Not to cut.
The Study: RTOG 0618 is a phase 2 trial of SBRT for operable NSCLC. Tumors were peripheral and ≤5 cm without PET evidence of nodal disease (≤cT2aN0). Patients had to have FEV1 and DLCO > 35% of predicted, PaO2 > 60 mmHg, and PaCO2 > 50 mmHg. In other words, they had to be good surgical candidates. Radiation consisted of 54 Gy in 3 fractions on nonconsecutive days. It’s important to note here how tumor control was defined. First, the largest axial diameter (LD) on the planning CT scan and the maximum SUV of the tumor on pretreatment PET scan were recorded. After treatment, the LD is recorded at each interim CT. An increase in the LD >20% prompted either a PET or biopsy. If the PET SUV was similar to pretreatment SUV or if biopsy was positive, it was defined as a local tumor failure. The authors pre-defined acceptable control as 90%. Among 33 enrolled patients at 4 years, local tumor control was an impressive 96% and even loco-regional control was 88%. Disease-free and overall survival rates at 4 years were both around 55%, though, indicating potential need for the addition of systemic therapy. The rate of G3 toxicity was 15% with no G4/5 toxicity. Next up, neoadjuvant or adjuvant immunotherapy in this population.
Bottom Line: We now have prospective evidence that SBRT for operable patients with early stage NSCLC achieves excellent tumor control (96%) at 4 years with low rates of toxicity. | Timmerman, JAMA Oncol 2018