Analysis of RTOG 0236: Stereotactic Body Radiation Therapy for
Medically Inoperable Early-stage Lung Cancer Patients
Stereotactic body radiation therapy
(SBRT) stopped the growth of cancer at its original site in the lung for three years among nearly 98 percent of patients with early non-small cell lung cancer (NSCLC) who are unable to have the cancer surgically removed, according to an updated three-year study presented November 2, 2009, at the 51st Annual Meeting of the American Society for Radiation Oncology (ASTRO).
The study also shows that more than half (56 percent) of these patients lived for three years after diagnosis, while 48 percent survived for three years after cancer treatment with no sign of the disease returning. Researchers also found that despite the high potency of treatment, less than 20 percent of these extremely frail patients experienced a serious decline in their health status. This finding was better than researchers expected and is similar to the risks for healthier patients to undergo radical surgery.
"The results of the RTOG 0236 study confirms that SBRT should now be considered a standard treatment in early-stage lung cancer patients with co-existing serious medical problems, such as emphysema, heart disease and stroke," Robert D. Timmerman, M.D., lead author of the Radiation TherapyOncology Group (RTOG) study and a radiation oncologist at the University of Texas Southwestern Medical Center in Dallas said. "It also begs the question of whether SBRT should be considered in healthier patients with lung cancer who are treated with surgery."
Stereotactic body radiation therapy is a specialized type of external beam radiation therapy that pinpoints high doses of radiation directly on the cancer in a shorter amount of time than traditional treatments. Cancer centers often call the treatments by the brand names of the manufacturers, including Axesse, CyberKnife, Gamma Knife, Novalis, Primatom, Synergy, X-Knife, TomoTherapy and Trilogy. Treatment in the study was delivered in 1˝ to 2 weeks, instead of a typical period of 6 to 8 weeks. For the past century, the standard treatment for early-stage NSCLC has been radical surgery that has involved removing a lobe or even the entire lung on the affected side. This surgery can be difficult for many patients as other medical conditions can hinder their recovery. The phase II trial took place from May 2004 to October 2006 and involved 55 patients at eight RTOG institutions in the U.S. and Canada. They received SBRT with a dose of 54 Gy in three fractions. The medium follow-up after treatment was 34 months.
Stereotactic Body Radiation Therapy for Inoperable Early Stage Lung Cancer
Context Patients with early stage but medically inoperable lung cancer have a poor rate of primary tumor control (30%-40%) and a high rate of mortality (3-year survival, 20%-35%) with current management.
Objective To evaluate the toxicity and efficacy of stereotactic body radiation therapy in a high-risk population of patients with early stage but medically inoperable lung cancer.
Design, Setting, and Patients Phase 2 North American multicenter study of patients aged 18 years or older with biopsy-proven peripheral T1-T2N0M0 non–small cell tumors (measuring <5 cm in diameter) and medical conditions precluding surgical treatment. The prescription dose was 18 Gy per fraction x 3 fractions (54 Gy total) with entire treatment lasting between 1 and 2 weeks. The study opened May 26, 2004, and closed October 13, 2006; data were analyzed through August 31, 2009.
Main Outcome Measures The primary end point was 2-year actuarial primary tumor control; secondary end points were disease-free survival (ie, primary tumor, involved lobe, regional, and disseminated recurrence), treatment-related toxicity, and overall survival.
Results A total of 59 patients accrued, of which 55 were evaluable (44 patients with T1 tumors and 11 patients with T2 tumors) with a median follow-up of 34.4 months (range, 4.8-49.9 months). Only 1 patient had a primary tumor failure; the estimated 3-year primary tumor control rate was 97.6%. Three patients had recurrence within the involved lobe; the 3-year primary tumor and involved lobe (local) control rate was 90.6% (95% CI, 76.0%-96.5%). Two patients experienced regional failure; the local-regional control rate was 87.2% (95% CI, 71.0%-94.7%). Eleven patients experienced disseminated recurrence; the 3-year rate of disseminated failure was 22.1% (95% CI, 12.3%-37.8%). The rates for disease-free survival and overall survival at 3 years were 48.3% and 55.8%, respectively. The median overall survival was 48.1 months. Protocol-specified treatment-related grade 3 adverse events were reported in 7 patients (12.7%); grade 4 adverse events were reported in 2 patients (3.6%). No grade 5 adverse events were reported.
Conclusion Patients with inoperable non–small cell lung cancer who received stereotactic body radiation therapy had a survival rate of 55.8% at 3 years, high rates of local tumor control, and moderate treatment-related morbidity.