Ask An Expert: Do Hormonal Contraceptives Increase Cancer Risk?

Health 2023

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Ask An Expert: Do Hormonal Contraceptives Increase Cancer Risk?
Ask An Expert: Do Hormonal Contraceptives Increase Cancer Risk?

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Video: Do birth control pills increase the risk of breast cancer? 2023, January


ANSWERS TO MOST OF THE QUESTIONS ARE EXCITING TO US we used to search online. In the new series of materials, we ask just such questions: burning, unexpected or common - to professionals in various fields.


We recently asked an expert about whether the use of hormonal contraception actually threatens depression or decreased libido. As it turned out, the data are contradictory, and most importantly, what they indicate is the need for further research. Another common reason for doubt when it comes to hormonal contraception is the fear that they may increase the risk of breast cancer, ovarian cancer, or other malignant tumors. We figure out if this is so.

Oksana Bogdashevskaya

doctor - obstetrician-gynecologist, chief gynecologist of the Fomina Clinic network, author of the blog "The most thankless work"


Today it is clearly known that COCs do not increase the risk of cancer in general and even reduce it. This was illustrated in the Royal College of General Practitioners (RCGP) cohort study of nearly 50,000 women followed for 44 years. It found that the use of COCs is associated with a reduced risk of colorectal cancer, endometrial cancer and ovarian cancer. The risk of breast and cervical canal cancer increased in patients using COCs at the present time or recently completed their use, but this risk completely regressed within five years. In addition, this is offset by a decrease in the risk of endometrial, ovarian and colon cancer, which persists for at least thirty years.

Data from a large observational RCGP cohort study of more than 1 million women-years (the number obtained by multiplying the number of participants by the number of years of follow-up. - Approx. ed.), indicate a decrease in the risk of any malignant tumors in users of oral contraceptives by 12%, and the risk of gynecological malignant tumors by almost a third - by 29%.

If you look at the data for different diagnoses, then, perhaps, they are the most controversial for breast cancer. For example, an analysis of data from 150,000 women who participated in 54 epidemiological studies showed that overall, those who ever used oral contraceptives had a small (7%) increase in the relative risk of breast cancer compared with women who never used oral contraceptives. not used. According to the same analysis, right while taking oral contraceptives, the risk increases by 24%, but does not depend on the duration of use, and after cancellation it gradually decreases and over ten years becomes the same as in the general population.

In 2010, a study was completed, in which more than 116 thousand women took part in twenty years. There was a slight increase in the risk of breast cancer (5.6%) in COC users (and not all). There are studies that do not show the risk, there are those that show the risk, but only during the period of admission. There is, for example, a study where an increased risk of breast cancer was noted, but the drugs were high-dose and are now outdated. Most of the results suggest that past use of COCs does not increase risk. The experts conclude that a small increase in breast cancer risk is balanced by a significant decrease in the risk of ovarian and endometrial cancer.

Data from a large observational RCGP cohort study show a 12% reduction in the risk of any cancer in oral contraceptive users

In three large prospective cohort studies, including the Nursing Health Study, the RCGP Study, and the Oxford Family Planning Association study, neither past long-term use of COCs nor current use were associated with an increased risk of breast cancer.In a study comparing 4574 women with breast cancer and 4682 control participants, the risk of developing breast cancer was similar among those who took and did not take COCs.

In 2017, the authors of a large study from Denmark reported a high risk of breast cancer associated with modern oral contraceptives. In comparison with those who had never taken COCs, the risk was increased by almost 20%, and the range of data ranged from 0 to 60%. But Danish research on COCs as a whole raises many questions in the scientific and medical community.

Nevertheless, even if the results are reliable, the absolute increase in breast cancer in COC users was small: 13 per 100,000 person-years (approximately one additional case per 7,690 women per year). For women under the age of 35 (the age group most frequently using COCs), the risk was only 2 cases per 100 thousand person-years (1 additional case per 50 thousand women per year).

The risk of cervical cancer increases with the use of COCs; however, it is still unclear whether there is a causal relationship, because the main cause of this disease is the human papillomavirus. Today it is known that for five years of taking COCs, the risk increases by 10%, and when taken for more than ten years, it doubles, and this is especially true for women with HPV infection. The most compelling evidence from the Collaborative Cervical Cancer Epidemiological Study Group is that the authors reanalyzed and pooled data from 24 epidemiological studies involving 16,573 women. The risk of invasive cervical cancer increased with increasing duration of COC use. True, the absolute increase in risk was low: ten years of use between the ages of 20 and 30 could increase the cumulative incidence by about 1 in 1000 women. The risk decreases after the withdrawal of COCs and within ten years becomes the same as in women who do not use them.

The risk of cervical cancer increases with the use of COCs; however, it is still unclear if there is a causal relationship

Women who have ever used COCs have a lower risk of developing endometrial cancer than those who have never used oral contraceptives. The risk is reduced by at least 30%, and the longer COC use, the lower the risk. It decreased especially strongly in those who smoked, in women with obesity or a sedentary lifestyle. The protective effect persists for many years after the discontinuation of COC use.

Progestin-only contraceptives (such as injections, implants, and intrauterine hormonal systems) also protect the endometrium. In Finland, more than 98 thousand women are registered in the national register using intrauterine hormonal systems (20 μg levonorgestrel daily; Mirena); among them, a decrease in the incidence of endometrial cancer was found. In last year's Norwegian study, Women and Cancer, the risk of endometrial cancer in women using such contraceptives was also reduced.

Women who have ever used COCs have a 30-50% lower risk of developing ovarian cancer than those who have never used them, and the longer a woman uses this method of contraception, the greater the protection. The protective effect lasts up to thirty years after the use of COCs is discontinued.

As for the predisposition to breast or ovarian cancer, today WHO does not believe that the presence of BRCA 1 or 2 mutations prevents or limits the use of COCs. According to a 2013 study, the risk of breast cancer in those taking hormonal contraceptives did not increase with these mutations. Since COCs also reduce the risk of ovarian cancer in women with BRCA1 or BRCA2 gene mutations, the possibility of using them to prevent cancer in women with these mutations is being discussed.

As for other oncological diseases, COCs reduce the risk of developing colorectal cancer by 15–20% and reduce the risk of cancer of the fallopian tubes. There were concerns about the connection between the use of COCs with an increased risk of melanoma, but they have been refuted.

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