Yes, of course knowledge is vital. But we shouldn't speculate on what Ms. Jolie had or hadn't done to arrive at the decision to undergo the double mastectomy. She might actually be very pro-alternative treatment approaches but after full consideration, from all angles, she chose this drastic measure based on *her personal circumstance*. I don't believe she is promoting double mastectomies on a wide scale to prevent breast cancer. For all I know the genetic markers she has is fairly rare.
My last word on all this: we are talking about risk. Ms. Jolie was staring at a number: 87%. Obviously she believed she could not mitigate this risk, or at least not enough to make her feel comfortable in keeping her breasts. No one on this forum should denounce her decision since we don't have all the facts.