A recent study published in the Journal of the National Cancer Institute indicates that pregnancy does not incur a greater risk of relapse for survivors of breast cancer. The safety of pregnancy for women with history of breast cancer has remained a controversial topic for many years, especially in cases of estrogen-receptor (ER) positive breast cancer. In these cases, hormones can promote the growth and spread of breast cancer so, as hormone levels change during pregnancy, it was thought that breast cancer would be more likely to recur in survivors of ER positive breast cancer during pregnancy.
The study compared breast cancer survivors who became pregnant with those who did not become pregnant over an average period of 7 years. The study tracked the recurrence rate of breast cancer and found that those who became pregnant did not experience a greater rate of recurrence, even in cases of ER positive breast cancer.
These findings show that pregnancy does not increase the risk of breast cancer recurrence, alleviating fears that pregnancy poses a greater risk to breast cancer survivors. The study notes that fears among physicians and patients may be a factor in the high rate of abortion among women who have a history of breast cancer.
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Matteo Lambertini et al, Long-term Safety of Pregnancy Following Breast Cancer According to Estrogen Receptor Status, JNCI: Journal of the National Cancer Institute (2017). DOI: 10.1093/jnci/djx206