New evidence on progestagen-only hormonal contraceptives and breast cancer risk

A group of researchers from Oxford University confirmed that progestin-only birth control, which is promoted as a “safer” and “lower-risk” alternative to combined hormonal contraception, is associated with an increased risk of breast cancer.

More than nine thousand premenopausal women with incident invasive breast cancer diagnosed were compared with eighteen thousand healthy controls.  The study aimed to assess the relationship between a woman’s recent use of hormonal contraceptives and her subsequent risk of breast cancer.

The authors of the study reported a relative increase of around 20% to 30% in breast cancer risk associated with the current or recent use of either combined oral or progestagen-only contraceptives.

It is important to note that 44% of women with breast cancer and 39% of women without breast cancer had a prescription for a hormonal contraceptive an average of three years before diagnosis. Half of the hormonal contraceptive prescriptions were for progestagen-only contraceptives.

The researchers found that the increased risk of breast cancer was similar regardless of whether the preparation last used was oral combined, oral progestagen-only, injectable progestagen, progestagen implant, or progestagen intrauterine device.

The researchers examined if the increased breast cancer risk remained elevated for women even after they stopped using birth controlThey compared results from previous studies including women in a wider age range. They found that in young women aged 16-20, the 15-year absolute excess risk of breast cancer associated with the use of oral contraceptives was 8 per 100,000 users. In older women, from age 35 to 39, the risk was 265 per 100,000 users.

The authors concluded that the current or recent use of progestagen-only contraceptives is associated with a slight increase in breast cancer risk, similar to the risk associated with the use of combined hormonal contraceptives. The risk is estimated to be smaller in women who use it at younger age rather than at older ages.

Leave a Reply

You must be logged in to post a comment.