Abortion and breast cancer are the topics that can bring strong emotions in people. The issue of abortion is often associated with personal and political points of view - even without the possible relationship of disease. Breast cancer is the most common cancer among women. It can be life-threatening disease - one that many women are afraid.
2 references to these themes, a lot of emotion and debate. But the study did not find a causal link between abortion and breast cancer.
How hormones affect the breast?
Women risk of some types of breast cancer associated with the level of hormones in the body. Breast cells normally grow and divide in accordance with the level of certain hormones such as estrogen, progesterone, and prolactin. When a woman is pregnant, her body begins to prepare for breast-feeding, changing levels of these hormones. This causes changes in the tissues of the breast.
How can affect abortion hormones during pregnancy?
Concerns about a possible link between abortion and breast cancer has been raised, because abortion is considered to interrupt the normal cycle of hormones during pregnancy. Some believe that this time a woman raises the risk of developing breast cancer.
There are different types of abortion:
* Spontaneous abortion, which most people referred to as miscarriage, is the loss of the fetus up to 5 months (20 weeks) during pregnancy. It is often caused by problems with the fetus or the mother's environment in which it grows.
* Stillborn birth (stillbirth) is generally considered to be the death of the fetus, after 5 months of pregnancy, and even in the uterus (womb).
* Induced abortion is probably what most people believe "abortion." This applies to the medical procedure to end the pregnancy.
All these situations have been investigated to see what impact they might have on women's risk of developing breast cancer later in life.
Studies on abortion and breast cancer
Research problems
Numerous studies have looked at the possible link between abortion and increased risk of breast cancer. But because of the nature of the topic, these studies were difficult to conduct. This may help explain why some of them have reached different conclusions.
Prior to 1973, abortions were banned in most parts of the United States. So, when the researchers asked the woman on previous pregnancies, she may not have been comfortable admitting that she had illegal abortions. Although abortion is currently legal, it is still very personal, private matter that many women do not like to talk about.
Studies have shown that healthy women are less likely to report that they were induced abortions. In contrast, women with breast cancer more accurate data on their reproductive history, because they're looking for your memories that may have contributed to their illness.
The likelihood that women with breast cancer will provide a more complete report on their abortions than women without breast cancer is an example of recall bias. Recall bias as it could lead to research to find links that do not exist
Research, development
Most of the early research, abortion and breast cancer using case-control study design, which are very susceptible to recall bias. In these studies, women with and without breast cancer were asked to report on the recent abortion. Then the researchers compared the frequency of abortions in women with breast cancer (cases) to those women without breast cancer (controls). It is likely that higher rates of reported abortions in cases, breast cancer (compared with control) seen in many of these studies, the findings do not correspond to reality, since the recall bias.
Prospective (cohort) studies, the development of stronger and less prone to bias. In such a study, a group of women who are cancer-free are asked about their past abortions, and then watch for a certain period of time to see if a new cancer occurs. In such a study of all women with cancer free of charge at the beginning, so there is no chance that the existence of the disease will affect their memory of the past, abortion, and their willingness to report past abortions.
Some prospective studies have examined the problem of recall bias by using new techniques to learn about past abortions. For example, a recent study used birth certificates of children born to women with breast cancer to identify women who had abortions. (The number of abortions has been given prior to these birth certificates.) This study found no increase in risk of breast cancer among women whose abortion is accompanied by a live birth.
Recent studies have confirmed that this type of research is likely to play a role that found. Review of previous studies on the subject (see "Results of the study), which covers tens of thousands of women showed that women should be in the prospective studies (which are less prone to bias) does not increase the risk of breast cancer if they have an abortion. Case-control studies, which are prone to bias, indicating a slight increase in risk.
The results of the study
The largest and perhaps the most reliable, one study on this subject was made in 1990 in Denmark, a country with a very detailed medical records for all its citizens. In this study, all Danish women born between 1935 and 1978 (a total of 1.5 million women) were associated with a national registry of abortions and the Danish Cancer Registry. Therefore, all information about their abortions and breast cancer from the roster, was a very full, but not under the influence of recall bias.
After adjustment for known breast cancer risk factors, researchers found that the artificial termination of pregnancy (a) does not affect the overall risk of breast cancer. The size of the study, and how it was done provides good evidence that abortion does not affect women's risk of developing breast cancer.
Other large, prospective study was reported by researchers at Harvard in 2007. The study included more than 100,000 women were between the ages of 29 and 46 at the beginning of the study conducted in 1993. These women were followed until 2003. Again, because they are asked about their reproductive history at the beginning of the study, recall bias is unlikely to be the problem. After adjustment for known breast cancer risk factors, researchers found no relationship between either spontaneous or induced abortion and breast cancer.
Teachers California study also reported more than 100,000 women in 2008. Researchers asked women in 1995 about past induced and spontaneous abortions. Despite the fact that women now are more than 3300 developed invasive breast cancer. There was no difference in risk of breast cancer among the group, which was either spontaneous or induced abortions, and those who had abortions.
What experts say?
In February 2003, the U.S. National Cancer Institute (NCI) held a workshop for more than 100 leading international experts who study pregnancy and the risk of breast cancer. The experts reviewed existing human and animal studies on the relationship between pregnancy and the risk of breast cancer, including the study of artificial and spontaneous abortions. Some of their findings were:
* Breast cancer risk is increased for a short time after the full term of pregnancy (eg pregnancy, which leads to a live birth).
* Induced abortion is not associated with increased risk of breast cancer.
* Spontaneous abortion is not associated with increased risk of breast cancer.
The amount of scientific evidence for these findings was considered "well-established (high level).
The American College of Obstetricians and Gynecologists (ACoG) Committee on Gynecologic Practice also review the available data and published their findings in August 2003. After consideration, the Committee noted that "at the beginning of the study on the relationship between prior induced abortion and breast cancer risk have been inconsistent and difficult to interpret because of methodological considerations. More rigorous recent studies argue against a causal link between induced abortions and subsequent increase in risk of breast cancer. "
The Joint Group on Hormonal Factors in Breast Cancer, based out of Oxford University in England, has recently compiled the results of 53 separate studies conducted in 16 different countries. These studies included nearly 83,000 women with breast cancer. After combining and analyzing the results of these studies, the researchers concluded that "the totality of worldwide epidemiological evidence indicates that termination of pregnancy either spontaneous or induced abortions have no negative impact on women's risk of subsequent development of breast cancer." Again, these experts do not believe that abortion (either induced or spontaneous) cause a higher risk of breast cancer.
Conclusion
The topic of abortion and breast cancer highlights many of the most complex aspects of the study of human populations and how these studies or not to transfer to public health guidelines. The issue of abortion generates passionate views of many people. Breast cancer is the most common cancer and second leading cancer killer among women. Nevertheless, the public is not well served by false alarms. Since 2008, the scientific evidence did not support the idea that abortion increases the risk of breast cancer.