Is it safe to offer SBRT for a secondary NSCLC after breast or chest wall irradiation many years prior?

I agree with @Dr. First Last. Surgery is preferred here. However, if surgery is not an option or is high risk, I would offer SBRT. I still offer 10 Gy x 5 in this setting because if I do it, I still want to offer the best chance for tumor control (10 Gy x 5 has a BED10 = 100 Gy, the threshold dose)....

Generally speaking, it is safe to offer SBRT for a second primary lung cancer, after initial radical management of a lung or breast cancer that has been treated with primary radiotherapy. In fact, some series have reported repeat lung SBRT in areas of local recurrence, with decent results.

Of course,...

Most of time, it is reasonably safe to deliver SBRT after prior RT to chest wall many years ago. If the lesion is large (>3 cm) and very close to the chest wall (< 5 mm), we would consider 70 Gy in 10 fractions instead of 50 Gy in 4 fractions. With control of the chest wall dose volume constraints (...

It depends. You can use longer fractionations like 5-7 fractions.