Hormone therapy breast cancer Paris — tamoxifen, aromatase inhibitors

THE ESSENTIALS

Key points in 30 seconds

Indication: hormone-dependent breast cancer (positive hormone receptors ≥ 10%) — about 80% of cases. Indication not influenced by HER2 status.
3 families: tamoxifen (premenopausal), aromatase inhibitors — anastrozole, letrozole, exemestane (postmenopausal), LH-RH agonists (ovarian function suppression).
Duration: 5 years standard, extended to 7-10 years if your recurrence risk is higher.
Introduction: tamoxifen after radiotherapy; aromatase inhibitors and LH-RH agonists may be given concurrently with radiotherapy.
Side effects: hot flashes, vulvovaginal dryness, arthralgia (aromatase inhibitors), bone loss, mood changes — manageable with appropriate care.

KEY FIGURES

Key figures — Hormone therapy

Statistics in figures to understand the topic at a glance.

80%

of breast cancers are hormone-dependent

~40%

reduction in 15-year recurrence risk

5 yrs

standard recommended duration

7-10 yrs

recommended extension if high risk

3 AIs

anastrozole, letrozole, exemestane — interchangeable

20-50%

patients with arthralgia under aromatase inhibitor

20 mg/d

standard tamoxifen dose (1 tab/day)

/28 d

LH-RH agonist injection (monthly)

/18 mo

DXA scan frequency under aromatase inhibitor

2 yrs

abemaciclib duration

12 mo

olaparib duration (OlympiA, BRCA)

100%

covered by French healthcare (ALD 30)

Section 01 · Understand

Hormone therapy in breast cancer

For 80% of breast cancers, surgery (lumpectomy or mastectomy) is not enough on its own. Depending on your situation, treatment may combine several approaches: radiotherapy, chemotherapy, immunotherapy, targeted therapies — and hormone therapy. The latter, a medication taken for 5 to 10 years, significantly reduces the risk of recurrence and mortality. It is not chemotherapy: these are tablets (or monthly injections), taken at home, every day.

So-called hormone-dependent breast cancer is driven by female hormones — estrogens and progesterone. Hormone therapy works by blocking this hormonal stimulation, either at the level of the tumor receptor, or by preventing estrogen production. It is one of the most effective treatments medicine can offer in breast cancer.

The indication is set according to three criteria analyzed on your pathology report: estrogen receptors (ER), progesterone receptors (PR) and — to guide the associated strategy — HER2 status and Ki67. The indication for hormone therapy is not influenced by HER2 status: a HER2+ cancer that is also hormone-dependent will receive hormone therapy.

My role at this stage: to explain why this treatment is being offered to you, to help you understand both the benefits and side effects, and to work closely with the medical oncologist who will oversee prescription and follow-up. Adherence is critical — stopping treatment early significantly reduces its effectiveness.

These recommendations are based on the French INCa 2025 guidelines and the SénoriF 2025-2026 reference, updated based on the TEXT, SOFT, MA17, ATAC, BIG 1-98, ATLAS, aTTom, MonarchE, NATALEE and OlympiA trials.

Section 02 · The molecules

Four families of medications

Hormone therapy is not a single drug. Depending on your menopausal status, your tumor profile and your tolerance, several molecules — or combinations — are possible. All are covered at 100% under the French long-term illness scheme (ALD 30).

Here are the four major families of adjuvant hormone therapy. The preoperative consultation is the opportunity to discuss the option best suited to your situation. For advanced indications (high-risk cancers, BRCA mutations), combinations with other targeted treatments are also possible.

SERM

Tamoxifen

Nolvadex® 20 mg, 1 tab/day in the evening. Selective estrogen receptor modulator. The reference treatment in premenopausal women.

AIs

Aromatase inhibitors

Anastrozole (Arimidex®), letrozole (Femara®), exemestane (Aromasin®). 1 tab/day. For postmenopausal women. The 3 AIs are clinically interchangeable.

Ovarian suppression

LH-RH agonists

Goserelin (Zoladex®), leuprorelin (Enantone®), triptorelin (Decapeptyl®). Monthly subcutaneous or IM injection. Reversible ovarian suppression.

Combinations Innovation

Targeted combinations

Abemaciclib, ribociclib — CDK4/6 inhibitors; olaparib — PARP inhibitor in BRCA carriers. Added to hormone therapy for high-risk cancers.

A word on tolerance

Many patients consider stopping treatment because of poor tolerance — hot flashes, joint pain, fatigue, dryness, weight gain, mood changes. This is common and understandable, but you should never stop on your own: it is often possible to switch molecules, adjust the dose, or add symptomatic treatment.

The best way to tolerate treatment over time is daily physical activity: 30 minutes a day is enough. It reduces joint pain, improves mood, limits weight gain, preserves bone density, and — additional benefit — reduces the recurrence risk by approximately 25% on its own. Brisk walking, swimming, cycling, yoga: the discipline matters less than regularity.

Section 03 · Indications

By profile

There is not one hormone therapy, but several.

The choice of molecule, duration, and possible combinations depends on several factors examined together in consultation: your menopausal status at diagnosis — a major criterion, since chemotherapy-induced amenorrhea is not sufficient to define menopause — the stage of your cancer (T, N), the biological profile (hormone receptors, grade, Ki67), and the residual risk after local treatment.

To this are added your medical history (thrombosis, osteoporosis, gynecological disorders, BRCA mutation), your personal tolerance to the different molecules, and your life plans — fertility, profession, quality of life.

Every prescription is validated at the breast cancer MDT meeting, followed up jointly with a referring medical oncologist. Here are the six main prescription scenarios.

Pathology report — hormone receptors, HER2, Ki67

The starting point

Understanding your pathology report

The pathology report determines the indication for hormone therapy. Hormone receptors, HER2, Ki67 — learn how to read your result.

Premenopausal patient

Tamoxifen for 5 years is the reference treatment in premenopausal women. It blocks the action of estrogens at the tumor receptor level, without stopping the ovaries from producing hormones.

Why combine an LH-RH agonist with an aromatase inhibitor? In premenopausal women, the ovaries still produce estrogens. But aromatase inhibitors only work when ovarian production has stopped — they only block residual production (from fat, adrenal glands, peripheral tissues). So we first put the ovaries at rest using an LH-RH agonist (goserelin, leuprorelin, triptorelin — monthly or quarterly injection). Once the ovaries are blocked, the aromatase inhibitor can then act on the residual production. This is intensified hormone therapy: it is offered when the recurrence risk is higher (larger tumor, lymph node involvement, certain tumor profiles) or in case of associated chemotherapy. The expected benefit is a further reduction in recurrence risk, at the cost of more pronounced side effects (artificial menopause, hot flashes, bone loss).

Fertility preservation is discussed before starting treatment. Non-hormonal contraception (copper IUD) is required throughout treatment because tamoxifen is teratogenic, and induced amenorrhea does not guarantee absence of ovulation.

Monitoring under tamoxifen

Annual pelvic ultrasound

Under tamoxifen, I systematically request a transvaginal pelvic ultrasound once a year. This examination monitors the endometrium, because tamoxifen has an estrogenic effect on the uterus (while it blocks estrogens at the breast level).

The most frequent change is glandulo-cystic hyperplasia of the endometrium: the uterine mucosa thickens and shows small fluid-filled cavities (cysts). This image is characteristic of tamoxifen and not dangerous in itself — it is an expected effect of the treatment. It generally requires no intervention. However, in case of post-menopausal bleeding or imaging doubt, a gynaecological consultation with possible hysteroscopy is indicated to rule out atypical hyperplasia or endometrial cancer (rare but possible under tamoxifen).

Menopause

Postmenopausal patient

Aromatase inhibitor for 5 years is the reference option: anastrozole, letrozole, or exemestane — interchangeable. Tamoxifen remains possible if the risk is low or if tolerance to aromatase inhibitors is poor (disabling joint pain, rapid bone loss). A bone density scan (DEXA) is required before starting and every 18 months under aromatase inhibitor.

Transition

Perimenopausal patient

A switch from tamoxifen to an aromatase inhibitor is possible once menopause is confirmed. Hormone testing (FSH, estradiol) can help confirm menopausal status before switching. No rush: we wait until menopause is genuinely established.

Beyond 5 years

Extension to 7-10 years

An extension may be offered when the residual risk is higher. The decision is made at 5 years, taking into account tolerance, recurrence risk (initial tumour characteristics, lymph node involvement), and quality of life. The benefit persists long-term: the reduction in recurrence risk continues well beyond the end of treatment.

≥ 70 years

Elderly patient

Emphasis is on quality of life and tolerability. A geriatric assessment helps choose the most appropriate molecule, and tamoxifen is favoured if aromatase inhibitors are poorly tolerated. Follow-up is closer in case of cardiovascular or bone comorbidities.

Male

Male breast cancer

Tamoxifen remains the reference molecule in men, whose breast cancer is almost always hormone-dependent. Aromatase inhibitors are not used first-line because they do not suppress hormonal production of testicular origin. Oncogenetic counselling is systematically offered.

Day-to-day

What it actually looks like

Beyond the name of the drug, what really matters is: how you take it, what tests are done before, and how it will be monitored. Here are the 4 treatments explained simply, the way we talk about them in consultation.

Premenopausal women · reference option

Tamoxifen (Nolvadex®)

One tablet a day, at the same time. Most women take it in the evening — recent data suggest that an end-of-day dose is slightly better tolerated. It is introduced after radiotherapy is over, never at the same time.

Before starting, we plan a gynaecological exam with a pelvic ultrasound to have a baseline image of the uterus. During treatment, I systematically request a transvaginal pelvic ultrasound once a year, in addition to the annual gynaecological follow-up. This examination monitors the endometrium and detects early any expected changes under tamoxifen (glandulo-cystic hyperplasia) or, more rarely, suspicious changes.

Tamoxifen is also the reference treatment for men with breast cancer, and for women who can't tolerate aromatase inhibitors.

Postmenopausal women · reference option

Aromatase inhibitors (anastrozole, letrozole, exemestane)

Same idea — one tablet a day. Three different molecules exist — Arimidex®, Femara®, Aromasin® — all equally effective. Switching from one to another is perfectly possible if tolerance isn't good with the first.

The treatment can be started at the same time as radiotherapy, without added risk. Before starting, we do a DXA scan to get a baseline on bone strength, a lipid panel, and a vitamin D level.

During treatment: a DXA scan every 18 months, a lipid panel yearly. We recommend 800 to 1200 mg of calcium per day in your diet, and vitamin D if needed.

Putting the ovaries to rest · premenopausal women

LH-RH agonists

A subcutaneous or intramuscular injection every 4 weeks. Three products exist — Zoladex®, Enantone®, Decapeptyl® — all equivalent.

The principle: putting the ovaries to rest to induce an artificial menopause which is reversible — meaning ovarian function comes back after the treatment stops. This makes it possible to use an aromatase inhibitor in a woman who isn't yet menopausal.

Indicated when clinical risk is high, or when an aromatase inhibitor alone is poorly tolerated. Bone follow-up is the same as for aromatase inhibitors (DXA every 18 months). For some patients — especially BRCA carriers — a surgical removal of the ovaries may be discussed as a definitive alternative.

Higher-risk cancers · innovations

Targeted combinations

For some cancers carrying a higher risk of recurrence, a second targeted treatment is combined with hormone therapy. These regimens have brought very encouraging results in recent years.

Abemaciclib — one tablet twice a day for 2 years, on top of hormone therapy. For cancers with significant lymph node involvement. Ribociclib — another option, over 3 years, currently being rolled out. Both belong to the same family (CDK4/6 inhibitors).

Olaparib — one tablet twice a day for 12 months. Reserved for patients carrying a BRCA1 or BRCA2 mutation with a high-risk cancer. It's a PARP inhibitor.

The choice between these medications is made at multidisciplinary team meeting, after analysis of your pathology report, and then discussed with you. It can always be adjusted if tolerance isn't right — there's almost always an alternative.

Section 04 · Side effects

Understanding and managing side effects

Adherence is half the effectiveness of the treatment.

Many patients — up to 30 to 40% according to studies — stop their hormone therapy prematurely, mainly because of side effects. That is a pity: these effects can be managed, and premature discontinuation significantly reduces the benefit of treatment.

Here are the six major categories of side effects and their management — based on the SénoriF 2025-2026 recommendations and learned societies (French Rheumatology Society, AFSOS).

Aromatase inhibitors

Joint pain

Very common under aromatase inhibitors. Switching between the 3 molecules often helps a lot. Physical activity, yoga and acupuncture do too. Medication can be prescribed when needed.

All molecules

Hot flashes

Lifestyle, physical activity, hypnosis and acupuncture all help. Medication can be added if the discomfort is significant. Phytoestrogens remain off-limits.

Quality of life

Vulvovaginal dryness

Simple non-hormonal local care first (hyaluronic acid, coconut oil). A local hormone treatment can be added later, in agreement with your oncologist.

AIs / LH-RH

Bone loss

Bone density check every 18 months. Calcium and vitamin D intake. An IV treatment can be added if the risk is higher, after a dental check-up.

Tamoxifen

Endometrial risk

Uterine polyps (often benign, frequent) and — more rarely — endometrial cancer. Systematic pelvic ultrasound once a year throughout treatment, to detect any anomaly early.

Tamoxifen

Thromboembolic risk

Mild increase in risk of phlebitis/pulmonary embolism. Caution in case of personal or family thromboembolic history. Mobility, hydration, clinical follow-up.

Action plan — you are not alone

How to manage side effects

Hormone therapy can be difficult, this should not be downplayed. But no patient should suffer in silence. Five concrete levers exist — used alone or in combination. The goal is to complete the 5 years (or more) without giving up after 6 months — and several levers exist to make this possible.

01

Adapted physical activity

High level of evidence — NCCN category 1

Physical activity reduces arthralgia (joint pain) by 30 %, hot flushes by 25 %, and improves mood, sleep, and fatigue. It is the only non-pharmacological intervention validated at this level by all international guidelines (ESMO 2024, NCCN 2025, NICE 2024).

Minimum target: 150 minutes per week of moderate aerobic activity (brisk walking, cycling, swimming) + 2 strength training sessions per week. The HOPE study (2024) confirms that a structured 12-week programme significantly reduces joint pain under aromatase inhibitors.

Good to know

If you have never exercised: 30 minutes of brisk walking per day is enough to start. Your medical oncologist can refer you to a structured exercise oncology programme.

02

Switching medication or therapeutic pause

Validated strategy — ESMO 2024 guidelines

Not all medications are equal for you. If a major intolerance persists after 3 months, several options should be discussed in consultation:

Switch between aromatase inhibitors (letrozole → anastrozole → exemestane): different toxicity profiles, 30 to 50 % improvement reported.
Switch tamoxifen ↔ aromatase inhibitor depending on your menopausal status and tolerance.
Therapeutic pause of 4 to 8 weeks in case of severe toxicity, followed by gradual resumption: often allows much better tolerance afterwards.

Important

Never stop on your own. Any change must be discussed in consultation with your medical oncologist. A supervised pause does not compromise your prognosis; an abrupt, non-discussed stop does.

03

Targeted symptomatic treatments

For every symptom — a dedicated solution

Hot flushes

Venlafaxine (37.5–75 mg), gabapentin, oxybutynin, acupuncture, hypnosis. No hormonal HRT (absolute contraindication).

Vaginal dryness & intimate pain

Water- or silicone-based lubricants, hyaluronic acid gels (Mucogyne, Cicatridine). Ultra-low-dose vaginal oestrogens discussed case by case with your oncologist.

Arthralgia (joint pain)

Exercise +++, targeted physiotherapy, level 1 analgesics, vitamin D (frequent deficiency), acupuncture (moderate evidence).

Bone health & osteoporosis (AI)

DEXA scan every 2 years, systematic vitamin D + calcium supplementation, bisphosphonates or denosumab if T-score < –2.

04

Psychological support & sex therapist

Transversal support — often essential

Hormone therapy spans the next 5 or 10 years. The psychological and relational impact is real: loss of libido, body image changes, recurrence anxiety, mental fatigue, withdrawal, irritability.

Psycho-oncologist: reimbursed consultations in cancer centres or private practice.
Sex therapist specialised in oncology: couple-based approach, restoration of intimacy. Vaginal dryness is not inevitable.
Patient peer groups: Europa Donna, Breast Cancer Now. Sharing with women who have lived the same experience changes everything.
Cognitive behavioural therapy for insomnia (CBT-I): reference treatment for sleep disturbance under hormone therapy (2024 meta-analysis).

05

Supportive care across the board

Everything that makes daily life better

Targeted physiotherapy

Joint pain, stiffness, lymphatic drainage if needed. Prescription available.

Nutrition

Dietitian for weight gain (frequent), alcohol reduction (max 3 drinks/week), evidence-based Mediterranean diet.

Mindfulness & medical hypnosis

Reduces hot flushes, anxiety, sleep problems. Often as adjuvant.

Care coordinator nurse

Point of contact between consultations. Ask for one at your centre.

Keep a symptom journal.

Track for 3–4 weeks what bothers you most (intensity 1–10, time of day, context). Bring it to your oncology consultation: 5 minutes of concrete discussion are worth more than 30 minutes of vague questions. And above all — no patient should grit her teeth in silence for 5 years. If you suffer, we act.

Section 05 · Your pathway

Your pathway, step by step

From prescription to multi-year follow-up, here are the key steps of the hormone therapy pathway. Each step is an opportunity for evaluation, adjustment, and shared decision-making.

01

Breast MDT meeting

The indication for hormone therapy is validated at the multidisciplinary meeting based on biological profile (ER, PR, HER2, Ki67), stage, and your menopausal status. A possible combination (CDK4/6, PARP) is also discussed.
02

Baseline workup

Before starting: gynecological examination + pelvic ultrasound (tamoxifen), DXA + lipid panel + 25-OH-D3 (aromatase inhibitor / LH-RH), CBC and liver function tests. Mandatory dental check-up if bisphosphonates planned.
03

Prescribing consultation

With the medical oncologist: choice of molecule, practical intake instructions, side-effect anticipation, provision of a patient information booklet (Institut Curie, INCa). A 6-month prescription is usually issued.
04

Starting treatment

Tamoxifen: after radiotherapy. Aromatase inhibitors / LH-RH agonists: possible concurrently with radiotherapy. First clinical check-up at 3 months to assess tolerance.
05

Regular monitoring

Consultations every 6 months (breast surgeon/medical oncologist alternating). Annual gynecological examination. Annual mammogram. DXA every 18 months under AI/LH-RH. Blood tests as needed.
06

Reassessment at 5 years

Discussion of an extension to 7-10 years based on residual risk ( or. Switch possible (tamoxifen ↔ aromatase inhibitor) if menopausal status evolves or in case of intolerance.

Section 06 · Documents & resources

Useful documents

To prepare your consultation, understand your treatment, or follow up your aftercare, here are the documentary resources I make available to you.

Your questions

Frequently asked questions about hormone therapy

The questions patients ask most often — before starting, during treatment, or simply to understand what is happening. If yours is not here, it will find its answer in consultation.

What is hormone therapy for breast cancer?▾

Hormone therapy is a drug treatment that blocks the action of estrogens on tumor cells expressing hormone receptors. It only concerns so-called "hormone-dependent" breast cancers — around 80% of breast cancers. It is prescribed in addition to surgery to significantly reduce the risk of recurrence and mortality.

Who is hormone therapy indicated for?▾

Adjuvant hormone therapy is recommended for all patients with invasive with estrogen receptors ≥ 10% breast cancer. For estrogen-receptor positive cancers between 1% and 9%, the indication is discussed on a case-by-case basis, especially if PR ≥10% or a luminal molecular profile. For very small tumors (very small tumor without lymph node involvement), the risk/benefit balance may justify abstention. The indication is not influenced by HER2 status.

What is the difference between tamoxifen and aromatase inhibitors?▾

Tamoxifen is a selective estrogen receptor modulator (SERM): it blocks the estrogen receptor at the breast level, but may have estrogen-like effects elsewhere (uterus, bone). It is mainly used in premenopausal women (20 mg/day in the evening, orally). Aromatase inhibitors (anastrozole, letrozole, exemestane) block estrogen production by preventing the conversion of androgens into estrogens by aromatase. They are effective only in postmenopausal women, as they do not act on ovarian production. The 3 aromatase inhibitors are clinically interchangeable.

How long does hormone therapy last?▾

The standard duration is 5 years. If your recurrence risk is higher (larger tumour, lymph node involvement, certain tumour characteristics), an extension to 7-10 years may be recommended after reassessment of the risk/benefit ratio at 5 years. This decision is supported by the.com/) in postmenopausal women under aromatase inhibitor. In men, tamoxifen remains the reference for at least 5 years.

What are the side effects of tamoxifen?▾

The main side effects are hot flashes, vulvovaginal dryness, menstrual cycle disturbances, mild weight gain, hepatic steatosis (rare), and hypertriglyceridemia. Tamoxifen increases the risk of uterine polyps and endometrial cancer (rare) — that is why annual gynaecological follow-up is mandatory, with a systematic pelvic ultrasound once a year. There is also an increased risk of venous thromboses, requiring caution in case of thromboembolic history.

What are the side effects of aromatase inhibitors?▾

The most common side effects are joint and muscle pain (arthralgia, stiffness) — 20 to 50% of patients according to studies. Hot flashes, vulvovaginal dryness, and especially bone loss are also added — which may progress to osteoporosis — hence the need for a DXA scan at baseline and then every 18 months and for calcium and vitamin D supplementation. An annual lipid panel is also recommended. Switching between the 3 aromatase inhibitors can improve tolerance.

What if I cannot tolerate the side effects?▾

Several solutions exist. The first: switching molecule (between the 3 aromatase inhibitors, or switching to tamoxifen in case of major intolerance). Non-drug approaches have proven their worth: regular physical activity, yoga, acupuncture, mindfulness meditation, psychological support. For arthralgia, duloxetine 30 to 60 mg/day can be offered. For hot flashes, venlafaxine is an option (but mind interactions with tamoxifen). For vulvovaginal dryness, non-hormonal local care first (hyaluronic acid, coconut oil), then local hormone treatment as second line. Premature discontinuation should never be decided alone — it significantly reduces the efficacy of the treatment.

Can hormone therapy be started during radiotherapy?▾

Tamoxifen must be started after radiotherapy is completed, due to a potential risk of increased skin and lung toxicity (Pierce 2005; Yavas 2013). In contrast, aromatase inhibitors and LH-RH agonists may be started concurrently with radiotherapy — their concurrent use does not appear to increase irradiation toxicity (Azria 2010; Ishitobi 2014).

What if I am premenopausal at diagnosis?▾

It is the "premenopausal" status at diagnosis, before chemotherapy, that is taken into account for the choice of hormone therapy — chemotherapy-induced amenorrhea is not sufficient as a menopause criterion. For a premenopausal patient at low clinical risk, tamoxifen alone or the LH-RH agonist + aromatase inhibitor combination is offered for 5 years. For a patient at high risk (indication for chemotherapy, high clinical risk), the LH-RH agonist + aromatase inhibitor combination is recommended.

Can hormone therapy be given before surgery (neoadjuvant)?▾

Yes, in some situations. Neoadjuvant hormone therapy has not demonstrated in randomized trials its equivalence with upfront surgery, but pilot studies suggest its equivalence in terms of breast conservation compared with chemotherapy in postmenopausal women, for a duration of at least 16 weeks. It can be offered in particular to elderly or frail patients, or to shrink a luminal A hormone-dependent tumor before breast-conserving surgery. The decision is always multidisciplinary.

When should a CDK4/6 inhibitor be combined with hormone therapy?▾

Abemaciclib is indicated in combination with hormone therapy for 2 years in hormone-dependent HER2 negative breast cancer patients at high risk: significant lymph node involvement. Ribociclib has obtained an extended marketing authorization for 3 years (lymph node involvement or larger tumor size) — subject to reimbursement (not granted at the end of 2025). Palbociclib has no indication in the adjuvant setting. These treatments are to be started after radiotherapy.

And olaparib in case of BRCA mutation?▾

Olaparib (PARP inhibitor) is indicated in combination with hormone therapy for 12 months in BRCA1/BRCA2-mutated patients with HER2- early breast cancer at high risk, after neoadjuvant or adjuvant chemotherapy. For hormone-dependent breast cancer also eligible for a CDK4/6 inhibitor, olaparib is preferred due to the demonstrated overall survival gain. To be started after radiotherapy.

Is gynecological monitoring required under hormone therapy?▾

Yes, systematically. Under tamoxifen: an annual gynaecological examination and a systematic annual pelvic ultrasound to monitor the endometrium. Under aromatase inhibitor: annual gynecological monitoring as well, with hormone assays (FSH, LH, E2) in case of bleeding or signs of estrogen impregnation possibly suggesting a resumption of ovarian function. Vulvovaginal dryness is common and must be managed.

What bone follow-up under aromatase inhibitor or ovarian suppression?▾

A DXA scan is mandatory at baseline, then repeated every 18 months for 5 years depending on context. Vitamin D (25-OH-D3) measurement is requested at baseline and supplemented as needed. A calcium intake of 800 to 1200 mg/day is recommended. In postmenopausal patients at high risk of recurrence, bisphosphonate therapy (zoledronate 4 mg IV every 6 months for 3 years) may be offered as an adjuvant — with a mandatory dental check-up beforehand.

Is hormone therapy covered at 100%?▾

Yes. In France, breast cancer is a long-term illness (ALD 30), and all cancer-related treatments — including hormone therapy and monitoring tests — are covered at 100% by the French health insurance system on the basis of the Social Security rate. Hormone therapy drugs (tamoxifen, aromatase inhibitors) are reimbursed at 100%.

Can I ask for a second opinion on a hormone therapy prescription?▾

Yes, this is legitimate and common. A second-opinion consultation can be arranged with a medical oncologist or a breast surgeon, bringing along your pathology report, your receptor profile (ER, PR, HER2, Ki67), and the conclusions of the MDT meeting. The risk/benefit ratio, choice of molecule, duration of treatment and management of side effects can all be discussed again.

COMPARISON

Comparison: tamoxifen vs aromatase inhibitors

Criterion	Tamoxifen	Aromatase inhibitors (AIs)
Mechanism	SERM — blocks the receptor	Blocks estrogen production
Menopausal status	Premenopausal ++ / postmenopausal OK	Postmenopausal only (or + LH-RH)
Route / dose	Oral, 20 mg/day (evening)	Oral, 1 tab/day
Duration	5-10 years	5-10 years
Introduction / radiotherapy	❌ After RT	✅ Concurrent possible
Major side effects	Hot flashes, endometrium, thromboses	Arthralgia, bone loss, lipids
Mandatory follow-up	Annual gyne · US if bleeding	DXA every 18 months · annual lipids

Source: French INCa 2025 guidelines, SénoriF 2025-2026.

Sources & references

Scientific references

This page is based on the recommendations of learned societies (French INCa 2025, SénoriF 2025-2026, ESMO, ASCO, NCCN, NICE) and on recent international literature.

SénoriF 2025-2026. French multidisciplinary breast-cancer reference — French guidelines for breast cancer management. Adjuvant hormone therapy, pages 99-107.
INCa 2025. Recommendations on adjuvant hormone therapy for breast cancer. e-cancer.fr.
Regan MM, Francis PA, Pagani O, et al. Absolute Benefit of Adjuvant Endocrine Therapies for Premenopausal Women With Hormone Receptor-Positive, HER2-Negative Early Breast Cancer: TEXT and SOFT Trials. J Clin Oncol. 2016;34(19):2221-31. PubMed 27044936.
Coombes RC, Hall E, Gibson LJ, et al. A randomized trial of Exemestane after two to three years of Tamoxifen Therapy in postmenopausal women with primary breast cancer. N Engl J Med. 2004;350(11):1081-92. PubMed 15014181.
Loibl S, André F, Bachelot T, et al. Early breast cancer: ESMO Clinical Practice Guideline for diagnosis, treatment and follow-up. Ann Oncol. 2024;35(2):159-182. PubMed 38101773.
Andre F, Ismaila N, Allison KH, et al. Biomarkers for Adjuvant Endocrine and Chemotherapy in Early-Stage Breast Cancer: ASCO Guideline Update. J Clin Oncol. 2022;40(16):1816-1837. PubMed 35439025.
Johnston SRD, Toi M, O'Shaughnessy J, et al. Abemaciclib plus endocrine therapy for hormone-dependent, HER2−, node-positive, high-risk early breast cancer (monarchE): 5-year outcomes. Lancet Oncol. 2024.
Slamon D, Lipatov O, Nowecki Z, et al. Ribociclib plus Endocrine Therapy in Early Breast Cancer. N Engl J Med. 2024;390:1080-1091.
Tutt ANJ, Garber JE, Kaufman B, et al. Adjuvant Olaparib for Patients with BRCA1- or BRCA2-Mutated Breast Cancer. N Engl J Med. 2021;384:2394-2405. PubMed 34081848.
Briot K, Tubiana-Hulin M, Bastit L, et al. Effect of a switch of aromatase inhibitors on musculoskeletal symptoms in postmenopausal women with hormone-receptor-positive breast cancer: the ATOLL study. Breast Cancer Res Treat. 2010;120(1):127-34.
Henry NL, Unger JM, Schott AF, et al. Randomized, Multicenter, Placebo-Controlled Clinical Trial of Duloxetine Versus Placebo for Aromatase Inhibitor–Associated Arthralgias in Early-Stage Breast Cancer: SWOG S1202. J Clin Oncol. 2018;36(4):326-332.
Bouvard B, Briot K, Legrand E, et al. French Society of Rheumatology recommendations on prevention and treatment of aromatase inhibitor-induced osteoporosis. Joint Bone Spine. 2019.

Article written and medically reviewed by Dr Jérémie Zeitoun, gynecological surgeon in Paris, former praticien spécialiste at Institut Gustave Roussy. Last updated: May 10, 2026.

This article is provided for information only and does not replace an individual medical consultation. Hormone therapy prescription and follow-up are carried out by your referring medical oncologist.

FREQUENTLY ASKED QUESTIONS

Frequently asked questions

Is hormone therapy a form of chemotherapy?

No. Hormone therapy is a targeted treatment that blocks the action of hormones on tumor cells. No hair loss, no massive nausea, no IV infusions. These are tablets (or monthly injections), taken at home.

What percentage of breast cancers are hormone-dependent?

About 80% of breast cancers express hormone receptors (positive hormone receptors) and are therefore eligible for hormone therapy. It is the most common profile.

When to start treatment relative to surgery?

Tamoxifen is started after radiotherapy is completed. Aromatase inhibitors and LH-RH agonists can be started concurrently with radiotherapy. All generally begin within the 2-3 months following surgery.

What are the most common side effects?

For all molecules: hot flashes, vulvovaginal dryness. For aromatase inhibitors: joint pain (arthralgia) in 20-50% of patients, bone loss. For tamoxifen: endometrial risk (polyps, exceptionally cancer) and thromboembolic risk. All are manageable — see the dedicated section.

Can I have children after or during hormone therapy?

Not during treatment (teratogenic effect of tamoxifen, aromatase inhibitors incompatible with pregnancy). A therapeutic break can be discussed after 2 years of tamoxifen (POSITIVE trial), with mandatory non-hormonal contraception during the washout period (9 months for tamoxifen). An oncofertility consultation before starting is recommended.

What combinations are possible?

Depending on the profile: CDK4/6 inhibitors (abemaciclib MonarchE 2 years, ribociclib NATALEE 3 years), PARP inhibitors (olaparib OlympiA 12 months) in BRCA-mutated patients, ovarian suppression (LH-RH) in premenopausal women. See the combinations section.

Hormone therapy for breast cancer Dr Jérémie Zeitoun · Surgeon · Paris 8e

Key points in 30 seconds

Key figures — Hormone therapy

Talk to a specialist about your treatment

Hormone therapy in breast cancer

Four families of medications

Tamoxifen

Aromatase inhibitors

LH-RH agonists

Targeted combinations

By profile

Understanding your pathology report

Premenopausal patient

Annual pelvic ultrasound

Postmenopausal patient

Perimenopausal patient

Extension to 7-10 years

Elderly patient

Male breast cancer

What it actually looks like

Tamoxifen (Nolvadex®)

Aromatase inhibitors (anastrozole, letrozole, exemestane)

LH-RH agonists

Targeted combinations

Understanding and managing side effects

Joint pain

Hot flashes

Vulvovaginal dryness

Bone loss

Endometrial risk

Thromboembolic risk

How to manage side effects

Adapted physical activity

Switching medication or therapeutic pause

Targeted symptomatic treatments

Psychological support & sex therapist

Supportive care across the board

Keep a symptom journal.

Difficult side effects? Any questions?

Your pathway, step by step

Breast MDT meeting

Baseline workup

Prescribing consultation

Starting treatment

Regular monitoring

Reassessment at 5 years

Useful documents

Reading a pathology report

Hormone therapy booklet — Institut Curie

BRCA hereditary risk — questionnaire

NCI — Breast cancer treatment (PDQ®)

Frequently asked questions about hormone therapy

Transparency on fees

Comparison: tamoxifen vs aromatase inhibitors

Discuss your situation

Scientific references

Frequently asked questions

Is hormone therapy a form of chemotherapy?

What percentage of breast cancers are hormone-dependent?

When to start treatment relative to surgery?

What are the most common side effects?

Can I have children after or during hormone therapy?

What combinations are possible?