14 DAY TRIAL // A new Harvard research has found no link between a woman's risk of developing breast cancer and abortion or miscarriage. The National Cancer Institute, part of the NIH, has long declared that the link between breast cancer and abortion is false.
This did not impede many disinformation campaigns, which succeeded in forcing different state legislatures (Texas, Minnesota and Mississippi) to ask that women should be told they are increasing their risk of breast cancer by having an abortion.
Neither induced abortion nor miscarriage appears to influence breast cancer risk in the premenopausal women, a new U.S. study concludes.
"In this cohort study of young women, we found no association between induced abortion and breast cancer incidence and a suggestion of an inverse association between spontaneous abortion (miscarriage) and breast cancer incidence during 10 years of follow-up," said the team from Brigham and Women's Hospital, Harvard Medical School and the Harvard School of Public Health, Boston.
The analysis was made on information gathered from almost 106,000 pre-menstrual women subjects, aged 29 to 46, involved in the Nurses' Health Study II, which started in 1993. Over 16,000 experienced an induced abortion during their lives and almost 22,000 had a miscarriage. During the period of the study (1993 to 2003), 1,458 new cases of breast cancer were detected inside the pool. The data analysis found no connection between abortion, miscarriage and breast cancer.
"We observed associations in two subgroups, an association between induced abortion and progesterone receptor-negative breast cancer (cancer that does not respond to the hormone progesterone) and an inverse association between spontaneous abortion before the age of 20 years and breast cancer incidence."
These secondary links were found in samples that were too small to have great statistical power.
"No obvious mechanisms can be provided for these subgroup findings; thus, chance has to be considered as a possible explanation," wrote the researchers.