ASTRO: Good Primary Tumor Control, Positive 5-Year Survival Rates for Lung Cancer Patients Who Receive Stereotactic Body Radiation Therapy
Patients with inoperable, early-stage lung cancer who receive stereotactic body radiation therapy have a 5-year survival rate of 40%, according to long-term results presented at the American Society for Radiation Oncology’s (ASTRO) 56th Annual Meeting (Abstract 56). Such a positive survival rate is encouraging considering that historically conventional radiation therapy resulted in poor tumor control for patients with inoperable lung cancer. This study is an update of RTOG 0236, originally published in 2010.
RTOG 0236
RTOG 0236 was a phase II North American multicenter trial from May 2004 until October 2006 of patients age 18 and older with biopsy-proven peripheral T1–T2 N0M0 non–small cell lung cancer and medical conditions precluding surgery. Patients received stereotactic body radiation therapy, which delivers high doses of radiation to the tumor in a decreased amount of treatment time while minimizing exposure to surrounding healthy organs. Initial study results suggested that stereotactic body radiation therapy appeared to improve tumor control.
A total of 59 patients were accrued for the study, and 55 were evaluable (44 patients with T1 tumors and 11 patients with T2 tumors). Patients each received three fractions of 18 Gy of stereotactic body radiation therapy, and treatment lasted between 1.5 to 2 weeks.
Long-Term Follow-up
Researchers evaluated local control, as well as disease-free survival, overall survival and toxicity. Median follow-up was 4 years (7.2 years for surviving patients). At 5 years, the rates for disease-free and overall survival were 26% and 40%, respectively, with a median overall survival of 4 years.
Four patients had recurrences at the primary tumor site, resulting in an estimated 5-year primary tumor failure rate of 7% (range, 1.8–4.8 years after stereotactic body radiation therapy). Nine additional patients had recurrence within the involved lobe (range, 0.1–5.9 years after stereotactic body radiation therapy), resulting in a 5-year primary tumor and involved lobe failure rate of 20%.
The 5-year local-regional failure rate was 38%, of which seven patients experienced a spread of the cancer to nearby lymph nodes or organs (range, 2.8–5.2 years after stereotactic body radiation therapy). Fifteen patients had disseminated recurrence, thus the 5-year disseminated failure rate was 31%. Treatment-related grade 3 and 4 side effects were reported in 15 and 2 patients, respectively. No grade 5 adverse events were reported.
“Historically, when treating early lung cancer with radiotherapy, progression at the site of the primary tumor was the most common failure resulting in suffering and death,” said lead study author Robert Timmerman, MD, Professor and Vice Chair of the Department of Radiation Oncology at the University of Texas Southwestern Medical Center in Dallas.
“The initial results of RTOG 0236 showed very good tumor control; however, many physicians were concerned that treatment-related toxicity would eventually appear, so stereotactic body radiation therapy has not seen widespread use. This long-term analysis confirms that treated tumors did not reappear at the original site; and late toxicity, beyond what was seen in the initial report, did not appear. However, metastatic tumors continued to appear over time in untreated sites likely because those tumors were so small at initial treatment that they were not detected. These 5-year results demonstrate positive tumor control and disprove the misconception that short-course treatment will result in late-appearing, unacceptable toxicities.”
Dr. Timmerman reported receiving a research grant from Varian Medical Systems.
The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
