By Teh Lin, PhD, Associate Professor, Fox Chase Cancer Center
Lung cancer is the second most common form of cancer in the United States and globally with an estimated 2.1 million cases annually and responsible for approximately 1.8 million deaths. Patients with early stage but a medically inoperable lung lesion still had poor tumor control with high mortality rates with radiation therapy. RTOG 0236, ASTRO/ACR guidelines, an earlier phase I trial and RTOG 0915 reported stereotactic body radiation therapy (SBRT) can improve the overall survival rates to the lung cancer. However, the optimal delivery methods to tackle the moving target remains unknown. This radiation oncology group from Japan proposed a brilliant way to better localize the radiation delivered dose to achieve better overall survival and progression-free survival.
Yukinori Matsuo, MD, PhD, from Kyoto University Graduate School of Medicine, Kyoto, Japan, leads a multi-institutional phase II study to evaluate the safety and efficacy of dynamic tumor tracking-stereotactic body radiotherapy (DTT-SBRT) for lung tumors treated 50 Gy in 4 fractions using a gimbal-mounted linear accelerator. This study reports their five-year survival and late toxicities observation.
Forty-eight tumors (median diameter, 23.5 mm; range, 5–47 mm) in 48 patients were targeted for DTT-SBRT. “Overall survival at five years was 51.5% (95% confidence interval [CI], 36.5–64.6%). Progression-free survival and local control at five years were 41.0% (95% CI, 27.0–54.5%) and 92.6% (95% CI, 78.7–97.6%), respectively.” And there were no grade 4-5 toxicities.
This result is quite encouraging. While RTOG 0236 reports the disease free and overall survival at five years were 26% and 40% respectively, Dr. Matsuo’s study indicates that Dynamic Tumor Tracking (DTT) is the key point for the lung SBRT delivery to further improve the treatment outcome. After all, tracking the lung tumor can certainly minimize the target margin and reduce the toxicities and guarantee the target coverage.
Abstract 152 - Long-Term Results of a Multi-Institutional Study of Dynamic Tumor Tracking-Stereotactic Body Radiotherapy for Lung Tumors was presented on October 2, 2023, during the SS 10: Phys 2: Best of Physics session at the 2023 ASTRO Annual Meeting.
