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.
However since it is socialized medicine in Denmark, they keep records on every patient. They know who has had an abortion and who has had breast cancer. It is all in the records there. They don't have to interview the patient and therefore there will be no "recall bias."
This "cohort" study was of 1.5 million women. It was a significant study. Since the records were already kept by the time of the study, there was no way the doctors could have known in advance for 60 years to "lie" into records so as to bias this future study.
In fact, no cohort study has ever found a link between abortion and breast cancer. Only the methodology flawed "case-control" studies have found such a link, and it has been shown that this is solely due to recall-bias -- where healthy women underreport their abortion histories as compared to women who know they have breast cancer.