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ASTRO presentations highlight advances in glioma, prostate cancer, NSCLC
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More than 11,000 clinicians attended the American Society for Radiation Oncology Annual Meeting in September 2014 in San Francisco.
Each year, the ASTRO meeting facilitates scientific reports that refine our understanding of the critical curative and palliative role played by ionizing radiation treatments and by radiation oncologists in the management of cancer patients.
A notable trend at ASTRO meetings over the past 5 years has been the increase in highlighted reports from prospective multi-institutional clinical trials. Although clinical trials have played a central role in defining the best care of patients with cancer for decades, such trials have played a less significant role in many circumstances in which cancer care has involved novel radiation techniques. This may, in fact, be due to the less demanding FDA guidelines for approving new uses of devices as opposed to the guidelines for approving new pharmaceutical agents.
Walter J. Curran
NRG Oncology, a new network group as of March 2014, was formed through a merger of the National Surgical Adjuvant Breast and Bowel Project, the Radiation Therapy Oncology Group (RTOG) and the Gynecologic Oncology Group. Largely through the work already conducted by its legacy group, RTOG, NRG Oncology had 24 presentations at the ASTRO meeting.
The 2014 ASTRO meeting featured several particularly important NRG Oncology reports.
PCV extends survival in glioma
Minesh Mehta, MD, of the University of Maryland presented mature results of RTOG 9802, a randomized phase 3 trial that enrolled 251 adults with higher-risk low-grade glioma. Researchers compared 54 Gy conformal radiation with or without six cycles of PCV chemotherapy, which consists of procarbazine, lomustine and vincristine.
Adults with a diffuse WHO grade 2 glioma confirmed on central pathology review who were either aged older than 40 years or had undergone a subtotal resection were eligible for enrollment.
Mehta reported that the addition of PCV chemotherapy resulted in a significant improvement in long-term PFS (HR=0.5) and OS (HR=0.59), with median survival times of 13.3 years vs. 7.8 years. The result was sufficiently significant as to require closure of an ongoing phase 3 trial being coordinated by ECOG-ACRIN because of the inclusion of a control arm with radiation alone.
Radiotherapy dosing for prostate cancer
Jeff Michalski, MD, of Washington University presented the initial results of the phase 3 RTOG 0126 trial, which enrolled 1,532 men with intermediate-stage localized prostate cancer.
Results of this trial demonstrated that higher-dose (79.2 Gy) radiotherapy vs. standard-dose (70.2 Gy) radiotherapy resulted in fewer men experiencing PSA failures, prostate cancer progression, metastases or initial treatment failure.
Patients in the high-dose radiotherapy arm did not live longer and experienced significantly more grade ≥2 gastrointestinal and genitourinary side effects than patients who received the standard dose. Patients in both study arms were treated using either 3-D conformal radiotherapy or intensity-modulated radiotherapy.
Stereotactic radiation effective in NSCLC
Robert Timmerman, MD, of UT Southwestern presented 5-year follow-up of the RTOG 0236 study, a phase 2 trial that evaluated stereotactic body radiation therapy (SBRT) as primary therapy in 59 medically inoperable patients with early-stage non–small cell lung cancer.
The trial’s 2-year results, published in JAMA in 2010, showed a remarkable local (in-field) tumor recurrence rate of 2% and a 3-year locoregional recurrence rate of 13%. The 5-year results presented at ASTRO — which showed a 7% local recurrence rate and 20% locoregional recurrence rate — are still considered very promising, particularly in view of the lack of grade 5 toxicity and no newly reported grade 4 toxicities.
RTOG, which now carries out research as NRG Oncology, was the first North American cooperative group to evaluate SBRT in a clinical trial.
Manuka honey did not reduce esophagitis
Lawrence Berk, MD, of Moffitt Cancer Center provided the first report of a phase 3 trial designed to reduce incidence of grade 3 esophagitis associated with concurrent chemoradiation for patients with stage III non–small cell lung cancer.
The trial included 163 patients who were randomly assigned to either Manuka honey, a Manuka honey lozenge or placebo. Researchers observed no significant reduction in any esophagitis or mucositis endpoints with either investigational agent.
Conclusion
The NCTN’s five groups will conduct prospective clinical and translational research trials and continue to report important observations at meetings such as the ASTRO Annual Meeting.
Although annual patient enrollment in the legacy cooperative group system ranged from 22,000 to 25,000 over the past 5 years, it is projected that the NCTN system will cap enrollment at less than 18,000 patients per year. There is growing concern that this enrollment cap may delay the testing of many new scientific observations in the appropriate clinical setting. Physician leaders of the network groups will need to be careful stewards of the resources of the NCTN to enable the network to make the greatest level of progress against cancer.
References:
The following were presented at the ASTRO Annual Meeting; Sept. 14-17, 2014; San Francisco:Berk LB. Abstract #CT-07.
Mehta M. Abstract #74.
Michalski J. Abstract #LBA1.
Timmerman R. Abstract #56.