Stereotactic body radiotherapy (SBRT) effective for inoperable early stage lung cancer
Analysis of data from an institutional patient registry on stereotactic body radiotherapy (SBRT) indicates excellent long-term, local control for medically inoperable, early stage lung cancer patients. Local control was obtained in 70% of tumors in these patients. This research was presented at the 2014 Multidisciplinary Symposium in Thoracic Oncology, held in Chicago, Illinois.
The 300 patients in the study had 340 tumors and were treated from October 1, 2003 through December 31, 2012, at the Cleveland Clinic in Ohio, which was one of the early adopters of SBRT technology for patients with lung cancer in the United States. Patients in the study had a median age of 74 years (range 37-97 years), a median Karnofsky Performance Status (KPS) of 80 (range 40-100), and were not candidates for surgery because of associated medical conditions, of which chronic obstructive pulmonary disease (COPD) was the most common (62%).
Median follow-up was 17.4 months, with 47% patients alive at the time of follow-up. Median tumor diameter was 2.4 cm, and 36% of tumors had either no biopsy or a nondiagnostic biopsy. Fifteen percent of patients received two or more SBRT treatments.
SBRT for lung cancer necessitates accurate and custom mapping of each individual patient's anatomy and a way of accounting for breathing motion to optimally target tumors while sparing as much of the surrounding healthy tissue as possible.
In this study, all patients were uniformly treated using a vacuum-bag immobilization system and abdominal compression to limit breathing effects. Then, CT images were acquired to record tumor motion when at rest, full inhalation, and full exhalation. These three images merged together generated the internal target volume (ITV) of the tumors, essentially representing a virtual map of tumor motion.
The overall rate of any toxicity was 13.0%, with most patients having minimal toxicities (grade 2 or less). No grade 4 or 5 toxicity events were recorded. The most common occurrences were chest wall toxicity (7.7%) and pneumonitis (inflammation of the lung tissue; 4.1%).
At 5 years post-treatment, local control was 79.0% versus 75.4% for patients with central tumors vs. noncentral tumors, respectively. The distant metastases-free and disease failure-free rates were 50% vs 57%, and 37% vs 34%, respectively. Overall survival was 18% vs 20%, respectively. The failure rates of the central versus noncentral tumors utilizing all parameters had no statistically significant differences.
“We have been privileged in demonstrating that lung SBRT can now be considered the standard of care for medically inoperable patients with early stage lung cancer,” said lead study author Gregory M.M. Videtic, MD, a radiation oncologist at the Cleveland Clinic Foundation and associate professor of radiation oncology at the Cleveland Clinic Lerner College of Medicine, Case Western Reserve University. “Since our results indicate no unusual long term side effects, we are hoping to extend the potential uses of this therapy to more fit, operable lung cancer patients whose cancer has not spread outside of the lung and to collaborate with other institutions on conducting such a clinical trial. SBRT could provide a more minimally invasive procedure than surgery, with fewer side effects and improved patient outcomes.”