What’s the lowdown?
- Most people who choose to use contraception do not expose themselves to long-term cancer harms and instead may benefit from a lowering of their risk of some cancers which persists for many years after stopping use
- Combined contraception can increase your chances of developing breast and cervical cancer, but these risks are small
- There is less research into progestogen-only contraception and breast or cervical cancer, but there may be a slightly increased risk
- Keeping up to date with cervical screening, getting the HPV vaccination if you’re eligible, and using condoms can help protect yourself against cervical cancer
- Hormonal contraception has a protective effect against endometrial (womb), ovarian and bowel cancer
- The copper coil could also have a protective effect against endometrial and cervical cancer.
It’s something nobody likes to think about, but cancer can’t be ignored, and it’s important that we’re clued up about our individual risks. Lots of people believe that particular types of contraception increase your risk of cancer, but that might not be entirely true. In fact, some contraceptives might actually protect you against certain types of cancer.
Let’s dive into different types of contraception and what impact these can have on your risk of developing some types of cancer.
Combined hormonal contraception
Combined contraceptive methods contain both oestrogen and progestogen. The most common combined contraceptive method is the combined pill. Microgynon, Cilest and Yasmin are all popular brands of the combined contraceptive pill. The patch and the vaginal ring are also combined birth control methods.
The combined pill slightly increases your risk of developing breast cancer. This risk is very small; in the 30-39 age group, 14 more women in every 10,000 will develop breast cancer if they take the combined contraceptive pill. In younger age groups, the numbers are even smaller.
To put this into perspective, your risk of being a victim of credit card fraud is 2000 in every 10,000. That’s 143 times greater.
Research suggests that the longer you take the combined pill, and the more recently you have been on it, the higher your risk of developing breast cancer. This slightly elevated risk reduces once you stop taking the pill, and ten years after stopping, your risk will be back to normal.
One study also found that the amounts and types of oestrogen and progestogen in your combined contraception can affect your risk of developing breast cancer, but there isn’t enough research to expand on this just yet.
It’s important to point out that your risk of developing breast cancer is also dependent on factors other than your contraception. Whether or not you smoke, your weight and your genes all play a role.
Everyone has BRCA genes, which protect us against breast and ovarian cancers. Some people have a faulty BRCA1 or BRCA2 gene, meaning this protective effect doesn’t work as it should. If you have a family history of breast cancer, or know that you have a faulty BRCA gene, you should speak to your doctor before beginning combined contraception. This is because you might already be at a higher risk of developing breast cancer.
Every time we ovulate, our ovaries are slightly damaged. Damage to the ovaries, over time, can cause ovarian cancer in some cases. When we take hormonal contraception, which stops ovulation and prevents this damage from occurring, this can reduce the risk of developing ovarian cancer.
A huge study in Denmark which looked at nearly two million women over a nineteen year period found that any combined hormonal contraception – like the pill, ring and patch – provided a significant protective effect against ovarian cancer. This effect was more pronounced the longer a woman had been taking her contraception, and reduced once she stopped.
Other studies have found a benefit of decreased risk of ovarian cancer for many years after stopping hormonal contraception, and that this gradually reduces over time.
Endometrial cancer is cancer of the lining of the womb. Users of the combined pill have been found to have half the risk of developing endometrial cancer than those who have never used hormonal contraception, and this protective effect is the highest if you are currently taking combined contraception. People who recently stopped taking combined contraception still have a reduced risk, and this will slowly decrease the longer it is since stopping.
The protective effect against endometrial cancer has also been found across all combined contraception types, and it is thought that this protection could last up to twenty years after stopping contraception in some cases.
The Oral Contraception Study followed 46,000 women to monitor the long term impact of taking the combined contraceptive pill. The study found that taking the pill for any length of time lowered the cases of bowel cancer.
Unlike combined contraceptive methods, progestogen-only contraception contains no oestrogen – just progestogen. The mini pill is a form of progestogen-only contraception, and brands like Micronor, Noriday and Cerazette are popular in the UK. The implant and the injection and the hormonal coil (IUS) are also forms of progestogen-only contraception.
Most research into this area involving progestogen-only contraception looks at all hormonal methods, grouping progestogen-only and combined contraception together. This makes it really tricky to definitively say whether or not progestogen-only methods affect breast cancer risk.
The NHS website states that if there is an increased risk of breast cancer from the mini pill, it is likely to disappear when you stop taking it.
There is some evidence that the hormonal coil can very slightly increase your risk of developing breast cancer.
Unlike combined methods however, progestogen only methods are generally considered safe for people with a BRCA gene mutation to use. Someone with current breast cancer, and most people with a history of breast cancer, should not use any form of hormonal contraception.
The Danish study didn’t find any protective effects of progestogen-only contraception, but there are others that have. Using the hormonal IUS has been associated with reduced cases of ovarian cancer, as has the injection, both of which are progestogen-only.
It is possible that inconsistencies in the research for progestogen-only contraception are because of the way certain progestogen-only contraceptives work. While most hormonal contraception works to suppress ovulation on some level, some progestogen-only contraceptives do so more than others. It could be that those that suppress ovulation less (like the hormonal IUS, which tends to prevent pregnancy by thinning the lining of the womb and thickening the cervical fluid at the neck of the womb) see less consistent protective effects in the research.
Research into the effects of progestogen-only contraceptive methods on endometrial cancer risk is less common, but does suggest that it provides similar protection against the disease.
This research looked at all oral contraceptives and found a significant protective effect against endometrial cancer.
The Mirena coil, a brand of hormonal coil (IUS), is also licensed for use to protect the womb lining from the effects of oestrogen used in hormonal replacement therapy for menopausal symptoms. This is because if oestrogen is used to treat menopausal symptoms without progestogen, this will cause the womb lining to grow, risking cancerous changes.
People who have infrequent periods (less than every three months) because of PCOS can use contraceptive options such as the combined pill or hormonal coil (IUS) to keep the lining of the womb thin and reduce their risk of cancerous changes.
Research which looked at all oral contraceptives and found a significant protective effect against endometrial cancer.
Hormonal contraception and cervical cancer
There is reliable evidence that long-term use of both the combined and mini pill can increase your risk of cervical cancer up to four times. The same study found that women who had been taking the pill for 5-9 years were nearly three times more likely to develop cervical cancer than women who had never taken the pill.
However, this increase is only seen in those who have human papillomavirus (HPV). HPV is common, and usually goes away on its own and doesn’t cause any problems – most people won’t even know they have had it.
This might sound alarming, but there is also evidence that this risk diminishes once you stop taking hormonal contraception, and to put it into perspective, just 0.7% of UK women develop cervical cancer during their lifetime. This number includes those who are taking hormonal contraception and those who are not.
Other hormonal contraception
Reviews of the evidence suggest that there is a strong link between hormonal contraception in general and increased risk of cervical cancer. This risk increases the longer you are taking your contraception, with people who have been using hormonal contraception for five years or more having the greatest risk.
It’s difficult to say whether particular types of hormonal contraception, like the mini pill, vaginal ring, injection, patch and implant, have a lesser or greater effect on your risk of developing cervical cancer. More research is needed in this area.
It’s also important to remember that your risk of developing cervical cancer, whether you use the pill or not, is extremely low if you do not have HPV. Keeping up to date with your cervical screening, getting vaccinated against HPV if you are eligible, and using condoms are great ways to protect yourself from HPV and from any greater risk of cervical cancer that it may cause.
Mary Hargreaves is a writer and author with a passion for women’s reproductive health. She has a Masters in Clinical and Health Psychology, and has worked in scientific research across a range of disciplines.