I have O- blood which is in high demand as the Universal Donor. I was told that I could not donate because I had a tumour on my Thyroid back in 1996. Which once removed was not even cancerous. I had to go see a second doctor to have him sign off on it during the interview. I have donated blood many, many times since then for the Red Cross back home. But for some reason they wouldn't take it here. I'm in great health and that was almost 20 years ago now.