BOSTON-Survival rates for elderly patients with early stage lung cancer have significantly improved since stereotactic body radiation therapy (SBRT) has become more widely used, according to results of a study presented at the 58th Annual Meeting of the American Society for Radiation Oncology.
Researchers based their findings on an analysis of patient data contained in the NCI's SEER program database. They found survival rates for NSCLC patients over the age of 60 rose an estimated 40-60 percent in the past decade, concurrent with increased use of SBRT (Radiat Oncol 2016;96:2 Supplement: S68).
"Since 2004, we've seen a dramatic increase in the adoption of stereotactic body radiation therapy in the community," said lead author Andrew M. Farach, MD, a radiation oncologist at Houston Methodist Hospital, during a press conference.
"With only academic centers providing stereotactic body radiation therapy in 2004 to now, where pretty much all cancer centers have the ability to deliver, this has significantly improved treatment modality with cancer control outcomes."
SBRT & Survival
Farach and his colleagues reviewed records for 62,213 patients who were diagnosed with stage 1 NSCLC between 2004 and 2012, including those with definite records defining local therapy.
Overall survival (OS) and lung cancer-specific survival (CSS) rates were calculated for patients, and they were grouped into 5-year subsets (60-64 years, 65-69, 70-74, 75-79, 80-84, 85-89, and 90 and older). The investigators then analyzed OS and CSS change over time, based on type of therapy as well as patient age.
Over the study period, survival rates for SBRT increased dramatically. From 2004 to 2012, when adoption of SBRT in community practice became widespread, the 23-month OS rate after SBRT alone rose nearly 20 percentage points, from 39 to 58 percent. Rates for surgery alone rose five percentage points, from 79 to 84 percent.
During the same period, CSS increased from 48 to 72 percent of patients who received SBRT alone and from 87 to 91 percent of patients who only received surgery.
The use of surgery to treat stage 1 NSCLC declined with age (p < 0.001). While 81 percent of patients ages 60-64 underwent surgery, only 47 percent of patients ages 80 or older were able to undergo surgery. The use of RT, conversely, rose with increasing age, ranging from 11 percent of patients ages 60-64 to 39 percent of patients ages 90 or above (p < 0.001). The number of patients receiving no treatment also increased from 7 percent to 40 percent for the youngest and oldest elderly patient cohorts in the study.
Despite improvements in OS and CSS, survival rates following RT remained lower than those for elderly patients who received surgery. Researchers explained that this difference may be due, in part, to a selection bias where healthier patients were treated with surgery, and they underscored the need for a controlled clinical trial with matched patients receiving each treatment first-line to compare the efficacy of these therapies. Instances of palliative SBRT or conventional RT also may have skewed results in favor of surgical outcomes.
"The findings indicate that physicians should feel confident recommending SBRT to patients who are too sick to undergo surgery, or who choose not to undergo surgery for other reasons, explained Farach. "With continued adoption of stereotactic body radiation therapy in community cancer centers, it is our hope that more patients will receive curative stereotactic body radiation therapy and the number of patients left untreated, based on age or medical comorbidity, will continue to fall."
A controlled clinical trial of matched patients receiving each treatment as a first-line therapy is now needed in order to compare efficacy surgery and stereotactic body radiation, according to the researchers.
Improved Treatment Access
In recent years, SBRT has become the standard of care for patients with inoperable early stage NSCLC. Compared to the conventional radiation therapy approach of small doses given daily over several weeks, SBRT delivers a highly targeted, escalated dose of radiation in a single session or as many as five of treatments, usually between one and five fractions.
Widespread adoption of SBRT in community-based practices has increased its use as the primary definitive treatment for elderly patients, who often have multiple medical problems that limit surgical options.
"While survival rates remain highest for surgical candidates, this study demonstrates both clear benefits from stereotactic body radiation therapy 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," Farach said.
"It's a rare situation where the more convenient therapy is also the more effective therapy," he noted. "Stereotactic body radiation therapy may now help to improve access to care for elderly patients who may in the past have found it very difficult to come for 6 weeks of daily radiation treatment."
Future Implications
"Over longer follow-up, it is apparent that SBRT has very good rates of local control and survival in these clinical settings, establishing its efficacy," said Puneeth Iyengar, MD, PhD, Assistant Professor of Radiation Oncology, University of Texas Southwestern Medical Center's Simmons Comprehensive Cancer Center, Dallas.
Prior to SBRT, patients without surgical options were treated with conventionally fractionated radiation, which led to poor local control and early mortality. "As expected, with increasing patient age, surgical use became more limited as treatment with radiation or observation became more prevalent," Iyengar said.
"This new analysis falls in line with several recent papers that have highlighted the safety and efficacy of SBRT in the curative treatment of elderly patients with early stage NSCLCs, including septuagenarians and octogenarians," Iyengar continued. "In previous eras, more elderly patients who could not undergo surgery were either treated with conventional radiation or observation with limited benefit. At this time, SBRT can be administered safely and effectively, with improved tumor control and survival and minimal morbidity.
"In the future, we may continue to see higher rates of survival improvement as SBRT continues to be adopted for early stage NSCLC and with combination therapies involving SBRT and less morbid systemic therapies, including potentially immunotherapy or targeted therapies," he concluded.
Kurt Samson is a contributing writer.