Clinicians have tapped into the potential of stereotactic body radiation therapy (SBRT) for nearly two decades as a treatment for patients with early stage lung cancer who are not candidates for surgery. But despite ongoing studies and new data, some recently presented at the September ASTRO 2016 annual meeting in Boston, many physicians remain unaware of SBRT as an alternative to surgery, according to radiation oncologists at the Cleveland Clinic Foundation, Cleveland, Ohio.
Gregory M.M. Videtic, MD, section head for thoracic malignancies in the Department of Radiation Oncology, says that other than physicians who specifically care for lung cancer patients, many doctors are not familiar with lung SBRT treatment for four main reasons:
Dr. Videtic presented the findings of a phase II, multi-institutional randomized study conducted to compare incidence of RTOG grade 3 or higher adverse events associated with two different, established SBRT regimens for non-small cell lung cancer (NSCLC). A total of 98 patients participated, randomized to receive either 30 Gy in 1fraction or 60 GY in 3 fractions delivered over at least 8 days. Baseline patient and tumor characteristics were balanced between the two groups of participants. The study was led by Anurag Singh, MD, professor of oncology and director of radiation research in the Department of Radiation Medicine at Roswell Park Cancer Institute in Buffalo, New York, working with collaborators at Cleveland Clinic and the Upstate New York Medical University in Syracuse.
Data from about 84 of the patients were available for analysis at 2-year follow-up. The research team determined that the single-dose regimen, which cut patients’ total radiation in half, was at least as effective as the three-dose schedule. Specifically, overall survival at two years was 70% for the single treatment group, and 64% for the multiple-treatment group. Progression-free survival at one year was 63% and 50% for each group, respectively. Side effects experienced by both groups of patients were also comparable.
“Our goal is always to right-size treatment, and we’re especially excited any time we can show that less treatment can be at least as effective as a more intense regimen, maybe even more so,” said Dr. Singh. “Our findings were surprising, because we previously thought that you would sacrifice some measure of efficacy by reducing radiation exposure to this extent. So we were thrilled that that is not the case.”
“There are a lot of important implications here, in terms of patient convenience and quality of life — especially for those who don’t live close to a cancer center — and the ability to combine radiation therapy with immunotherapy or surgery,” he added.
Survival rates for elderly patients with stage I NSCLC have increased from 40% to 60% over the past 10 years, a trend concurrent with the increasing adoption of SBRT as a treatment, according to a retrospective study of 62,213 patients diagnosed and treated between 2004 and 2012. Andrew M. Farach, a radiation oncologist at Houston Methodist Hospital, also presented these findings in a scientific session at the ASTRO annual meeting. Cancer-specific survival rates increased from 48% to 72% for patients who received SBRT. (The rate increased from 87% to 91% for patients who had surgery.)
Dr. Farach said that the use of surgery declined with the age of the patient, noting that while 81% of patients aged 60-64 underwent surgery, only 47% of patients age 80 or over did. Conversely, the use of SBRT increased with age, with 39% of patients age 90 or older receiving SBRT, compared to 11% of patients ages 60-64.
“While survival rates remain highest for surgical candidates, this study demonstrates both clear benefits from SBRT for nonsurgical NSCLC patients, and that outcomes following radiation therapy have improved at a more accelerated pace over the past decade than those for any other therapeutic approach,” he said. “With increased access to this potentially lifesaving treatment, we can continue to improve outcomes for the growing population of elderly patients fighting early stage cancer.”
Dr. Videtic concurs. “Over the years, the patient with medically inoperable early stage lung cancer has seen a paradigm shift with respect to care,” he wrote in editorial discussing quality of life of early stage lung cancer after surgery or SBRT. “SBRT has been shown to provide excellent disease control as well as impressively low rates of treatment-related toxicity.
“Inasmuch as surgery is the standard against which lung SBRT needs to be compared, the evidence available to date on outcomes and quality of life achievable with lung SBRT makes it compare at least favorably with limited resection or VATS-based surgical approaches,” he said.
SBRT: An underutilized treatment for non-resectable early stage lung cancer patients. Appl Rad Oncol.