The oncologist who will provide a second opinion will rely on a detailed referral letter and the copies of all relevant exams, such as biopsies, blood results or CT scans. Therefore, to proceed with a second opinion, a referral will be required, ideally from a medical professional currently involved with your care.
This referral is often from the current oncologist (at your request), but alternatively it may also be from your GP. A referral from the current oncologist is preferred, since the GP relies on the information passed on from the oncologist, and they may not have all your relevant test results. Some GPs may not feel they have enough information to request a second opinion on behalf of a patient. Sometimes the oncologist doing a second opinion may also need additional information, so it helps if they are directly in contact with your current oncology team.