A new study has provided an updated estimate of the cancer risks linked to hormonal contraception.
Dr Kirstin Pirie and colleagues at Oxford University, UK, focused on the use of progestogen-only contraceptives, which has increased substantially in recent years.
They analysed figures from the Clinical Practice Research Datalink on 9,498 women who developed breast cancer between ages 20 to 49, and 18,171 similar women without breast cancer.
Among those who developed breast cancer, 44% were taking a hormonal contraceptive an average of three years before diagnosis. Among those who did not develop breast cancer, 39% were taking a hormonal contraceptive.
In both groups, about half of the hormonal contraceptives used were progestogen-only.
Findings appeared yesterday in PLoS Medicine. After taking into account a range of risk factors including body mass index, the breast cancer risk was estimated alongside results from other previously published studies.
This showed there was a rise in risk linked to both types of hormonal contraceptive of around 23%.
Progestogen only oral contraception including tablets, injections and the intrauterine device were linked to around a 25% raised risk.
In previous studies, any rise in the cancer risk was seen to fall again after stopping use.
“The findings suggest that current or recent use of all types of progestogen-only contraceptives is associated with a slight increase in breast cancer risk, similar to that associated with use of combined oral contraceptives,” said Dr Pirie.
“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.”
Pirie, K. et al. PLoS Medicine 21 March 2023
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