Commentary by: Dr Justus Apffelstaedt, specialist surgeon with an interest in breast, thyroid and parathyroid health as well as soft tissue oncology

Q&A: Could your birth control device or medication be increasing your risk of Breast Cancer?

Women living in the 21st century are blessed with many modern medical options our female ancestors would be envious of, with birth control being one of the first that comes to mind.

Many women opt for hormonal birth control methods such as the pill, patch or progestogen-releasing Intrauterine Devices (IUDs) due to the numerous lifestyle and medicinal advantages associated with them; including effective pregnancy prevention, reduced menstruation and known links to a risk reduction of ovarian, endometrial and colon cancers.

But could your birth control device or medication be increasing your risk of breast cancer?

An observational population-wide cohort study conducted in Finland and published in Obstetrics & Gynecology in August 2014, made startling links between the use of progestogen containing IUDs, such as the popular Mirena, and an increased risk of developing breast cancer. The study collected data from 93,843 Finnish women between the ages of 30 to 49 years old, who, from 1994 – 2007 had received a progestogen-releasing IUD. The resultant database was then linked to the Finnish Cancer Registry data in order to compare the incidence of cancers from progestogen-releasing IUD users with cancer incidences in the general population.

As the Mirena and other hormone-releasing IUDs are popular and effective forms of birth control, Dr Apffelstaedt extrapolates below how women can utilise the information from this study to make their own informed decisions about hormonal birth control method choices.

1. Did this study find links between hormone-releasing IUDs and breast cancer?
Yes, the Cancer Risk in Women Using the Levonorgestrel-Releasing Intrauterine System in Finland study published in Obstetrics & Gynecology (August 2014) did find links between hormone releasing IUDs and breast cancer. The risk of ductal carcinomas (the most common form of breast cancer which accounts for approximately 80% of all breast cancers ) as well as lobular carcinomas (which constitutes approximately 10% of all breast cancers ) increased. The study states, “the finding of an increased standardized incidence ration for breast cancer after 5 or more years of follow-up may reflect causality between extended progestin exposure and cancer risk, but the results should be interpreted with caution in light of the limitations of the study .”

2. What are the key insights I should note from this study?
The most important points to consider are:
• The breast cancer risk is time dependent and only increases after 5 years of using a hormone-releasing IUD.
• If you are above the age of 40, even if you have no significant risk factors such as cancer in your family, you should go for mammographic screening.
• If you have breast cancer in your family, speak to your gynaecologist about exploring non-hormonal contraceptive options.
• There is currently no concrete data on whether removing the device will return the risk profile to normal. While the risk may subside, it will still remain elevated in comparison with pre-insertion levels.

3. I have a progestogen-releasing Intrauterine Device (IUD) – why shouldn’t I panic?
There’s no need to schedule an emergency appointment to have your IUD removed.

Any form of medical intervention carries risks and benefits which one needs to consider holistically. Does one trade-off of a small increase in breast cancer risk versus the lifestyle benefits these devices offer? This is an informed decision each woman should make for themselves in consultation with their doctor, preferably a gynaecologist.

There is no such thing as a 100% risk free contraceptive. Realistically, if you are changing your internal hormonal environment for an extended period of time (between 10 – 30 years), there are bound to be consequences and Dr Apffelstaedt therefore does not recommend the use of a hormone-releasing IUD for more than 5 years. If you wish to extend use for longer than that, it is wise to discuss the risks with your gynaecologist. There are, however, numerous lifestyle changes one can make to decrease the risk of developing breast cancer without changing their birth control and these are unpacked further on in this article.

4. Why should I consider this study if other studies have found no link?
As a surgeon and researcher, Dr Apffelstaedt looks very critically at how studies are conducted.

In his opinion, this study is excellent in comparison to the prior, smaller studies which did not have the level of statistical power necessary to detect the links between hormone releasing IUDs and an increased breast cancer risk.

This was a large-scale study which covered the entire population of the country. It was able to track how many women in the population are on hormone-releasing IUDs based on data extracted from the national Reimbursement Register of the Social Insurance Institution which contains data on purchases of the IUDs since 1994. This could then be isolated to determine the influence in relation to the breast cancer development rate – something they can do with ease as Finland has complete records of breast cancer cases since the 1970s to date.

If one looks at how post-menopausal hormone replacement therapy, which contains pure estrogen, decreases the risk of breast cancer in comparison with how combined hormone replacement therapy increases the risk of breast cancer, it would be surprising if a progestogen-releasing IUD did not increase the breast cancer risk. Whilst there are some shortcomings in the study, Dr Apffelstaedt believes this is a practice-changing study that more will be drawn from in future.

5. What can I do to reduce my risk and stay ahead of breast cancer?
The easiest way to lower one’s risk of developing breast cancer is to live a healthier lifestyle. To reduce your risk:
• Watch your diet and exercise regularly: obesity increases one’s breast cancer risk by up to 70% in pre-menopausal women (American Association for Cancer Research, 2012). This is a far higher than the risk associated with having an IUD for over 10 years! It is of utmost importance to lead a healthy and active lifestyle and do your best to stay within a healthy weight range.

• Reduce your alcohol intake: habitual drinking can also increase your risk. Alcoholics in particular have a far higher risk of developing breast cancer than non-drinkers (National Cancer Institute).

• Screen your breasts on a regular basis: check for lumps by hand if you are under 40 and see your mammographer if you are over 40.
Only once you have considered all of the above, should you start worrying about the risks your IUD may carry.

Concludes Apffelstaedt, “The study may sound scary but speaking to your doctor to explore all your options is the best way forward. Every woman is different and birth control is a highly personal decision. The only reason one should consider studies such as this is in order to ensure one is making an informed decision.”