Why, might you ask would they leave out the very ones who may show the most evidence in the here and now? "...women with breast cancer are more likely to accurately report their reproductive histories because they are literally searching their memories for anything that may have contributed to their disease." Because they will be accurate??? Instead of studying only Beast Cancer Patients they study only Cancer Free Patients.
Umm, you have completely misunderstood what they were saying. They were explaining "recall bias." Nowhere did they say they left out of the statistics woman who actually did have breast cancer (that would be silly anyhow.)
What they are saying is that they STARTED studying cancer-free women and then followed up on them for years and measured NEW cancers against their previous answers.
Then if a breast cancer victim suddenly changed her story and admitted an abortion, they could compare it to her previous answers when she was cancer free.
Of course they didn't eliminate women with breast cancer, they just eliminated the possibility of recall bias by pre-screening future breast cancer women.
Is there something about that you don't understand???
Re-read your Study. They are refuting the Studies that include current Cancer because of re-call-bias. Still, like I said. Using this type of study, with the controls being no current cases of Cancer, can be effective. IF and Only IF you follow the pathology of the disease (among other things). This study cannot be used until the entire case group has completed the Cycle. Because current Cancer can be caused by many different things and as far back as 40 + years this study cannot be complete until most or all the women involved die. They chose a long term, un-completed study to prove a point they do not have.