The Love Story star revealed he had been diagnosed with stage two prostate cancer last month (Apr12), but assured fans he would bounce back from the health crisis as the disease had been ""detected early"" and the prognosis was ""positive for a full recovery"".
He was due to appear on U.S. breakfast show Today on Monday (30Apr12) to advertise his new tell-all tome about his longtime love affair with Farrah Fawcett, Both Of Us: My Life With Farrah, but O'Neal had to pull out at the last minute after falling ill.
He returned to the New York-based programme on Tuesday (01May12) and explained that he had suffered a panic attack moments before going on air on Monday - although he's unsure why.
He said, ""I don't know what was wrong. Terror, perhaps? I just broke out into a terrible sweat, you wouldn't have wanted me! So I went home and went to bed, and I feel better now. They (doctors) said that's what it was (a panic attack), but I had never had one before... I'm OK now.""
The 71 year old, who previously battled leukaemia, went on to confess he's yet to begin the exhaustive process to treat the cancer and try to put a stop to the spread of the disease.
When asked how he was feeling, he told host Matt Lauer, ""Inundated with the disease, actually. I'm working to cure it... I've chose (sic) to go to you first, and then I'll do something about it when I go back to California.""