Stereotactic Body Radiotherapy for Larger Lung Tumors
Posted: Friday, December 18, 2020
Andreas Rimner, MD, of Memorial Sloan Kettering Cancer Center, New York, and colleagues designed a study to determine the maximum tolerated dose of stereotactic body radiotherapy for patients with larger (> 3 cm) inoperable, early-stage non–small cell lung cancers (NSCLCs). This treatment is standard of care for patients with this type of cancer, but tumors smaller than 3 cm are often overlooked for these trials. The investigators presented their results, which suggest 50 Gy in five fractions as the maximum tolerated dose, during the virtual edition of the 2020 American Society for Radiation Oncology (ASTRO) Annual Meeting (Abstract 2220).
A total of 34 patients were recruited: 9 were in the dose-escalation group (cohort A), and 25 were in the dose-expansion group (cohort B). Stage one involved a 3+3 dose escalation with either 40, 50, and 60 Gy in five fractions. After stereotactic body radiotherapy was performed, adjuvant platinum-based chemotherapy was administered.
Of the 34 participants, 32 had tumors greater than 3 cm, and 14 had tumors greater than 5 cm. A total of 77% of patients in cohort A completed a minimum of two cycles of adjuvant chemotherapy. In cohort B, two patients experienced grade 2 radiation pneumonitis; five patients had grade 3 toxicities, including one with fatigue and dyspnea, two with dyspnea, and two with chest wall pain. No grade 4 or higher toxicities were reported.
At the median follow-up of 18.3 months, 1- and 2-year progression-free, distant metastasis–free, local failure–free, and overall survival rates were 58.4% and 42.7%, 80.5% and 60.3%, 83.9% and 76.3%, and 85.3% and 63.2%, respectively. Grade 3 radiation pneumonitis occurred in three patients who received 50 Gy for five fractions, and therefore this was the maximum tolerated dose.
In the future, a phase II study will assess whether these patients, who are at high risk for disease progression, might benefit from adjuvant immunotherapy.
Disclosure: For full disclosures of study authors, visit redjournal.org.