For as long as I have heard the claims that abortion contributes to breast cancer, I have also heard the counterargument that the apparent link really is nothing more than the fact that abortion prevents the breast-cancer reducing effect of a pregnancy (i.e. a pregnancy ending in birth decreases the risk of pregnancy in a way that a pregnancy ending in abortion does not - although I am assuming this is only known for early-term abortions). So having abortion is no more risky than not getting pregnant in the first place.
Now, according to WorldNetDaily, there is evidence that there actually is a link - but it has been covered up. Obviously, I am a little skeptical of WorldNetDaily, because on the Iraq issue they have been a little too credulous of any report saying that things are going wonderful, and in general seem to be a fount of conspiracy theories that support war or suggest that mass-killing or ethnic cleansing is a morally-acceptable way to solve the Middle East's problems.
But, I have linked to this article (click on "according to WorldNetDaily") so you can read it yourself and see what you think.
That is all.