Breast Cancer Series

06 — Breast Cancer, Fertility, and the Unexpected Hope of Tomorrow

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Introduction: When Healing Demands a Different Kind of Courage

A breast cancer diagnosis during the reproductive years can fracture the future in ways that are difficult to explain to anyone who has not lived through it.

The immediate questions are usually about survival: What type of cancer is this? Has it spread? What treatment will I need? Will I need surgery, chemotherapy, radiation, hormone therapy, or targeted treatment?

But alongside those questions, another can quietly emerge:

Will I still be able to have children?

For some women, the possibility of losing fertility is one of the most painful consequences of treatment. Breast cancer does not necessarily take away the possibility of motherhood, but some cancer treatments can damage the ovaries, reduce the number of remaining eggs, or bring on temporary or permanent menopause.

That is why fertility belongs in the conversation before treatment begins whenever possible.

I was fortunate to have an oncologist who not only spearheaded my treatment but also gave me the freedom to ask questions. And boy, did I ask them.

That ability to ask — and to keep asking — mattered.

Today, fertility preservation is no longer an afterthought. Major oncology and reproductive-medicine organizations recommend discussing reproductive risks at diagnosis and revisiting fertility throughout survivorship. The field has also changed considerably: egg freezing, embryo freezing, ovarian tissue cryopreservation, ovarian suppression, and assisted reproductive technologies have expanded the possibilities available to many patients.

Science cannot promise every woman a future pregnancy.

But it can create possibilities that did not exist for previous generations.

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How Breast Cancer Treatment Can Affect Fertility

The ovaries contain a finite supply of immature eggs. Some cancer treatments can accelerate the loss of these follicles or damage ovarian function.

Chemotherapy is particularly important because certain chemotherapy regimens can cause chemotherapy-induced ovarian insufficiency. The risk varies considerably according to the woman's age, the chemotherapy drugs used, their doses, and the overall treatment plan.

Alkylating agents — particularly cyclophosphamide — are among the chemotherapy drugs most strongly associated with ovarian toxicity. Other agents, including anthracyclines and taxanes, may also contribute to reproductive toxicity, particularly when used as part of combination regimens.

The consequences can range from temporary menstrual changes to premature ovarian insufficiency (POI), in which ovarian function declines before the usual age of menopause.

Importantly, loss of menstruation during or immediately after chemotherapy does not automatically mean permanent infertility. Some women recover ovarian function after treatment, while others do not.

There is no single test immediately after chemotherapy that can guarantee whether a woman will or will not eventually conceive.

That uncertainty is one reason fertility preservation should be discussed before treatment whenever medically possible.

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Zoladex: Can Temporary Ovarian Suppression Help?

Zoladex (goserelin) is a gonadotropin-releasing hormone (GnRH) agonist.

During treatment, goserelin suppresses ovarian function and produces a temporary, medication-induced menopausal state. The idea is to place the ovaries in a relatively dormant state while chemotherapy is being administered.

The evidence is encouraging — but it needs to be described accurately.

In the landmark POEMS/S0230 trial, premenopausal women with early-stage, hormone-receptor-negative breast cancer received chemotherapy either alone or with goserelin. At two years, ovarian failure occurred in approximately 22% of women receiving chemotherapy alone compared with 8% of women receiving chemotherapy plus goserelin. Pregnancy was also reported more frequently in the goserelin group.

That is an important finding.

But goserelin is not a substitute for egg or embryo freezing.

Current ASCO guidance states that GnRH agonists may be offered as an adjunct for females with breast cancer, but they should not replace established fertility-preservation methods such as oocyte, embryo, or ovarian-tissue cryopreservation.

Goserelin can therefore be thought of as one additional tool, rather than a guarantee of fertility.

What treatment can feel like

Because goserelin suppresses ovarian hormone production, temporary menopausal symptoms can occur, including:

• Hot flashes

• Night sweats

• Vaginal dryness

• Changes in libido

• Mood changes

• Menstrual suppression

• Changes associated with reduced estrogen

For some women, menstruation eventually returns after treatment. For others, ovarian function remains impaired.

The outcome depends on many factors, particularly age and the intensity and type of cancer treatment.

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The Science of Fertility Preservation

When time and medical circumstances allow, fertility preservation should ideally be discussed before cancer treatment begins.

The principal established options include:

Oocyte Cryopreservation — Egg Freezing

Mature eggs are collected following controlled ovarian stimulation and then frozen, usually by a rapid-freezing technique called vitrification.

The eggs remain unfertilized.

One of the important advantages is that the woman retains future control over the choice of sperm used for fertilization.

Age at the time of egg freezing and the number of eggs successfully preserved are important factors in future reproductive potential.

Embryo Cryopreservation

Eggs are retrieved and fertilized with sperm before being frozen.

An embryo is not a zygote. A zygote is the single-cell stage immediately following fertilization; embryos used in fertility treatment are commonly cultured beyond this stage before cryopreservation.

Embryo cryopreservation is an established fertility-preservation technique and can offer relatively predictable outcomes based on factors such as age, embryo number, and embryo quality.

Ovarian Tissue Cryopreservation

A portion of ovarian tissue containing thousands of follicles can be surgically removed and cryopreserved.

This option is particularly important when there is not enough time to undergo ovarian stimulation and egg retrieval before cancer treatment, and it can also be used in situations where ovarian stimulation is not appropriate.

The field has advanced considerably. In its current guidance, the American Society for Reproductive Medicine no longer considers ovarian tissue cryopreservation an experimental technique.

In selected patients, the stored tissue may later be transplanted to restore ovarian function and potentially allow pregnancy.

However, ovarian tissue transplantation requires careful consideration in cancer survivors because of the possibility of malignant cells being present in the tissue, depending on the original cancer. This is a specialized decision requiring coordination between reproductive specialists and the oncology team.

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There Is No Single “Best” Fertility-Preservation Method

Egg freezing, embryo freezing, and ovarian tissue cryopreservation are not competing answers to the same question.

The appropriate approach depends on:

• Age

• Ovarian reserve

• Cancer type and stage

• Planned chemotherapy

• How urgently treatment must begin

• Whether ovarian stimulation is medically appropriate

• Whether sperm from a partner or donor is available

• Personal, ethical, financial, and family circumstances

• The woman's own reproductive goals

Modern fertility preservation is therefore less about choosing a universally superior method and more about creating the widest reasonable range of future possibilities.

That conversation should happen with both the cancer team and a reproductive specialist.

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What Happens After Chemotherapy?

One of the most important messages for younger breast cancer patients is this:

Amenorrhea is not the same thing as a final verdict on fertility.

Some women resume menstrual cycles after chemotherapy. Others experience prolonged ovarian dysfunction or permanent menopause.

Recovery is influenced by age, ovarian reserve, chemotherapy regimen and cumulative dose, and other aspects of treatment.

And menstruation itself is not a perfect measure of fertility. A woman can menstruate and still have diminished ovarian reserve, while another woman may experience temporary amenorrhea and later recover ovarian activity.

This is why fertility assessment after treatment may include reproductive history, hormone testing, ovarian-reserve assessment, imaging, and consultation with a fertility specialist.

There is also an important distinction between ovarian function and the ability to become pregnant. Preserving ovarian activity does not guarantee pregnancy, just as the absence of menstruation immediately after treatment does not prove that pregnancy will never be possible.

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The Possibility of Pregnancy After Breast Cancer

For many survivors, pregnancy after breast cancer is possible.

The question is not simply whether the ovaries are functioning. The oncology team must also consider the original cancer, its hormone-receptor status, the treatments received, the time elapsed since treatment, and whether additional therapy is still required.

For women with hormone-receptor-positive breast cancer, endocrine therapy such as tamoxifen or an aromatase inhibitor may be prescribed for years. These treatments are important parts of breast-cancer management but are not compatible with pregnancy while being taken.

The POSITIVE trial provided important prospective evidence concerning temporary interruption of endocrine therapy to attempt pregnancy in selected women with hormone-receptor-positive early breast cancer. The study enrolled women aged 42 or younger who had completed 18–30 months of endocrine therapy and wished to become pregnant. The findings provided reassuring short-term evidence regarding breast-cancer outcomes during the study period, although longer follow-up remains important.

This does not mean that every woman with hormone-receptor-positive breast cancer should stop endocrine therapy to become pregnant.

It means that, for appropriately selected women, pregnancy can become part of a carefully planned survivorship conversation.

That decision belongs with the woman and her oncology and reproductive-care teams.

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Genetics: Another Conversation Worth Having

For younger women diagnosed with breast cancer, genetic counseling may be particularly important.

Inherited pathogenic variants in genes such as BRCA1 and BRCA2 can increase the risk of breast and ovarian cancers and may have implications for family planning.

Genetic counseling can help patients understand:

• Whether genetic testing is appropriate

• What an inherited result could mean for relatives

• Whether reproductive genetic testing may be relevant

• How inherited cancer risk might influence future medical decisions

• What reproductive options are available

For some families, assisted reproductive technology may include preimplantation genetic testing for a monogenic condition (PGT-M) when an inherited pathogenic variant has been identified.

These are highly personal decisions. Genetic counseling allows them to be made with a clearer understanding of the science.

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What About Diet, Supplements, and “Improving Egg Quality”?

This is an area where hope can easily outrun evidence.

There is no diet proven to restore ovarian reserve after chemotherapy, and there is no supplement that can guarantee future fertility.

A nutritious diet, adequate protein, regular physical activity, appropriate calcium and vitamin D intake, adequate sleep, and avoidance of smoking are sensible components of overall survivorship care.

But claims that particular supplements — including CoQ10, NAC, or myo-inositol — can restore fertility after cancer treatment should be treated cautiously.

Supplements can interact with cancer treatments, medications, surgery, or other aspects of medical care.

For a cancer survivor, “natural” should never automatically mean “safe.”

Any supplement should be discussed with the oncology team or another qualified clinician who knows the patient's treatment history.

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Fertility Is Part of Cancer Survivorship

Fertility preservation should not be treated as a single conversation that happens before the first chemotherapy infusion and then disappears.

The 2025 ASCO guideline update specifically emphasizes fertility assessment and counseling both at diagnosis and during survivorship. It recognizes that patients may still have fertility-related needs after treatment has ended and that preservation or reproductive options may remain relevant later.

That is an important evolution in cancer care.

Survival is not the end of the story.

For a young woman, survivorship can mean asking:

Can I have children?

Can I safely become pregnant?

Can I carry a pregnancy?

Could I use eggs or embryos that were preserved before treatment?

What happens if my ovaries no longer function?

What are my options if pregnancy is not possible?

Those questions deserve space in the room.

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The Heart of It All: Hope With Science Behind It

Cancer can change the future without completely erasing it.

For some women, fertility returns unexpectedly. For others, fertility preservation before treatment becomes the bridge to parenthood. Some will use previously frozen eggs or embryos. Others may pursue donor eggs, donor embryos, adoption, or other paths to building a family.

And some will discover that motherhood takes a form they never anticipated.

There is no single definition of what it means to become a mother.

But there is something profoundly important about knowing that a breast cancer diagnosis does not automatically close every door to the future.

The most powerful form of hope is not a promise that everything will work out exactly as imagined.

It is knowing that there may still be possibilities.

And sometimes, science is what makes those possibilities visible.

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A Question Worth Asking Before Treatment

If you are a young woman newly diagnosed with breast cancer and future pregnancy matters to you, one of the most important questions you can ask is:

“Could my treatment affect my fertility, and should I see a fertility specialist before we begin?”

Ask it early.

Ask it even if you are unsure whether you want children.

Ask it even if the diagnosis has left you unable to think beyond tomorrow.

You do not have to decide your entire future at once.

You simply need to know what choices may exist.

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Final Word

Cancer treatment is about saving life.

But survivorship is also about asking what that life might look like afterward.

For some women, that future may include children. For others, it may not. For some, motherhood will happen biologically; for others, through assisted reproduction, adoption, or another deeply personal path.

The important thing is that the conversation is not silenced by the diagnosis.

Ask the question.

Preserve what can be preserved.

Leave room for tomorrow.

Because sometimes the most unexpected part of surviving cancer is discovering that the future still has something to say.

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References

1. American Society of Clinical Oncology. Fertility Preservation in People With Cancer: ASCO Guideline Update.Journal of Clinical Oncology. 2025.

2. American Society for Reproductive Medicine. Fertility Preservation in Patients With Medical Indications: A Committee Opinion. Fertility and Sterility. 2026;125:247–259.

3. Moore HCF, Unger JM, Phillips K-A, et al. Goserelin for ovarian protection during breast-cancer adjuvant chemotherapy. New England Journal of Medicine. 2015;372:923–932.

4. National Cancer Institute. Treatment Helps Preserve Fertility for Some Women With Breast Cancer. 2015.

5. Oktay K, Harvey BE, Partridge AH, et al. Fertility Preservation in Patients With Cancer: ASCO Clinical Practice Guideline Update. Journal of Clinical Oncology. 2018;36:1994–2001.

6. Partridge AH, et al. Interrupting Endocrine Therapy to Attempt Pregnancy after Breast Cancer. New England Journal of Medicine. 2023;388:1645–1656.

7. American Cancer Society. Pregnancy and Breastfeeding After Breast Cancer.

8. American Cancer Society. Preserving Your Fertility When You Have Cancer.

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Glossary

ART — Assisted Reproductive Technology
Medical procedures used to assist conception, including in vitro fertilization.

BRCA1 / BRCA2
Genes involved in DNA repair. Certain inherited pathogenic variants substantially increase the risk of breast and ovarian cancers.

ER-positive (ER+)
A breast cancer whose cells express estrogen receptors.

GnRH — Gonadotropin-Releasing Hormone
A hormone involved in regulating reproductive function through the hypothalamic-pituitary-gonadal axis.

GnRH agonist (GnRHa)
A medication that initially stimulates and then suppresses reproductive hormone signaling. Goserelin is one example.

IVF — In Vitro Fertilization
A fertility treatment in which eggs are fertilized outside the body before resulting embryos may be transferred to the uterus.

Oocyte
An immature female germ cell; in fertility treatment, the term commonly refers to an egg collected for cryopreservation or fertilization.

Oocyte cryopreservation
Freezing of unfertilized eggs for potential future use.

POI — Premature Ovarian Insufficiency
Loss or marked reduction of normal ovarian function before age 40.

PGT-M — Preimplantation Genetic Testing for a Monogenic Condition
Genetic testing of embryos created through IVF for a specific inherited genetic condition.

PR-positive (PR+)
A breast cancer whose cells express progesterone receptors.

Ovarian tissue cryopreservation
Removal and freezing of ovarian tissue containing follicles for potential future transplantation or other reproductive use.

Zoladex (goserelin)
A GnRH agonist used in breast cancer treatment for ovarian suppression and, in appropriate patients, as an adjunct intended to reduce the risk of chemotherapy-induced ovarian insufficiency.

 

Glossary of Abbreviations