Just how powerful IS positive thinking?

Dr. Barry Boyd sees a glimmer of hope on the horizon. An oncologist and director of nutrition and cancer for the Yale Health System, Dr. Boyd says that some preliminary studies show that how patients deal with stress may - just may - influence some cancer outcomes.

"For some individuals, I believe that we will identify hope and attitude as influencing tumor behavior," he said.

"I think there is a part of attitude that may play a role, and we're still trying to understand that," said Dr. Boyd. "Working to build hope and build optimism may, in some individuals, change the biology of their cancer."

But all of the medical experts we spoke to agreed on one thing: There is a danger to the relentless promotion of positive thinking as a means to ward off the inevitable.

"I think there's a ton of pressure based on the belief that if they're positive that they'll live longer," said Coyne. "And then the downside of that is that if they deteriorate and they ultimately die of cancer, that they are somehow left being blamed: If only they had been more positive.

"And I think that's a terrible burden for a dying person to assume," he said.

But there's no talking survivors like Mark Herzlich out of it. For them, mind really does matter:

"All I know is that, for me, that mental toughness and positive thinking helped immensely."

For more info: