Study Says, No Relation Between Incomplete Pregnancy And Breast Cancer

A new large study has found that there is no link between incomplete pregnancy such as induced abortion and risk of developing breast cancerdefine.

Earlier studies on incomplete pregnancy and development of breast cancerdefine suggested that induced abortion might increase risk but this new study will put an end to all such speculations.

The researchers from the City of Hope Comprehensive Cancer Center in Duarte, California conducted the large study.

In 1994, a study was published in the Journal of the National Cancer Institute, NCI in which the lead researcher, Janet Daling revealed that among female who had been pregnant at least once, the risk of breast cancer in those who had experienced an induced abortion was 50% higher than among other women.

Lead author, Henderson and his team wrote in the journal Contraception, “Public concern regarding the relationship between induced abortion and breast cancer risk continues to be voiced despite the mounting evidence that no association exists,".

They add: "Much of the data prompting this concern came from case-control studies, many of which may have been affected by bias or design flaws,” reported Medwire News.

The researcher said that there are two main mechanisms hypothesized to form the basis of the possible association between incomplete pregnancy and breast cancer risk. These women don’t have as much long-term protection against breast cancer as they would from full term pregnancies. Also, breasts of women are exposed to high hormone levels of early pregnancy and then don't benefit from the terminal cell differentiation of late pregnancy, possibly making them more vulnerable to cancer causing chemicals.

The team looked at the data of 109,893 women enrolled in the California Teachers Study, CTS (1995-96) baseline questionnaire, where they were asked to fill the detailed questions about pregnancy history, including incomplete pregnancy.

The researchers did follow-up for nine years and found that 3,324 women from the study were diagnosed with incident breast cancer up to 2004.

Henderson and colleagues used Cox multivariable regression and said that they did not fnd statistically significant association between any measure of incomplete pregnancy and breast cancer risk.

They revealed that those women who had induced abortion at first pregnancy didn’t have any increased risk for breast cancer. Secondly, women who had full term pregnancies or females who never went on to give birth were also not at any risk of developing breast cancer. And, if a woman had miscarriage in a first pregnancy, it did not increase her risk for breast cancer in either of these groups.

Henderson and team said their results are compatible with those from a recent large scale study of nurses, the Nurses Health Study II. They said, "Our results provide further, strong evidence that neither induced abortion nor miscarriage is associated with breast cancer risk and may help to resolve any remaining uncertainty as to whether such a relationship exists."