My 85 year old father has had two biopsies of a small lung tumor over the last 6 months after it was detected during a CAT Scan. Both biopsies were negative. He is about to undergo Cyberknife treatments for the lung tumor. My father lives in another state and I couldn't convince him to get a second opinion and he couldn't explain to me the rational for going ahead with the Cyberknife treatment. Is it typical for cancer treatments to be done without a positive biopsy?View Thread