According to research lead by Gregory M.M. Videtic and presented at the 2014 Chicago Multidisciplinary Symposium in Thoracic Oncology, medically inoperable early stage lung cancer patients treated with stereotactic body radiotherapy (SBRT) have shown excellent local control, demonstrating that SBRT can be considered a standard and indicated treatment for patients with this type of tumor.
Researchers analyzed data from an institutional patient registry and included information about 300 patients treated with SBRT between 2003 and 2012. A total of 340 tumors in 300 patients were treated at the Cleveland Clinic, an early adopter of the SBRT technology in the United States. These patients were not candidates for surgery due to their medical conditions: chronic obstructive pulmonary disease (COPD) was the most common (62%) condition that kept them out from being eligible for the procedure.
Patients had a 74-year median age and a median Karnofsky Performance Status (KPS) of 80. They were followed for an average of 17.4 months and 46.7 percent of patients were alive by that time. The median tumor diameter was 2.4 cm and 36.3 percent of patients had neither biopsy nor non-diagnostic biopsy; 15 percent of patients received 2 or more SBRT treatments.
Each individual subject needs to have their anatomy accurately mapped and breathing motion has to be studied to allow SBRT to be performed with minimal damage to healthy tissues. Patients were treated using a vacuum-bag to immobilize and compress the abdominal region so breathing effects were limited and minimized. A combination of 3 CT images was used to calculate the internal target volume (ITV) of tumors and optimize radiation and targeting: one at rest, one in full inhalation and another in full exhalation.
The overall rate of toxicity was 13 percent and the majority of patients had minimal toxicities (corresponding to grade 2 or less); there were no records of grades 4 or 5. Further, as detailed in the American Society for Radiation Oncology (ASTRO) press release: “The most common occurrences were chest wall toxicity, 7.7 percent, and pneumonitis (inflammation of the lung tissue), 4.1 percent. The toxicity rate for the 115 lesions classified as “central” tumors, according to the RTOG 0813 definition of “within or touching the zone of the proximal bronchial tree or adjacent to mediastinal or pericardial pleura,” vs. non-central tumors (225 lesions) was 15.5 percent (18 lesions) vs. 11.7 percent (27 lesions).”
In patients with central tumors vs non-central tumors, five years after the treatment, local control was 79% vs 75.4 %, the rate of distant metastases-free was 49.5% vs 56.7% , failure-free rates 37.3% vs 34.3 and overall survival rate 18.3% vs 20.3.
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“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,” Gregory M.M. Videtic, MD, 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 stated in the ASTRO press release. “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.”
