Key points
- Chemotherapy (especially alkylating drugs), radiotherapy to the pelvis or brain, surgery on the reproductive organs and stem cell transplant can reduce fertility temporarily or permanently [1, 2].
- The ASCO guideline recommends that all patients be counselled about fertility risks at diagnosis and that fertility preservation be raised before treatment starts [5].
- The main methods: sperm freezing in men; freezing embryos, eggs or ovarian tissue, and moving the ovaries before radiotherapy in women [5].
- Survivors who had seen a fertility specialist had less regret, whatever they decided [1].
- Reduced fertility does not mean pregnancy is impossible; use contraception during treatment and ask about using condoms [1, 3, 4].
- Sexual problems can be treated: vaginal lubricants and moisturisers, medicines to improve erections and sex counselling are common options [10].
How does cancer treatment affect fertility?
The effect of treatment on fertility depends on the type, dose and length of treatment, the patient's age, the time since treatment, the type and site of the tumour and fertility before the illness [1, 2].
- Chemotherapy: some drugs, especially alkylating agents, carry a high risk; in women the ovaries may stop producing eggs and oestrogen (premature ovarian insufficiency), and in men the sperm-making cells may be damaged. High doses or combinations of several drugs increase the risk [1, 2].
- Radiotherapy: radiation to the pelvis can damage the ovaries or testicles; radiation near the womb can change its blood supply, and radiation to the brain may affect the glands that control fertility hormones [1, 2].
- Surgery: removal of the womb or both ovaries, or pelvic operations such as on the prostate, bladder and rectum, can affect fertility or ejaculation [1, 2].
- Hormone therapy: can cause ovarian insufficiency in women and lower the sperm count in men [1, 2].
- Targeted therapy and immunotherapy: their effect on fertility is still being studied; some tyrosine kinase inhibitors may reduce fertility [1, 2].
Premature ovarian insufficiency can bring hot flushes, night sweats, irregular or absent periods, vaginal dryness and lower sex drive, and in the long term it raises the risk of osteoporosis and heart disease [1].
Fertility preservation: before treatment starts
Suggested steps at diagnosis
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2. Referral to a fertility specialist
If you would like to have children in the future or are not yet sure, ask for an early referral to a fertility specialist (oncofertility or reproductive endocrinology) [5].
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3. Choosing the right method
Your care team and the fertility specialist look together at the timing of fertility preservation and the possible effect of any delay in starting treatment [2].
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4. Follow-up after treatment
If there was no chance to preserve fertility before treatment, or not enough eggs or embryos were stored, fertility preservation methods may also be offered after treatment [5].
| Method | For whom | Explanation |
|---|---|---|
| Sperm freezing | Men after puberty | The commonest method; it must be done before treatment. If a semen sample is not possible, extracting sperm from the testicle (TESE) is an option [2, 5]. |
| Embryo freezing | Women after puberty | Stimulating the ovaries with medicines, collecting eggs, fertilising them in the laboratory and freezing the embryos [1, 5]. |
| Egg freezing | Women after puberty | Collecting and freezing mature eggs for fertilisation in the future [1, 5]. |
| Ovarian tissue freezing | Women and girls, including the only established method before puberty | Surgically removing ovarian tissue and transplanting it back in the future [1, 5]. |
| Moving the ovaries | Women having pelvic radiotherapy | Moving the ovaries surgically out of the radiation field [1, 5]. |
| Testicular shield | Men having pelvic radiotherapy | A cover to reduce scattered radiation to the testicles [2]. |
| GnRH agonist with chemotherapy | Women with breast cancer | Not a replacement for established methods, but it can be offered as an extra method [5, 7]. |
Freezing testicular tissue in boys before puberty is still experimental and is done only in clinical studies [5].
Sex and contraception during treatment
What you should know
Sex is usually possible
Condoms
Contraception
Even with reduced fertility, pregnancy can happen, and some treatments harm an unborn baby or cause miscarriage. Ask your doctor which method you need and for how long after treatment [1].
Physical changes
In women, lower oestrogen from chemotherapy, hormone therapy or pelvic radiotherapy can lead to vaginal dryness and pain during sex [3]. In men, chemotherapy may lower sex drive during treatment but usually does not affect erections; pelvic radiotherapy, hormone therapy and pelvic surgery can cause erection problems [4].
Effective treatments
Pregnancy after cancer
Show detailsHide
For many survivors, pregnancy after treatment is possible. An important example is the POSITIVE study: 516 women aged 42 or younger with early hormone receptor-positive breast cancer paused their hormone therapy after 18 to 30 months to try for a pregnancy. About 3 in every 4 women who were followed became pregnant, and most of them had a baby. Breast cancer did not come back more often within 3 years than in women who had not paused treatment; that is, this short break did not raise the risk, at least in the first few years [9]. Longer follow-up is still needed, and the decision should be made with your oncologist.
For physicians
Guideline summary for physicians
- ASCO 2025 (fertility preservation): assess and counsel on fertility risks at diagnosis and during survivorship; refer interested or uncertain patients to a fertility specialist; discuss methods before treatment. In men: sperm cryopreservation before treatment and TESE if a semen sample is not possible; warn about a possibly higher risk of genetic damage in sperm collected soon after starting or finishing treatment; prepubertal testicular tissue cryopreservation only in trials. In women: embryo, oocyte and ovarian tissue cryopreservation, ovarian transposition and conservative gynaecological surgery; in vitro maturation of oocytes (IVM) as an emerging method. GnRHa should not replace established methods, but it can be offered as an adjunct in breast cancer and used to suppress menstruation in oncological emergencies. The only established method in prepubertal girls is ovarian tissue cryopreservation [5].
- Individual patient data meta-analysis of GnRHa in early breast cancer (873 patients, 5 trials): premature ovarian insufficiency 14.1% versus 30.9% (adjusted odds ratio 0.38); pregnancy after treatment 10.3% versus 5.5% (incidence rate ratio 1.83); no significant difference in disease-free or overall survival [7]. The POEMS trial was also done with goserelin alongside chemotherapy [8].
- ESMO 2020: guideline on fertility preservation and pregnancy after treatment in post-pubertal patients [6].
- ASCO 2018 (sexual problems): the care team should start the conversation about sexual health; psychosocial or psychosexual counselling should be offered to all patients; treatable medical factors should be addressed first. For vaginal atrophy, lubricants and moisturisers as first choice; low-dose vaginal oestrogen, lidocaine and DHEA in some cases. In men, PDE5 inhibitors and surgery in refractory cases. For vasomotor symptoms: CBT, paced breathing, hypnosis, venlafaxine and gabapentin [10].
When should I call my doctor?
- Before starting any treatment, if you are thinking about having children in the future; the chance to preserve fertility may be lost once treatment starts [5].
- If you think you might be pregnant during treatment (a late period or a positive test); some treatments harm an unborn baby [1].
- Unusual vaginal bleeding (outside your period or heavier than usual) during treatment [11].
- A temperature of 38 °C or higher during chemotherapy; this is an emergency [12].
- Pain, burning or unusual discharge from the genitals, or early menopause symptoms that disrupt daily life [1, 3].
Frequently asked questions
If my periods stop during chemotherapy, does it mean I cannot get pregnant?
Does fertility preservation delay cancer treatment?
Is pregnancy after hormone-positive breast cancer dangerous?
Related cancer types
Related guides
References
12 referencesShow all references, 6 with a study cardClose the reference list
Numbers in the text, such as [1], refer to these sources. Sources with a “Study card” button are summarised in the site’s evidence library.
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- 6Fertility preservation and post-treatment pregnancies in post-pubertal cancer patients: ESMO Clinical Practice Guidelines
- 7Gonadotropin-Releasing Hormone Agonists During Chemotherapy for Preservation of Ovarian Function and Fertility in Premenopausal Patients With Early Breast Cancer: A Systematic Review and Meta-Analysis of Individual Patient-Level Data
- 8Goserelin for Ovarian Protection during Breast-Cancer Adjuvant Chemotherapy
- 9Interrupting Endocrine Therapy to Attempt Pregnancy after Breast Cancer
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- 11Bleeding and Bruising (Thrombocytopenia) and Cancer Treatment
- 12Infection and Neutropenia during Cancer Treatment
This page is based on reputable scientific sources and was last updated on 28 October 2026. The content of this website is for educational and informational purposes only and does not replace consultation, diagnosis or treatment by a specialist physician. Consult your treating physician about any treatment decision.
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