In Reply: In response to Drs Rusthoven and Pugh, several prospective series have shown a rather low rate of regional recurrence after SBRT, perhaps different than would be predicted based on larger surgical series defining pathological tumor involvement within nodes of initially clinically staged patients.1,2 A number of possible explanations have been offered, including a theory regarding immune stimulation after tumor ablative SBRT as suggested by Rusthoven and Pugh.3 Counter to this argument, however, is the higher rate of distant dissemination observed in our study. If the primed immune system is capable of eliminating micrometastases in the regional lymphatics, it is not clear why it would be less effective in distant organs.
Timmerman R. Stereotactic Body Radiation Therapy for Inoperable Lung Cancer—Reply. JAMA. 2010;303(23):2354-2355. doi:10.1001/jama.2010.778