Monday, March 27, 2023
A recent study (1) has found there to be an increased link between breast cancer and the Progesterone only Pill (POP) or Mini Pill. Past studies had looked at the association between the Combined Oral Contraceptive Pill (COCP) and breast cancer, but this is the first of its kind to examine the POP. Any link between the POP and breast cancer previously surmised was by extrapolation from studies of the COCP. With POP usage increasing in recent years, it was time to clarify the risks with a study devoted to just that.
The study looked at almost 10,000 women diagnosed with breast cancer over a 7-year period and compared them with just over 18,000 ‘matched controls.’ Essentially these were women who did not have breast cancer and were matched for variables such as age, GP practice, body mass index, number of recorded births, time since last birth, and alcohol intake. Their contraceptive history was then examined.
Overall, 44% of the cases and 39% of control women had a prescription for a hormonal contraceptive an average of 3 years before diagnosis, around half of whom had last been prescribed a progestogen-only contraceptive. The risks were similarly raised if the last hormonal contraceptive prescription was for a COCP, POP, injected progesterone, or progesterone-releasing intrauterine devices (IUD such as the Mirena coil.)
The findings suggest that there is a relative increase of around 20% to 30% in breast cancer risk associated with the current or recent use of either combined oral or progesterone-only contraceptives. The risk is similar for both contraceptives.
Obviously, the risks need to be considered when taking any medication. However, to understand the risks properly it helps to understand the relative risk and absolute risks. The relative risk of taking hormonal contraception is an increased breast cancer risk of 20-30%, however, this is in addition to the background risk.
Every woman has a background risk of breast cancer which is based on a number of risk factors such as age, BMI, alcohol intake, family history, age at which periods start, age of menopause, and activity levels. Someone with a normal BMI, with no significant family history who doesn’t drink alcohol and who exercises more than 2.5 hours per week for example would have a low background risk of breast cancer, and a 20-30% risk increase would not increase their absolute risk by a lot.
The team that performed this study also combined their results with those of 12 previous observational studies which took into account a larger age range of women to calculate the absolute risk. The results showed that hormonal contraception would result in an extra 8 breast cancer cases per 100,000 users between the ages of 16-20 years and an extra 265 breast cancer risk between the ages of 35-39. This amounts to an increase in breast cancer risk for the 15 years after stopping hormonal contraception from 0.5 % to 0.57% in women who use it between the ages of 25-29. In women who take it between the ages of 35-39, the risk rises from 2.0 to 2.2 %.
So, as you can see the absolute risk is actually quite small.
It’s also important to remember that the increased risk does decline over time. An increased relative risk of 33 % drops to around 15% after 5 years of stopping oral contraception.
Yes, there are lots including:
If you need further advice, speak to one of our pharmacists today.