Women may face an increased breast cancer risk from taking any kind of hormonal contraceptive, a new study has found.
Scientists say using progestogen-only hormonal contraceptives, including the oral ‘mini pill’, implant, injectable and intra-uterine device, is associated with a 20%-30% higher chance of developing the disease.
Earlier research found that taking the combined contraceptive pill (commonly known as the pill), which includes oestrogen and progestogen, is associated with a small rise in the risk of getting breast cancer that goes down after stopping its use.
But experts point out the benefits of taking the contraceptives, such as protection against endometrial cancer and ovarian cancer, could outweigh the risk of taking them.
The use of progestogen-only contraceptives has gone up a lot in the last few years, but information on their association with breast cancer risk has so far been limited.
There were nearly as many prescriptions issued in England for progestogen-only oral contraceptives in 2020 as there were for the combined pill.
The absolute excess risk of developing breast cancer over a 15-year period in women with five years of using oral contraceptives ranged from eight in 100,000 women for use from age 16 to 20 to 265 in 100,000 for use from age 35 to 39, according to the new findings.
The data, collected by the Clinical Practice Research Datalink (CPRD), was analysed from 9,498 women who developed invasive breast cancer between the ages of 20 and 49, and 18,171 closely-matched women without breast cancer.
Experts said 44% of women with breast cancer and 39% of women without breast cancer who were included in the study had a prescription for a hormonal contraceptive an average of three years before diagnosis.
About half of these women were last prescribed a progestogen-only contraceptive.
Researchers combined the CPRD results on oral contraceptive use with those from other previously published studies to estimate absolute excess risks.
Kirstin Pirie, from Oxford Population Health, and one of the lead authors, said: “Given that a person’s underlying risk of developing breast cancer increases with advancing age, the absolute excess risk of breast cancer associated with either type of oral contraceptive will be smaller in women who use it at younger ages.
“These excess risks must, however, be viewed in the context of the well-established benefits of contraceptive use in women’s reproductive years.”
Gillian Reeves, professor of statistical epidemiology and director of the cancer epidemiology unit at Oxford University, said: “I don’t really see that there’s any indication here to say that women need to necessarily change what they’re doing.”
She said the combined oral contraceptives and the progestogen-only contraceptives are “just the same in terms of breast cancer risk, they seem to have a very similar effect to the other contraceptives”.
“I suspect that if women were prepared to accept those risks in the past, in return for the many benefits of taking hormonal contraceptives, then they may well be prepared to carry on doing that.”
‘Breast cancer rare in young women’
Dr Kotryna Temcinaite, from the charity Breast Cancer Now, said: “For both types of contraceptives, if you stop using them, this added risk of breast cancer reduces over time.
“Breast cancer is rare in young women. A slight increase in risk during the time a woman uses hormonal contraceptive means only a small number of extra cases of the disease are diagnosed.”