All hormonal contraceptives carry a slightly higher risk of breast cancer, including progestogen-only pills, a study has found.
The researchers who carried out the study stressed that the increased risk of breast cancer needs to be weighed against the benefits of hormonal contraceptives, including protection they provide against other forms of female cancer, reported the Science Alert.
Previous studies have established an increased risk of breast cancer with combined contraceptives, which use both estrogen and progestogen.
Although the use of progestogen-only contraceptives has been increasing for over a decade, little research has been done on their links to breast cancer.
The study, published in PLOS Medicineconcluded that a woman’s risk of developing breast cancer was about the same for combined hormonal contraceptives as for those using progestogen only.
According to the study, women who take hormonal contraceptives have a 20 to 30% higher risk of developing breast cancer than those who do not use them. The results are similar to those previously published, including a wide range of study from 1996.
The risk also remains virtually the same regardless of the method of administration – oral pill, IUD, implant or injection.
Taking into account that the probability of breast cancer increases with age, the authors calculated the risk associated with hormonal contraceptives. For women taking hormonal contraceptives over a five-year period between ages 16 and 20, that represented eight cases of breast cancer per 100,000, they said. Between 35 and 39 years old, there were 265 cases per 100,000.
“Nobody wants to hear that something they’re taking is going to increase their risk of breast cancer by 25%,” said Gillian Reeves, professor of statistical epidemiology at the University of Oxford and one of the study’s authors. “What we’re talking about here is a very small increase in absolute risk,” she said.
“These increases in breast cancer risk must, of course, be seen in the context of what we know about the many benefits of taking contraceptives hormones,” he added.
“Not just in terms of birth control, but also because we know that oral contraceptives actually provide quite substantial and long-term protection against other female cancers such as ovarian cancer and endometrial cancer,” he continued.
The study also confirmed, like others, that the risk of breast cancer decreases in the years after a woman stops using hormonal contraceptives.
Stephen Duffy, a professor at Queen Mary University in London who was not involved in the study, saidwrote the conclusions as “reassuring insofar as the effect is modest”.
The study involved data from nearly 10,000 women under 50 who developed breast cancer between 1996 and 2017 in the UK, where use of progestogen-only contraceptives is as widespread as the combined method.
Gillian Reeves has indicated that there are several explanations for the increasing use of progestogen-only contraceptives. They are recommended for women who are breastfeeding, who may be at risk of cardiovascular problems or smokers over 35.
ZAP // 
