According to the study, progestin-only and progestin with estrogen contraceptives are associated with a slight increase in breast cancer risk.
The study published in the open-access journal PLOS Medicine noted that the risk of breast cancer was similar regardless of whether birth control was progestin and estrogen combined or progestin only.
The World Health Organisation, however, said approximately half of breast cancer developed in women with no identifiable risk factor other than being a female and over 40 years of age.
The global health organisation further explained that certain factors increase the risk of breast cancer.
The WHO listed the factors as increasing age, obesity, harmful use of alcohol, family history of breast cancer, history of radiation exposure, reproductive history, tobacco use, and postmenopausal hormone therapy.
However, the new study found that those prescribed oral combined contraceptives, injectable progestagens, and progestagen-releasing IUD contraceptives were at increased risk of breast cancer.
Scientists from the United Kingdom used the Clinical Practical Research Datalink for their study. They evaluated the medical records of 9,498 women under 50 with invasive breast cancer. All the women received their diagnosis between 1996 and 2017.
The researchers also looked at 18,171 medical records to use as a control group.
During the study, the researchers discovered that 44 per cent of women with breast cancer had hormonal birth control prescriptions, with about one-half for progestin-only.
They also found out that 39 per cent of the women in the control group had a prescription for hormonal birth control, while about one-half were for progestin-only.
Speaking on their findings, a medical oncologist and director of Breast Medical Oncology for the Margie Petersen Breast Center at Providence Saint John’s Health Center, Dr. Parvin Peddi told Healthline that women do not need to choose a progestin-only containing birth control medication because of the perceived lower risk of birth cancer.
She added, “We have known that oral contraceptives slightly increase the risk of breast cancer.
“This study aims to determine if progestin-only containing oral contraceptives has a lower risk or whether the delivery mode, for example, oral vs. injectable vs. intrauterine device, affects risk. The study found a similar increased risk of breast cancer among all the above options.
“The main take-home message is that this study finds that women do not need to choose a progestin-only containing birth control medication because of the perceived lower risk of birth cancer.”
“On the other hand, it’s important to note that the absolute increased risk of breast cancer from any of these medications is quite low, and this study should not dissuade women from using hormone-containing birth controls,” Peddi said. “The risk of breast cancer was seen in less than 0.5% of women aged 35-39 due to these medications and in even fewer women who used these medications at a younger age.”
An oncologist at Federal Medical Centre, Abeokuta, Dr. Tola Kusimo argued that while the study provided evidence regarding the short-term associations between hormonal contraceptives and breast cancer risk, it did not do so for longer-term associations or the effect of the total duration of contraceptive use.
Kusimo added, “I have also seen the study that you are talking about. But you need to understand that breast cancer risk can go up with both combined and progestogen-only hormonal contraception, however, the risk is minimal.
“The risk is lower in younger women, unlike when the person using the contraceptive is an older woman.
“The best ways to reduce cancer risk are to quit smoking, eat a healthy, balanced diet, drink less alcohol, and maintain a healthy weight. Contraception has a wide range of potential advantages as well as hazards that are unrelated to cancer.”
