Stereotactic Body Radiation Therapy for Tumors in the Thorax

Stereotactic Body Radiotherapy (SBRT) for tumors in the thorax is a relatively new therapy in the United States, but has been used extensively in Japan for more than 10 years. This protocol seeks to enroll patients in three broad categories based on histology and clinical scenario: primary therapy for non-small-cell lung cancer (NSCLC), primary therapy to thoracic metastases, and retreatment of previously irradiated tumors or lung.

Primary lung tumors

Several studies have been published describing the utility of Stereotactic Body Radiotherapy (SBRT) for primary untreated lung tumors. In the United States, the most influential has been the experience of Robert Timmerman at the University of Indiana (7). They enrolled 37 patients in a dose escalation trial of SBRT for T1 N0 and T2 N0 patients with Non-small-cell lung cancer (NSCLC). The trial began with 24 Gy given in 3 fractions and escalated to 60 Gy given in 3 fractions. Dose limited toxicity (DLT) was defined as any grade 3 pulmonary, esophageal, cardiac, or pericardial toxicity, or any grade 4 toxicity that was ascribed to the protocol treatment using the Common Toxicity Criteria from the National Cancer Institute. The maximum tolerated dose (MTD) was defined at dose where less and 2 of 5 enrolled patients experienced DLT. The MTD was not determined by this trial as this criteria was not met in the enrolled patients. Of the 37 patients, 2 experienced Grade 3 toxicity. One patient experienced pneumonitis and other patient experienced hypoxemia. Both patients responded to therapy and made full recoveries. There were no long term complications reported from the treatment at a mean follow-up of 15 months.