SAN DIEGO – A survey of radiation oncologists indicated that use of prophylactic cranial irradiation (PCI) in extensive-stage small cell lung cancer (SCLC) has dropped rapidly following a 2017 Japanese trial that found no survival benefit with the approach over MRI surveillance.
Among 49 academic radiation oncologists specializing in thoracic cancers, the proportion offering PCI to patients with extensive-stage SCLC dropped from 78% to 38% following the study (P<0.001), Olsi Gjyshi, MD, PhD, of MD Anderson Cancer Center in Houston, reported in a press briefing ahead of the Multidisciplinary Thoracic Cancers Symposium here.
Gjyshi said a similar decline was seen in a broader follow-up survey, with responses from 431 radiation oncologists in private or government practice as well as from academic centers.
The study in question was a randomized trial by Toshiaki Takahashi, MD, of Shizuoka Cancer Center in Japan, and colleagues, of 224 patients with extensive-stage SCLC who had responded to chemotherapy. They found that while fewer patients receiving PCI developed brain metastases than those receiving close MRI surveillance (48% vs 69%, respectively), this did not translate into a survival advantage.
“They actually saw a trend toward the opposite — decreased overall survival,” Gjyshi explained. “This was not statistically significant, but it did result in the early interruption of the trial.”
Median overall survival was 11.6 months for the PCI group versus 13.7 months for the surveillance group (HR 1.27, 95% CI 0.96-1.68, P=0.094).
In the current study, all 49 academic radiation oncologists who responded to the survey reported being aware of the findings, and two-thirds said the publication had changed how they treat patients with extensive-stage SCLC.
“The practice of PCI in patients with extensive-stage small cell lung cancer is rapidly evolving,” Gjyshi said. “Both MRI surveillance and PCI are acceptable options, with MRI surveillance becoming more predominant.”
Prior to the Japanese study, National Comprehensive Cancer Network (NCCN) guidelines strongly urged PCI for these patients, but this changed in the 2019 NCCN guidelines, which now recommend either PCI or MRI surveillance in this setting.
To confirm their findings, Gjyshi’s group conducted a nationwide survey of American Society for Radiation Oncology (ASTRO) members. Among 431 respondents, a similar shift in practice was seen for the treatment of extensive-stage SCLC. In the academic setting, 74% reported offering PCI before 2017 versus 43% afterward. And in private or government practices, the rate dropped from 69% to 44%, respectively (P<0.001 for both).
“Not surprisingly, physicians are now more likely to defer prophylactic cranial irradiation, and instead now they’re more likely to perform MRI brain surveillance for patients,” said press briefing moderator Charles B. Simone II, MD, of New York Proton Center in New York City. “While older trials have demonstrated survival benefit from the addition of prophylactic cranial irradiation in patients with extensive-stage small-cell lung cancer, clinical practice since then has evolved, including the now more widespread use of MRI brain imaging and also advanced chest imaging for assessing the thoracic response to frontline chemotherapy.”
But in the ASTRO membership survey, about 10% of radiation oncologists were unaware of the study from Takahashi and colleagues; among this group, 82% said they still routinely offer PCI for patients with extensive-stage SCLC.
For limited-stage disease, 23% of the physicians said the study had influenced their practice, and 12% and 25% said they were seeing fewer referrals for PCI in limited- and extensive-stage SCLC, respectively.
“Knowledge of these current clinical practices may help to inform future clinical trials investigating or even incorporating the long-standing practice of routine prophylactic cranial irradiation delivery,” Simone said.
The large majority of respondents in the ASTRO survey said they would be willing to enroll patients in trials testing PCI versus MRI surveillance.
To conduct their study, the researchers sent their anonymous survey in September 2018 to 205 radiation oncologists specializing in thoracic cancers at over 100 academic centers. For nearly half (42%), patients with lung cancer made up the majority of their practice. Two-thirds of respondents came from large centers with at least 10 radiation oncologists on staff.
Gjyshi’s group then sent the 24-question survey to 3,600 ASTRO radiation oncologists across the nation. They found no significant trends in PCI usage by SCLC patient volume, location of practice, or number of years a physician was in practice.
Gjyshi disclosed no relevant relationships with industry. One co-author reported relationships with STCube Pharmaceuticals, Roche/Genentech, Hitachi Chemical, New River Labs, Beyond Spring Pharmaceuticals, and AstraZeneca.