We spoke to Dr. Len Lichtenfeld, deputy chief medical officer at the American Cancer Society, to put this study in perspective for the everyday smoker.

CNN: Simple test may determine smokers' lung cancer risk

"To prove that a targeted therapy even worked was incredible a few years ago, " says Len Lichtenfeld, deputy chief medical officer of the American Cancer Society.

FORBES: Magazine Article

However, the potential risks may be acceptable to women who have no other options, said Dr. Len Lichtenfeld, deputy chief medical officer for the American Cancer Society.

CNN: New late-stage breast cancer treatment approved

"Many people are confused by the conflicting messages, " says Len Lichtenfeld, deputy chief medical officer for the American Cancer Society, which suggests getting D from supplements, not the sun.

WSJ: Vitamin D to Defend Against Disease