Abortion is an issue that can bring out strong feelings in people. These feelings are often linked to personal, religious, and political views that may have little to do with any connection to a disease like cancer. Linking these topics creates a great deal of emotion and debate. But scientific research studies have not found a cause-and-effect relationship between abortion and breast cancer.
Breast cells normally grow and divide in response to hormones like estrogen, progesterone, and prolactin. Breast cancer risk can be affected by a number of things that alter these hormone levels.
For example, women who have more menstrual periods over their lifetime because their periods start earlier, they go through menopause later, or they never get pregnant have a slightly higher risk of breast cancer. The use of some types of hormones for birth control or to control the symptoms of menopause can also increase breast cancer risk slightly although this risk goes down over time after hormone use is stopped. On the other hand, breastfeeding might lower breast cancer risk slightly.
Women who have a full-term pregnancy before age 20 have a lower risk of breast cancer than women who never have a full-term pregnancy or who have their first full-term pregnancy after the age of 30 or The risk of breast cancer also goes relationship between breast cancer and abortion as the number of full-term pregnancies goes up.
Still, a full-term pregnancy after age 30 is linked to a higher risk of breast cancer than never giving birth. The reasons for these changes in risk are not entirely clear, relationship between breast cancer and abortion. We do know that hormone levels typically change a lot during relationship between breast cancer and abortion. Some of these changes cause cells in the breast to mature, to help prepare to produce milk for breastfeeding.
This might affect the tendency for these cells to become cancerous. Concern about a possible link between abortion and breast cancer has been raised because abortion is thought to interrupt the normal cycle of hormones during pregnancy.
Researchers have looked at the possible link between abortion and breast cancer for many years, but this has been a difficult area to study. The most reliable way to know if something causes cancer would be to do a randomized study.
Whether someone is in relationship between breast cancer and abortion exposed or non-exposed group would be chosen at random. As long as the 2 groups were similar to start with in terms of risk factors for cancer, relationship between breast cancer and abortion, any difference in cancer risk between the 2 groups would likely be because of being exposed to the possible carcinogen. This is especially true for effects of abortion. Instead, to look at the effects of abortion on cancer risk, we have to use observational studies.
These kinds of studies gather information about the people in them, often by asking questions or looking at medical records. Then the researchers try to see if certain factors or exposures are linked to certain outcomes, relationship between breast cancer and abortion.
There are different types of observational studies:. Often, this is done by asking the people in the study many questions about what they did or were exposed to many years ago.
This is called a retrospective design. One problem with retrospective studies is that it can be hard to remember what you did long ago. This might mean that the study could miss a link. But a bigger problem with this kind of relationship between breast cancer and abortion is that people with a disease like cancer often think very hard about what they may have done in the past that could have contributed to their getting cancer.
They are also more likely to tell the researchers about things vitamin d and sun they would otherwise feel was too personal or embarrassing to mention — like abortion. This is called recall biasand relationship between breast cancer and abortion can lead to a study finding links that may not really exist.
A cohort study is another kind of observational study, but it is less prone to recall bias. These people are then watched over time, often being asked every so often about possible risk factors and exposures. They can see if the people who got the disease were more likely to have had a certain exposure.
Since none of the people had the disease like cancer at the start of the study, there is no chance that having the disease would have influenced their memory or their willingness to report things in their past like abortion. Because cohort studies follow people forward in time, they are called prospective studies. Researchers generally consider the conclusions from cohort studies to be stronger than those from case-control studies.
Some case control studies try to get past recall bias by using information that was collected before the person had cancer. They may use medical records or birth certificate registry information, for example. Because these studies use information collected before the cancer, they are also considered prospective studies, relationship between breast cancer and abortion.
The results of studies looking at the possible link between breast cancer and induced abortion often differ depending on how the study was done. Cohort studies and studies that used records to determine the history of abortions have not found an increased risk. Some case-control studies, however, have found an increase in risk. The largest, and probably the most reliable, study on this topic was done during the s in Denmark, a country with very detailed medical records on all its citizens.
Relationship between breast cancer and abortion this study, relationship between breast cancer and abortion, all Danish women born between and a total of 1. All of the information about their abortions and their breast cancer came from registries — it was very complete and was not influenced by recall bias.
After adjusting for known breast cancer risk factors, the researchers found that induced abortion s had no overall effect on the risk of breast cancer. Another large cohort study was reported on by Harvard researchers in This study included more thanwomen who were between the ages of 29 and 46 at the start of the study in These women were followed until Because relationship between breast cancer and abortion were asked about childbirths and abortions at the start of the study, recall bias was unlikely to be a problem.
After adjusting for known breast cancer risk factors, the researchers found no link between either spontaneous or induced abortions and breast cancer. The California Teachers Study also reported on more thanwomen in Researchers had asked the women in about past induced and spontaneous abortions.
There was no difference in breast cancer risk between the group who had either spontaneous or induced abortions and those who had not had an abortion. A European cohort study that published findings in followed overwomen from 9 countries over an average of more than 6 years.
This study found no link between induced abortion and breast cancer risk. A French cohort study of more thanwomen, published inalso found no link between induced abortion and breast cancer risk. A Danish study of over 25, women who had at least one full-term pregnancy found no link between induced abortion and breast cancer risk over 12 years of follow-up. Other cohort studies have looked specifically at the possible link between abortion and breast cancer in African-American women and in women who are at increased risk of breast cancer because they have mutations in the BRCA genes.
These studies also did not find a link. Inthe Collaborative Group on Hormonal Factors in Breast Cancer, based out of Oxford University in England, put together the results of many studies that looked at abortion and breast cancer risk. It looked at both cohort and case-control studies. Some other retrospective studies published since then have also found an increased risk, including a case-control study of about 1, women from China published in and a case-control study of women in Iran published in But some recent case-control studies have not found a link, including a study of about women from Serbia published in In fact, women in this study had a lower risk of breast cancer.
Induced abortion brings up many strong feelings in people, so it is often hard to study its long-term effects. Beforeinduced abortions were illegal in much of the United States. So when researchers asked a woman about past pregnancies, she may not have felt comfortable saying that she had an abortion.
Even though abortion is now legal, it is still a very personal, private matter that many women do not like to talk about. This means that many women might not report having an abortion if asked for a study.
In contrast, relationship between breast cancer and abortion, women with breast cancer are more likely to accurately report their reproductive histories, including a history of having an abortion. Still, not everyone agrees that this is the reason that the different types of studies conflict. In general, relationship between breast cancer and abortion, though, when prospective and retrospective studies conflict, experts generally accept the results of the prospective studies over the retrospective studies.
Several groups of sphenopalatine and lidocaine and cpt have looked at the available studies on the possible link between abortion and breast cancer.
The experts reviewed human and animal studies that looked at the link between pregnancy and breast cancer risk, including studies of avon naturls antibacterial hand gel and spontaneous abortions. Some of their findings were:, relationship between breast cancer and abortion. More rigorous recent studies demonstrate no causal relationship between induced abortion and a subsequent increase in breast cancer risk. Inthe Collaborative Group on Hormonal Factors in Breast Cancer, based out of Oxford University in England, put together the results from 53 separate studies done in 16 different countries.
These studies included about 83, women with breast cancer 44, in prospective studies and 39, in retrospective studies. Relationship between breast cancer and abortion the results of the retrospective studies showed a small increase in risk, the prospective studies found a small decrease in risk.
The topic of abortion and breast cancer highlights many of the most challenging aspects of studies of people and how those studies do or do not translate into public health guidelines. The issue of abortion generates passionate viewpoints in many people. Breast cancer is the most common cancer in women aside from skin cancer; and breast cancer is the second leading cancer killer in women. Still, the public is not well-served by false alarms.
At this time, the scientific evidence does not support the notion that abortion of any kind raises the risk of breast cancer or any other type of cancer. Induced Abortion and Breast Cancer Risk. J Natl Cancer Inst. Breast cancer and abortion: Collaborative reanalysis of data from 53 epidemiological studies, including 83, women with breast cancer from 16 countries. Induced abortion and breast cancer among parous women: A Danish cohort study.
Acta Obstet Gynecol Scand. Spontaneous and therapeutic abortions and the risk of breast cancer among BRCA mutation carriers. Incomplete pregnancy is not associated with breast cancer risk: The California Teachers Study. Abortion and breast cancer: