Dad has stage 1 Lung Cancer - Need advice on non srugical options

My father is 71 and has been diagnosed with Small Cell Lung Cancer. The scans have shown no changes in the last few months so it is very encouraging that we caught this early. My father does not want to do surgery so we are looking into SBRT as a non surgical option. Anyone have a pos/neg experience to share. He is at Kaiser so we are looking at Kaiser Roseville and San Francisco, although we are based in LA.

Also getting second opinion at UCLA.

Any help is greatly appreciated!