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Newer contraceptive pills may cut ovarian cancer risk in young women

Study suggests long-lasting protection for women

Adrian O'Dowd

Thursday, 27 September 2018

Young women who take new types of combined oral contraceptives (containing both lower doses of oestrogens and newer progestogens) may have a reduced risk of ovarian cancer, suggests a large study* published today by The BMJ.

Researchers from the UK and Denmark said their results showed this positive effect strengthened with longer periods of use and persisted for several years after stopping.

At least 100 million women worldwide use hormonal contraception daily and previous research has shown a reduced risk of ovarian cancer in women who take combined oral contraceptives.

However, most of the evidence relates to the use of older products, containing higher levels of oestrogen and older progestogens.

Experts say that women who use newer oral contraceptives and other hormonal contraceptive methods also want to know whether they are likely to experience the same benefit.

Therefore, researchers at the University of Aberdeen and the University of Copenhagen in Denmark investigated the influence of newer hormonal contraceptives (combined and progestogen-only products) on overall and specific types of ovarian cancer in women of reproductive age.

They used national prescribing and cancer registers to analyse data for 1,879,227 Danish women aged 15-49 years between 1995 and 2014.

Women were categorised as never users (no record of being dispensed hormonal contraception), current or recent users (up to one year after stopping use), or former users (more than one year after stopping use) of different hormonal contraceptives.

Most (86%) of the hormonal contraceptive use related to combined oral products.

After taking into account several factors, including age and parity, the researchers found that the number of cases of ovarian cancer were highest in women who had never used hormonal contraception (7.5 per 100,000 person years), whereas among women who had ever used hormonal contraception, the number of cases of ovarian cancer were 3.2 per 100,000 person years.

There was no firm evidence to suggest any protective effect among women who used progestogen-only products, although the researchers pointed out that few women were exclusive users of these products, which limited the ability to detect an effect.

The reduced risk for combined products was seen with nearly all types of ovarian cancer, and there was little evidence of important differences between products containing different types of progestogens.

Based on these figures, the researchers said that hormonal contraception prevented an estimated 21% of ovarian cancers in this group of women.

This was an observational study, so no firm conclusions could be drawn about cause and effect, but they did support the findings of studies of older products.

The researchers acknowledged that they did not study older women, among whom most cases of ovarian cancer occur, but nevertheless, this was a large study with a long follow-up period.

They said: “Based on our results, contemporary combined hormonal contraceptives are still associated with a reduced risk of ovarian cancer in women of reproductive age, with patterns similar to those seen with older combined oral products.

“The reduced risk seems to persist after stopping use, although the duration of benefit is uncertain. Presently, there is insufficient evidence to suggest similar protection among exclusive users of progestogen-only products.”

*Iversen, L: Fielding, S; Lidegaard, Ø; Mørch, L S; Skovlund, C W; and Hannaford, P C. Association between contemporary hormonal contraception and ovarian cancer in women of reproductive age in Denmark: prospective, nationwide cohort study. BMJ 2018;362:k3609. DOI:10.1136/bmj.k3609

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