virtually identical to historical rates achieved with standard regimens, according to Bhishamjit Chera, MD, of the University of North Carolina (UNC) at Chapel Hill, and colleagues.
Selected patient-reported adverse events peaked during the first 6 to 8 weeks and then declined thereafter. About 40% of patients required feeding tubes for a median duration of 15 weeks, but no patients required permanent feeding tubes, they reported here at the American Society for Radiation Oncology meeting.
The regimen consists of lower doses of radiotherapy and concurrent cisplatin, administered over 6 weeks. With high-dose therapy, the radiation protocol requires an additional week.
“Though we have limited follow-up, the pathological complete response rate with this reduced-intensity chemoradiotherapy regimen is very high in patients with favorable-risk oropharyngeal squamous-cell carcinoma,” Chera said. “The early quality-of-life measurements are encouraging, particularly the data on swallowing. We are optimistic that these results with reduced-intensity treatment will translate into good long-term disease control with less toxicity.”
The study reflects the current trend and momentum in the management of HPV-positive oropharyngeal cancer, said Zain Husain, MD, of Yale Cancer Center in New Haven, Conn.
“This is the second study to show that de-escalation of therapy might work, and so far, the results really look good,” Husain told MedPage Today. “This is a really important issue, and all of our trials are moving in that direction.”
NRG Oncology (formerly RTOG) has already launched a trial using the UNC regimen, “which gives us a lot of confidence that this is a good regimen,” Husain added. Nonetheless, reduced-intensity treatment remains investigational and should not be used in clinical practice. Randomized clinical trials with adequate follow-up will be required to determine the ultimate role of less intense therapy for HPV-positive oropharyngeal cancer, he said.
HPV-positive oropharyngeal cancer accounts for 60% to 70% of new cases of oropharyngeal cancer in the U.S., and the incidence has continued to rise. In general, HPV-positive disease has a more favorable prognosis as compared with HPV-negative oropharyngeal cancer.
At many institutions, standard therapy for newly diagnosed HPV-positive oropharyngeal cancer consists of total-dose radiotherapy of 70 Gy administered over 7 weeks, and concurrent cisplatin 100 mg/m2 for 3 weeks. The regimen achieves a high rate of pCR but causes substantial toxicity. Given the overall favorable prognosis of HPV-positive oropharyngeal cancer, many specialists have begun to ask whether reduced-intensity treatment might be just as effective with less toxicity.
Chera reported findings from a prospective phase II trial of reduced-intensity chemoradiation for low-risk HPV-positive oropharyngeal cancer. Eligible patients had diagnoses of T0-3, N0-2c, M0 disease associated with minimal or negative smoking history. Treatment consisted of a total radiation dose of 60 Gy administered in 2-Gy fractions daily for 6 weeks, plus concurrent weekly cisplatin 30 mg/m2. The regimen represented a 10-Gy reduction in the usual radiation dose and a 40% reduction in the usual chemotherapy dose, Chera said.
The primary outcome was pCR and was based on experience with usual high-dose therapy, which has been associated with a pCR rate of 87%. Patients undergo biopsy of the primary site 6 to 14 weeks after completing chemoradiation, as well as resection of any initially-positive lymph nodes. Secondary endpoints included toxicity, quality of life (QOL), and clinical outcomes of treatment.
The 86% pCR rate compared favorably with the 87% rate demonstrated by historical data. The overall results included pCR in 40 of 41 evaluable primary tumors (two of which were stage T0 at baseline) and pCR in the neck in 33 of 39 patients (four of whom had N0 status at baseline).
After a median follow-up of 21 months, all 43 patients remain alive and without evidence of disease, including 38 patients who have at least 1 year of follow-up.
Investigators evaluated QOL by means of an instrument developed by the European Organization for Research and Treatment of Cancer (EORTC QLQ H&N-35). Focusing on common adverse effects of chemoradiation for head and neck cancer, Chera noted that the severity score for dry mouth, sticky saliva, and swallowing all increased during the first 6 to 8 weeks, particularly dry mouth and sticky saliva.
The score for dry mouth peaked at about 70 on the 100-point scale and the score for sticky saliva rose to a maximum of about 60. Score for dry mouth remained at about 60 at 12 months, whereas the saliva score declined to about 40. The effect on swallowing was less severe, reaching a maximum of about 20 and then declining to less than 10 at 12 months.
Patient-reported symptoms exhibited a similar pattern as the dry mouth score averaged less than 0.5 (0 to 4 scale) at baseline, increasing to almost 2.5 at 6 to 8 weeks, and then declining to less than 2.0 by 1 year. Patient-rated swallowing difficulty was less than 0.5 at baseline, about 1.0 at 6 to 8 weeks, and slightly less than 1.0 at 1 year.
Physician-rated grade 3/4 toxicity and patient-rated severe/very severe toxicity included mucositis (34%/45%), pain (5%/48%), nausea (18%/52%), vomiting (5%/34%), dysphagia (39%/55%), and xerostomia (2%/75%).
Chera and colleagues have already closed enrollment for another phase II trial that will evaluate a reduced-intensity regimen that makes surgery optional, omits chemotherapy for patients with T1-2 N0-1 disease, and includes patients with as much as a 30 pack-year smoking history but who have a 5-year period of abstinence.
A planned “third-generation” phase II trial will evaluate the feasibility of cancer genetics risk-based stratification of patients and examine more specifically the question of whether reduced-intensity treatment is possible for patients with a >10 pack-year smoking history.
*This news story was resourced by the Oral Cancer Foundation, and vetted for appropriateness and accuracy.