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Combined estrogen-progestogen for contraception and menopausal therapy: is there a cancer risk?
Context - Combined estrogen-progestogen pills are used both as oral contraceptives and for hormone therapy in menopausal women.
Their use has been linked to an increase in some cancers, and a decrease of others. This report present the conclusions reached by the International Agency for Research on Cancer (IARC) – associated to the WHO - on the topic.
No more recent international assessment on the subject was identified since the IARC monograph publication.
A summary of this monograph is available in Lancet Oncology
What are the conclusion of this report?
The conclusion made in this report is that combined estrogen–progestogen
contraceptives can increase the risk for cervical
cancer in women who have a human
The authors recommend thus that women who suffer from papillomavirus
infection and use this form of
hormonal contraception over a long
period of time participate in cervical
cancer screening programmes.
What is the evidence that contraceptive combining estrogen and progestogen hormones are carcinogenic?
, according to the IARC report, to conclude for the
carcinogenicity in humans of combined
oral estrogen–progestogen contraceptives (Group 1 classification of IARC). This
evaluation was made on the basis of increased risks:
On the contrary the report concludes that there is evidence in humans
suggesting a lack of
carcinogenicity of combined
oestrogen-progestagens for colorectum and even convincing evidence for their
protective effect against carcinogenicity indn the endometrium (the
lining of the uterus) and the ovary.
- For breast
cancer, the evidence suggests
an increase in the relative risk among current and
recent users, and that 10 years after cessation of use the risk goes back to
- For cervical cancer, the totality of the evidence
indicated that, overall, the risk increased with increasing
duration of use of combined hormonal
- For uterine
(endometrial), the risk is
approximately reduced by half in women who had taken these
medications. The risk reduction was generally greater with a longer duration
of use and persisted for at least 15 years after cessation of use, although
the extent of the protective effect may wane over time.
- For colorectal
cancer, most studies did not show an increase in
risk in women who had ever used contraceptives or in relation to
duration of use.
Is the use of combined estrogen−progestogen hormones for menopausal therapy beneficial or presenting a risk?
The beneficial effects of combined
hormonal menopausal therapy have been
established unambiguously. However, there is a possibility that women who use
both combined estrogen– progestogen contraceptives and menopausal therapy during
their lifetime may experience effects that are greater than those experienced by
women who use either contraceptives or menopausal therapy but not both.
There is in particular unambiguous evidence for an increase in breast
density, breast tenderness and vaginal bleeding. For breast and uterine, the
combined estrogen– progestogen menopausal
treatment increases the
- For breast
cancer the increased
risk is largely confined to current or recent users with increasing
duration of use of the combined
- For uterine cancer, an increased risk is
observed only if progestogens are taken for less than 10 days per month and
not observed when progestogens are taken daily. The risk is thus decreasing
inversely to the number of days per month of
, there is evidence suggesting lack of
carcinogenicity in humans
associated to a combined estrogen– progestogen therapy.