Articles for young women / 17 Mar, 2020

Breast cancer treatment and fertility: what you need to know


Breast cancer is the most common type of cancer amongst Singaporean women, which is why it’s important to understand how treatments may affect your fertility. We’ve outlined what you need to know in the guide below.

Does breast cancer treatment affect my fertility?

Certain breast cancer treatments, such as chemotherapy and hormonal therapy may impact your ability to become pregnant.

Whether you are male or female, if you are considering having children, we recommend you speak with your cancer treatment practitioner before you begin any form of treatment.

Thankfully, fertility preservation methods such as embryo or egg freezing as well as ovarian tissue preservation make it possible to preserve your fertility before starting cancer treatment.

Do I need to get a fertility referral?

If you would like to have children in the future, it is important you talk through this with your oncologist before starting treatment. Your oncologist will be able to refer you to a fertility specialist so you can get all the information you need and any procedures before you start treatment.

A fertility specialist can answer any questions or concerns you have regarding getting pregnant in the future. They will advise you how best to preserve your fertility before commencing cancer treatment.

Questions you should ask your fertility specialist

  • I’d like to check my fertility levels before starting breast cancer treatment. Is this possible?
  • Does my age affect my fertility? In what way?
  • What will my chances of getting pregnant be after cancer treatment?
  • What are the best ways for me to preserve my fertility before cancer treatment?
  • Can you tell me what the fertility treatment process is and how it works?
  • Are different fertility methods more effective than others in preserving my fertility?

Female fertility explained

Every female is born with the total amount of eggs that her ovaries will hold for her entire lifetime.

Before puberty, a female has approximately 400,000 eggs and loses 11,000 of these each month. By puberty, her egg count has already decreased.

By the age of 30, women’s fertility decreases significantly, and by 40 years old, they have approximately 3% of their egg count. Egg quality also decreases.

Monthly, your ovaries release at minimum, one egg. Should a male’s sperm fertilise your egg, this egg becomes implanted into the womb. Should no fertilisation occur, you will have your period.

By menopause (approximately 51-years-old), the ovaries no longer release eggs. Women with the breast cancer gene will likely experience the onset of menopause sooner. After menopause, you are not able to get pregnant naturally.

The impact of chemotherapy on your fertility

Chemotherapy and fertility

The natural function of the ovaries is frequently affected by chemotherapy in pre-menopausal women. As a result, the quality and amount of eggs available is reduced and can lead to infertility.

Factors affecting future fertility:

  • Types of drugs used
  • Dosage given
  • Age
  • Fertility level before breast cancer treatment

We encourage you to discuss all possible avenues to preserve and protect your fertility before you begin cancer treatment. It ensures you have the best possible chance to get pregnant in the future.

Effects of chemotherapy 

There are several effective treatment paths for breast cancer all with varied side effects. The main ones that impact your fertility are alkylating agents—compounds preventing cancer cells multiplying. This group includes the drug cyclophosphamide, known to affect fertility.

Chemotherapy may also cause your period to stop; temporarily or permanently. For women under the age of 35, your period will likely resume. It is also not uncommon for your period to cease temporarily and commence after a few months or years post-cancer treatment.  Resumption of menstruation may not equate to fertility. Older women are more likely to be sub-fertile after chemotherapy for cancer treatment.

Females who undergo cancer treatment tend to experience menopause anywhere from 5-10 years earlier, which means the window to get pregnant after cancer treatment is much smaller.

It’s important to speak with your cancer treatment team to discuss the best course of action to preserve your fertility before cancer treatment and maximise your chances of a successful future pregnancy.

Is pregnancy possible during hormone therapy?

Women diagnosed with oestrogen receptor-positive cancer (ER+) will often undergo hormone therapy.

Options for preserving fertility

There are a variety of fertility options available in Singapore for preserving and protecting your fertility. These include embryo cryopreservation, oocyte cryopreservation and ovarian tissue preservation. Your Icon oncologist will be able to connect you in with fertility specialists for further information.

Breast cancer treatment and contraception

For women undergoing breast cancer treatment who would like to get pregnant, we advise you to discuss this with your oncologist so that a prudent plan for pregnancy can be put in place, taking into account risks of pregnancy as well as personal preferences, values and stage in your life. Certain types of cancer treatment can be harmful to an unborn baby, so it is important to consider contraceptive options in addition to discussion with your oncologist.

It is important to note women can get pregnant while on treatment provided they have completed at least 2-3 years of hormonal therapy and taking into account any other risk factors. A current international trial – Pregnancy Outcome and Safety of Interrupting Therapy for Women with Endocrine Responsive Breast Cancer (POSITIVE) trial is looking at the effects of hormone (otherwise known as endocrine) therapy interruption. Current retrospective evidence suggests that pregnancy after breast cancer does not increase the chances of breast cancer recurring. For women who want to get pregnant after breast cancer treatment, 5 – 10 years of hormone therapy may reduce the chances of conception. However, prospective study has not yet been carried out. POSITIVE trial looks at studying the breast cancer outcome after interrupting hormone therapy for women who wishes to get pregnant and had completed 2 – 3 years of therapy. Click here to find out more about the POSITIVE trial.

Men should consult with their specialist to explore non-hormonal contraceptive options, including condoms for men. For women, femidoms (female condoms) or a diaphragm are options. In some instances, an IUD (intrauterine device) may be suitable. You should consult with your treating practitioner to determine its suitability.

Singapore cancer support resources

Many helpful resources are available online or through your practitioner’s office to help you or your loved ones navigate cancer challenges. These links offer information for men and women covering mental health and wellbeing, diet and emotional support.