Study: Progestogen-only contraceptives slightly increase breast cancer risk

Article

In a recent study, the risk of developing breast cancer was greater in women with current or recent use of progestogen-only contraceptives.

Current or recent use of progestogen-only contraceptives leads to a slight increased risk of developing breast cancer, according to a recent study.

Investigators conducted a study to analyze the risk of breast cancer in premenopausal women because of current or recent use of progestogen-only contraceptives. Data was gathered from the Clinical Practice Research Datalink (CPRD), containing medical records for over 11 million individuals in the United Kingdom.

A nested case control design was used to examine the association between hormonal contraceptives and intrusive breast cancer. Participants included women aged 20 to 49 years with incidence of intrusive breast cancer recorded from January 1, 1996, to September 20, 2017. CPRD Read codes were used to define invasive breast cancer.

Each case was matched with 2 controls based on index date, year of birth, general practice, and observation period. A minimum of 12 months of follow-up before the index date was required for cases and controls.

Women with 1 or more prescriptions for a hormonal contraceptive during the observation period were defined as having a prescription, while those without a prescription were defined as nonusers. Women with a prescription less than 12 months before the index date were defined as current users of oral contraceptives.

Classifications of prescriptions included oral combined contraceptive, oral progestogen-only contraceptive, injectable progestogen, progestogen implant, and progestogen-releasing intrauterine device (IUD).

There were 9498 breast cancer cases analyzed, with 18,171 matched controls. Two percent of cases and controls were aged under 30 years, 21% aged 30 to 39 years, and 77% aged 40 to 49 years.

One or more prescriptions for an oral contraceptive were seen in 44% of cases and 39% of controls. Of these, 67% had only 1 type of hormonal contraceptive prescribed during the observation window.

Women with at least 1 hormonal contraceptive prescription were at greater risk of developing breast cancer. The time between last hormonal prescription and breast cancer development averaged at 3.1 years. 

Odds ratios (ORs) for breast cancer were 1.23 for oral combined, 1.26 for oral progestogen-only, 1.25 for injectable progestogen, 1.22 for progestogen implant, and 1.32 for progestogen IUD. This indicated significantly raised ORs for each of these hormonal contraceptive prescriptions.

Reference

Fitzpatrick D, Pirie K, Reeves G, Green J, Beral V.Combined and progestagen-only hormonal contraceptives and breast cancer risk: A UK nested case–control study and meta-analysis. Plos Medicine. 2023. doi:10.1371/journal.pmed.1004188

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