Chemotherapy can cause infertility in women who haven’t been through the menopause. It can affect the functioning of the ovaries, reducing the number or quality of eggs.
The likelihood of becoming infertile depends on the type of chemotherapy drugs used, the dose given and your age.
The chemotherapy drugs most likely to cause infertility are a group called alkylating agents. One of these (cyclophosphamide) is commonly used in combination with other chemotherapy drugs to treat breast cancer.
The effect of some other chemotherapy drugs, such as taxanes (docetaxel and paclitaxel), on fertility hasn’t been as widely studied, but evidence suggests they’ll also have a negative effect on fertility.
Chemotherapy can also cause your periods to stop. This may be temporary or permanent. In general the younger you are when having treatment, and particularly if you’re under 35, the more likely it is that your periods will return.
Even if your periods return after chemotherapy, it doesn’t necessarily mean your fertility has been unaffected. The menopause is likely to happen five to ten years sooner than it would have done if you hadn’t had chemotherapy.
It is important to speak to your oncologist if you have any concerns.
Tamoxifen is a hormone treatment used in women whose breast cancer is oestrogen receptor positive.
In most pre-menopausal women who take tamoxifen, the ovaries continue to work. When you start taking tamoxifen it may stimulate ovulation and make you more fertile. With continued use, in some women (about half) periods become less regular, lighter or disappear altogether.
Generally your periods will start again once you stop taking tamoxifen, as long as you haven’t gone through the menopause naturally while taking the drug. However, it may take four to five months for your cycle to become regular again.
You’ll be advised not to get pregnant while taking tamoxifen because it may harm a developing baby.
Because of the length of time it’s taken for, the side-effects of tamoxifen may make it difficult to tell if you’ve started the natural menopause while taking it. It may only be when you finish taking it that you realise your menopause has started.
Ovarian suppression or ablation
This involves stopping the ovaries from working, either temporarily or permanently, or removing the ovaries.
Goserelin (Zoladex) is a hormone treatment that “switches off” the production of oestrogen from the ovaries. Your periods should usually start again within three to six months of stopping goserelin treatment, unless your natural menopause has occurred during your treatment.
Ovarian ablation many involve an operation to remove the ovaries. This will result in an immediate menopause and permanent infertility.
Radiotherapy is an alternative way of stopping the ovaries from working. It destroys the eggs so the ovaries become inactive. This brings on an early menopause resulting in permanent infertility. Using radiotherapy for ovarian ablation is not common in the UK.
Women are generally advised not to get pregnant while having treatment for breast cancer. This is because treatment for breast cancer can damage an unborn baby at the early stages of development.
Women having treatment for breast cancer (including the hormone treatment tamoxifen) are recommended to use non-hormonal methods of contraception, such as condoms, Femidoms or a diaphragm.
It may also be possible to use a coil (IUD or intrauterine device). However, discuss this with your specialist because not all types are suitable for women with breast cancer.
The contraceptive pill is less commonly advised after a diagnosis of breast cancer. This is because the hormones in the contraceptive pill could possibly stimulate any remaining breast cancer cells. The morning-after pill can be used in emergencies – it’s a single dose of hormones and unlikely to affect your breast cancer.
You should use reliable contraception before and throughout treatment. After treatment your decisions about contraception will depend on how you feel about getting pregnant.
Generally, you should assume you could still get pregnant unless you haven’t had a period for at least a year after completing your treatment if you’re 40 or over, or two years if you’re under 40. However, this is a general guide and varies for each person.
Male Fertility Issues
Men about to undergo cancer treatment may wish to preserve a sperm sample. We can refer you to the Andrology Department at Hammersmith Hospital for sperm storage.
Sperm Banking Instruction Leaflet can be viewed here
Fertility and cancer treatment advice for men
Cryopreservation of Sperm after referral by a Medical Practitioner Information Leaflet
Clinicians Referral Letter
Hammersmith Hospital Andrology Laboratory – click here for a map.