March 16, 2010 - In a recent study, highly-focused stereotactic body radiation therapy (SBRT) proved it can eliminate the targeted tumor, while avoiding treatment-related illness, according to early findings of a Radiation Therapy Oncology Group study published in the March 17 cancer-themed issue of the Journal of the American Medical Association.
The study concluded SBRT may ultimately improve survival for patients with inoperable non-small cell lung cancer.
The primary finding was the high rate of primary tumor control (97.6 percent at 3 years). Primary tumor control is an essential requirement for the cure of lung cancer. According to the principal investigator, Robert Timmerman, M.D., of the University of Texas Southwestern Medical Center, Dallas, SBRT as delivered in RTOG 0236 provided more than double the rate of primary tumor control previously reported for conventional radiotherapy. This suggestd that SBRT could provide a significant step forward in the battle against this type of lung cancer.
Currently, patients with inoperable early stage lung cancer are treated with conventional radiation treatment (most commonly given during 20-30 outpatient treatments) or are observed without specific cancer therapy, and have less than ideal outcomes.
"Most ultimately die specifically from progressive lung cancer with observation, and 2-year survival is less than 40 percent with either approach. Our study suggests that stereotactic body radiation therapy is a new option that produces better outcomes and may represent an updated, and ultimately more successful, approach to the treatment of patients with early stage inoperable lung cancer,” said Timmerman.
This is the first North American multicenter, cooperative group study to test SBRT in treating medically inoperable patients with early stage non-small cell lung cancer. Dr. Timmerman and RTOG member investigators enrolled 59 patients to this phase II study that included patients 18 years or older with biopsy-proven peripheral T1-T2N0M0 non-small cell tumors (measuring less than 5 cm. in diameter) and medical conditions that would not allow surgical treatment. Radiation treatment lasted between 1.5 and 2 weeks. The study opened May 2004 and closed October 2006, with data analyzed through August 2009. The final study population included 55 evaluable patients (44 with T1 tumors and 11 patients with T2 tumors), with a median (midpoint) follow-up of 33.4 months.
The primary outcome measured for the study was 2-year actuarial primary tumor control; secondary end points were disease-free survival (i.e., primary tumor, involved lobe, regional, and disseminated recurrence [the reappearance or return of a cancer in multiple areas of the body]), treatment-related toxicity, and overall survival.
Of all the patients in the study, only one experienced a documented tumor recurrence or progression at the primary site. The 3-year primary tumor control rate was 97.6 percent. Three patients had recurrence within the involved lobe; the 3-year primary tumor and involved lobe (local) control rate was 90.6 percent. Combining local and regional failures, the 3-year local-regional control rate was 87.2 percent. Disseminated recurrence as some component of recurrence was reported in 11 patients. The 3-year rate of disseminated failure was 22.1 percent with 8 such failures occurring prior to 24 months.
Disease-free survival and overall survival at 3 years were 48.3 percent and 55.8 percent, respectively. Median disease-free survival and overall survival for all patients were 34.4 months and 48.1 months, respectively. Seven patients (12.7 percent) and two patients (3.6 percent) were reported to experience protocol-specified treatment-related grade 3 and 4 adverse events, respectively. No grade 5 treatment-related adverse events were reported. Higher grades indicate greater severity of adverse event, with grade 5 indicating death.
According to Walter J. Curran, Jr., MD, the RTOG Group Chair, and the Executive Director of the Winship Cancer Institute of Emory University, “RTOG 0236 demonstrated that technologically intensive treatments like SBRT can be performed in the cooperative group setting so long as effective quality control measures are in place to assure patient safety. As the preeminent group conducting multi-institutional clinical trials of novel radiation therapy techniques, RTOG is building on these results to improve patient outcomes and quality of life with trials designed to address the rather high rate of disseminated failure observed after treatment, determine a safe and effective dose for central lung tumors, and refine the dose of SBRT for peripheral tumors.”
RTOG is a National Cancer Institute-funded national clinical trials group and is administered by the American College of Radiology.
Timmerman, R; Paulus, R; Galvin, J; Stereotactic Body Radiation Therapy for Inoperable Early Stage Lung Cancer. JAMA. 2010;303(11):1070-1076.
For more information: www.jama.ama-assn.org/