Psychiatrist Francesco Di Leo is cautious in choosing candidates for LSD psychotherapy. Physicians who sense in their cancer patients anxiety, depression or pain that seems unresponsive to painkillers may suggest they talk to Di Leo. But sometimes they neglect to mention he's a psychiatrist working with the mind-altering drug LSD.

"The first problem is how to say you're a psychiatrist without making them feel that -- on top of having cancer -- they're also crazy," Di Leo said. "They may be enraged because cancer treatments aren't working, and on top of it, you're saying they're crazy?

"Or families can get angry at you. You know, 'Don't talk to my mother,' or 'Don't you ever come back here, you're upsetting her.' So you have to pull back immediately if something like that happens.' "

But if the patient and his or her family agree that some emotional help is needed, his next problem is explaining that his work involves LSD.

"Then you have all kinds of reactions," he said. "To mention LSD can be worse than mentioning AIDS. Sometimes the family will say, 'You can't do that, they'll go crazy, they'll jump out the window!' "

But for the three of 10 referrals who decide to try the LSD therapy, many hours of pre-therapy discussion are required. Patients receive a list of 46 types of experiences that others have had under the drug. Pain-killers are reduced to minimal levels so the patient can speak and hear more clearly. Tranquilizers are stopped before the session because they can interfere with the drug's action.

Ideally the treatment takes place in an outpatient setting -- at home or at Di Leo's office -- but it can take place in the hospital room if necessary, even for patients hooked up with tubes and medical equipment.

The session -- which can last up to 12 hours -- begins in the morning. After ingesting the standard 100 to 400 micrograms of LSD (supplied by the National Institute of Drug Abuse), the client lies back on a bed or sofa, dons eyeshades and stereo headphones, and waits 20 minutes to an hour for the drug to take effect.

"At the moment of altering reality, they may get a little terrified," Di Leo said. "They might take off the eyeshades and sit up and say, 'Hey, what's going on?' You may have to hold their hand and tell them, 'It's all right, it's okay, it's part of the experience, so allow it to happen . . . You'll come back here and experience the way it was before. But now's your chance to go into yourself . . . Trust it, you'll come back.' "

The client is discouraged from talking about the onrush of mental images and events, and encouraged to save them for later discussion.

Music from the headphones gives a background continuity and reduces accidental noise interference. Familiar music -- without words, to avoid suggesting specific ideas -- may be played at the start of the session. As the experience intensifies, classical music -- like Vivaldi, Wagner, Beethoven, Bach or choral music -- might be played. As the client "comes down," familiar music again might be used.

After the emotional blitzkrieg LSD can trigger, it is vital to therapy that the family -- who wait in an adjacent room -- take a positive attitude with the subject, Di Leo said.

"You don't want a family member to come in and say, 'What the heck did you do with that stuff? Now you've really messed up your brains,' " he said. "We want them to be very supportive at that point because they can undo a lot of work that's been done if they're negative."

For many patients, it is the first time they are able to talk with their families about impending death.

"Frequently there's this very emotional exchange when the family comes in from the reception room," Di Leo said. "The patient might say something like, 'Hey, I know I'm going to die. But it's okay. Let's let the cat out of the bag. We've been holding this in for so long . . .' "