I Just Found Out My Lung Cancer Came Back After

I just found out my lung cancer came back after four years. I had upper rt. lobe removed with aggressive chemo and radiation in 2012. Had a pet scan yesterday. Tumor in left lung near aorta. my onocologists said it will be hard to do a biobsy. I see a pulmonary doctor this coming week. They are talking about targeted radiation. I am 63 and other than the cancer my health is good. I do not know what to do.