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Lower dose IMRT effective for select patients with HPV positive oropharyngeal cancer
CHICAGO — Reduced-dose radiation therapy did not compromise outcomes in patients with HPV-positive oropharyngeal cancer who demonstrated complete clinical response to induction chemotherapy, according to results of a phase 2 study presented at the ASCO Annual Meeting.
“Low-dose radiation after complete response to induction chemotherapy resulted in a 2-year PFS of 80%,” Anthony Cmelak, MD, professor of radiation oncology at Vanderbilt-Ingram Cancer Center, said during a press conference. “Chemoselection strategies are worthy of further study in this patient population and potentially allows for significant reduction in toxicity while maintaining high PFS and OS. This represents a new paradigm in this select group of patients.”
The study included 90 patients (median age, 57 years) with operable stage III or IVA HPV-positive oropharyngeal squamous carcinoma. The majority of patients (86%) were not current smokers, and 46% never smoked.
All patients underwent induction chemotherapy with paclitaxel, cisplatin and cetuximab (Ertibux; Bristol-Myers Squibb, Lilly). After induction chemotherapy, all patients underwent intensity-modulated radiation therapy (IMRT) along with standard cetuximab.
The 62 patients who demonstrated complete clinical response to induction chemotherapy received reduced-dose IMRT (54 Gy). The other 28 patients received standard IMRT (70 Gy).
Median follow-up was 23.3 months.
The study met its primary endpoint of PFS, according to researchers. The rates of 2-year PFS (80% vs. 65%) and 2-year OS (93% vs. 87%) were higher in the lower-dose IMRT arm.
Researchers reported slightly higher 2-year OS (96%) and PFS (92%) among patients with a ≤10 pack-year smoking history and earlier stage disease.
Lower-dose IMRT would not be appropriate for patients with HPV-negative disease or larger tumors, Cmelak said.
“Treatment for head and neck cancer can be quite grueling, so it’s very encouraging to see we can safely dial back treatment in patients with less aggressive disease and an overall good prognosis, particularly for young patients who have many years to deal with long-term side effects,” Cmelak said. “However, we need longer follow-up, as well as confirmatory phase 3 data, before we can recommend applying this strategy in practice.”
For more information:
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Cmelak A. Abstract #LBA6006. Presented at: ASCO Annual Meeting; May 30-June 3, 2014; Chicago.
Disclosure: The researchers report research funding and honoraria from Bristol-Myers Squibb, and consultant/advisory roles with AVEO and Bristol-Myers Squibb. The research was supported by the NIH.
Perspective
Back to TopWe have known for some time that patients with HPV-positive oropharyngeal cancer have a better prognosis than those with non-HPV tumors. This study shows that lowering the dose of radiation may be safe and effective for this group of patients if they respond well to induction chemotherapy. Understanding the biology of cancer allows us to offer more precise therapies for individual patients, and this research offers one more way to provide effective treatment with less toxicity, improving patients’ quality of life.
Perspective
Back to Top
We now have an opportunity to reduce the standard therapy dose at a lower risk to — and with a better response in — this group of patients. This is another way of tailoring and targeting therapy and reducing the long-term toxicities in a group of patients who are likely to do very well with this treatment.