It is a known medical fact that women who use oral contraceptives and/or have had an abortion are at a higher risk of breast cancer.
The Susan G. Komen Foundation contributes large sums to Planned Parenthood, the leading dispenser of oral contraceptives and the leading provider of abortions. Many people are still - for reasons unknown to me - unaware of this; consequently, if you help fund the Komen Foundation you are also funding the causes of breast cancer. It makes little logical sense, I know.
What, then, is a person of good will to do who wants to help eradicate breast cancer? Phat Catholic offers a few good suggestions and alternative places to donate money.