RCOG- Abortion and Breast Cancer

Royal College of Obstetricians and Gynaecologists 11 August 2000

Abortion and Breast Cancer
In March 2000 the RCOG published an Evidence Based Guideline on "The Care of Women requesting Induced Abortion". Induced abortion is one of the most commonly performed gynaecological procedures in Great Britain. Around 180,000 terminations are performed annually in England and Wales and around 12,000 in Scotland. At least a third of British women will have had an abortion by the time they reach the age of 45. The Guideline Development Group view induced abortion as a healthcare need. The aim of the guideline was to ensure that all women considering induced abortion have access to a service of uniformly high quality. The guideline summary is available on the RCOG website (www.rcog.org.uk).

The guideline includes many aspects of abortion care including the provision of information for women about potential complications. One these recommendations reviews the evidence of the association between breast cancer risk and abortion. (shown below)

The RCOG wishes to reassure women who have had an abortion or who have breast cancer that the research evidence on this question to date is INCONCLUSIVE. The association found in some studies has not been found in others of equal quality. Indeed studies based on the linkage of national registers on induced abortion and breast cancer which are less open to bias than case-control studies which rely on recall of subjects have not shown any significant association.
Breast cancer risk: available evidence on an association between induced abortion and breast cancer is inconclusive. (Grade B)

Two carefully conducted meta-analyses examining the relationship between induced abortion and subsequent breast cancer have been published. The two reviews have reached different conclusions about the nature of any association. The validity of case-control studies of abortion and breast cancer have been seriously questioned because of the evidence that there is a significant difference between cases and controls in their willingness to reveal whether or not they have had an abortion. Studies based on the linkage of national registers on induced abortion and breast cancer are less open to bias than case-control studies relying on recall of subjects.

Two such studies have not shown any significant association.
A recent review from Grimes' group has highlighted the differences in validity of the various available studies. When only those studies least susceptible to bias are included, the evidence suggests that induced abortion does not increase a woman's risk of breast cancer in later life.