New types of combined oral contraceptives that contain both lower doses of oestrogens and newer progestogens are linked to a reduced risk of ovarian cancer in young women, a study has found.
According to researchers, their results show that this positive effect was strengthened with longer periods of use and persisted for several years after stopping, providing reassurance for women.
“Contemporary combined hormonal contraceptives are still associated with a reduced risk”
Previous studies have also shown a reduced risk of ovarian cancer in women who take combined oral contraceptives.
However, most of the evidence related to the use of older products, containing higher levels of oestrogen and older progestogens, noted the researchers in the British Medical Journal.
They highlighted that women who used newer oral contraceptives and other hormonal contraceptive methods also wanted to know if they were likely to experience the same benefit.
The researchers, from Aberdeen University and Copenhagen University, looked at the effect of combined and progestogen-only products on overall and specific types of ovarian cancer in women.
Using national prescribing and cancer registers, they analysed data for nearly 1.9 million Danish women of reproductive age between 15 and 49 years.
Women were categorised as never users of different hormonal contraceptives, current or recent users or former users.
The researchers found that the number of cases of ovarian cancer were highest in women who had never used hormonal contraception at 7.5 per 100,000 person years.
“The reduced risk seems to persist after stopping use, although the duration of benefit is uncertain”
In contrast, 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, said the researchers who were led by Dr Lisa Iversen.
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 progestogens.
Similar results were also found among women followed up to their first switch in contraceptive type.
Based on these figures, the researchers concluded that hormonal contraception prevented an estimated 21% of ovarian cancers in this group of women.
The researchers highlighted that they did not study older women, among whom most cases of ovarian cancer occur.
However, it was a large study with a long follow-up period, and the researchers noted that they were able to adjust for a range of potentially influential factors.
“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,” said the study authors.
“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,” they said.