The non-news of the day. This issue was generated by anti-abortion types who started what can only be called a rumor about an association of cancer and pregnancy termination. The issue is difficult to analyze because of the high rate of 1st term abortion (spontaneous and other) and the long lag time between supposed events and disease development. This appears to be a definitive study on the subject–there is no risk of breast cancer from pregnancy termination.
However, what has been long known known about breast cancer and sexual activity is that nuns have a higher rate of the disease.