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Stereotactic body radiation contained early-stage, medically inoperable lung cancer at its site of origin in all but one patient involved in a small clinical trial report.

One of 55 patients had local failure at three years, resulting in a local control rate of 98%, Robert D. Timmerman, MD, of the University of Texas Southwestern Medical Center in Dallas, and colleagues found.

Half the patients were alive and cancer free at three years, and overall survival at three years was 56%. The findings offer a dramatic contrast to the 30% to 50% successful local control with conventional radiation therapy for lung cancer.

"The results of the study confirm that stereotactic body radiation therapy should now be considered standard treatment in early-stage lung cancer patients with coexisting serious medical problems, such as emphysema, heart disease, and stroke," he added. "It also begs the question of whether stereotactic body radiation therapy should be considered in healthier patients with lung cancer who are treated with surgery."

Results of the small Phase II trial preclude the need for Phase III evaluation of stereotactic body radiation in early-stage, inoperable lung cancer, said Stephen Hahn, MD, of the University of Pennsylvania in Philadelphia, moderator of the press briefing.

Offering a more tempered reaction, Anthony Zietman, MD, of Harvard and Massachusetts General Hospital, said stereotactic radiation will not supplant conventional radiation therapy for most lung cancers. Stereotactic radiation therapy is best suited for small, peripherally located tumors, he said.

The findings came from a Radiation Therapy Oncology Group trial that enrolled patients from May 2004 to October 2006. Eligible patients had T1 or T2 lung cancer (primary tumor mass < 3 cm more than 2 cm from the central bronchial tree) and medical conditions that disqualified them from surgery. The median age of the patients was 72, and median follow-up was 48 months.

Radiation therapy consisted of three 20-Gy fractions delivered over the course of one week. Correction for tissue heterogeneity revealed an actual total dose of about 54 Gy. Investigators defined local failure as an increase in lesion size of at least 20% on CT and either a confirmatory biopsy or PET imaging that revealed tracer uptake similar to pretreatment levels.

Analysis of contouring showed that 98% of target lesions and 73% of normal tissue structures were outlined per protocol or with only minor deviations.

Grade 3-4 adverse events occurred in nine (17%) patients, the most common being pulmonary/upper respiratory and musculoskeletal. No treatment-related deaths occurred. Three-year disease-free survival was 48%, and overall survival was 56%. Timmerman said 18% of patients died of metastatic lung cancer.

Source: American Society for Radiation Oncology

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