I don't know which moment was the most surreal. Was it the sudden break from the network news discussion of colon cancer and diet to the commercial for high-fiber breakfast cereal?

Or was it the moment when the doctor took out the colonoscope in all its glory and showed a television audience precisely how his colleagues looked around inside the president?

Or was it during the press conference when another doctor told the media and the entire nation that the president's "bladder catheter has been removed, and he's successfully returned that function to normal."

The choices abound. There were all sorts of strange highlights in the coverage of presidential cancer. By any definition, there was no privacy left to the president. Occasionally it sounded as if someone had done a good-taste-ectomy on the entire proceedings.

I started to be grateful for small lapses. At least there was no videotape of the operation (I don't think). At least the colonoscope being brandished about on the tube was not the same one used on the president. By the time the man from the cancer society told ABC's Dr. Timothy Johnson how grand it was that we could now use the words blood and stool on the air, I was ready to dissent.

But to my own surprise, I think I agree. With allowances for this excess ardor on the part of the media and a bit of obtuseness on the part of the medical profession -- doctors tend to use phrases such as "the villous adenoma confined to the cecum of the bowel" -- this increasing frankness about disease has been part of a healthy process.

The rotating star system, the disease- of-the-month club, may not be the educational ideal of the public health establishment. But it does offer a crash course to an interested public. When Betty Ford had a mastectomy, breast cancer made every news magazine cover. It's fair to say that she prompted more checkups than a cancer society campaign. She saved lives.

In the same way, the number of people who knew about colon cancer -- second only to lung cancer -- has risen exponentially in seven days. Now, people who couldn't even point to the colon on an anatomy chart may know a Dukes A from a Dukes C. More important, they may seek treatment.

This is not to suggest that Reagan's illness is a great boon, a national service. Cancer is hardly a social value. But dealing with it, directly and completely, is.

Reagan's doctors opened the press conference Monday with the matter-of- fact words, "The president has cancer." Fifty years ago, 25 years ago, doctors might not have told even the patient himself. They would have told the country only if the leader were about to die or to resign.

We are not all that far removed from the era when people could barely say the word "cancer"; they had to whisper it. There was some primal fear that the mysterious disease could be transmitted from mouth to ear. Cancer was the "c- word," which was equated with the "d- word": death.

But what is most notable is that this c-word, the diagnosis, did not elicit mass anxiety. The stock market didn't fall, it rose. People didn't huddle into corners talking about President George Bush. Chalk it up to public relations if you like. Chalk it up to bulletins about the president's "spectacular" postoperative course or his much- touted constitution, or to his courage.

Or chalk it up, in part, to growing honesty and understanding about the disease. The information about cancer has made it easier for us to speak frankly about it, and the frankness in turn has reduced the terror. We seem to have learned, finally, that cancer isn't one illness and a universally fatal one at that. It's many with even more varied futures.

In this most prominent case, the doctors gave good odds to the president and the media gave them in gory, complete and, therefore, believable detail. Having his innards discussed in public is a fair enough price for public reassurance.

With luck, the president will, like most cancer patients, go back to work. The change in our attitudes toward cancer will make that a lot easier. His own attitude is sure to make it easier for the next person with the same diagnosis.

As for luck, his is likely to hold. After all, the president's surgeon has a hobby. He's an amateur magician, accomplished at pulling things out of a hat.