Hi Anita,
My SSDI claim was approved in less than 30 days also. I am in the regulatory affairs business so I was very careful to review ALL of the filing requirements and bring in all of the supporting documentation. I didn't bring in any letters from the doctor - just actual medical records, i.e., actual diagnosis, scan results, lab tests, anything to validate that this was an actual experience. This is key. If you just show up at the social security office with no documentation - good luck! My claim was forwarded to the State of California which did the actual investigation. I don't think they really care about the prognosis. Your claim is renewed or reviewed periodically. If there is a change, then you are required to report. Cancer fatigue was the justification. It was a cookie cutter. It is hard to be functional at anything when you are asleep or weak most of the time!