How long does breast radiotherapy take?

Total treatment duration is generally 3 to 5 weeks, with 5 sessions per week. The most common schedule in France is moderately hypofractionated radiotherapy: 40.05 Gy in 15 sessions of 2.67 Gy, over 3 weeks. The conventional schedule (50 Gy in 25 sessions over 5 weeks) is still used in some situations. For eligible patients, the ultra-hypofractionated FAST-Forward schedule offers 26 Gy in 5 sessions over a single week. A boost (additional dose to the tumour bed) may add a few extra sessions for patients under 50 or with risk factors.

What is partial breast irradiation?

Partial breast irradiation (PBI) treats only the area around the lumpectomy scar, rather than the whole breast. It is reserved for patients at low risk of recurrence: age over 50, pT1N0 tumour, grade I-II, hormone receptor positive, no lymphovascular invasion, clear margins. The IMPORT Low trial (Lancet Oncol 2017) and GEC-ESTRO trial (Lancet Oncol 2016) have demonstrated its effectiveness. PBI can be delivered by external beam radiotherapy or interstitial brachytherapy.

What are the side effects of breast radiotherapy?

Acute effects (during and just after treatment): skin redness (radiodermatitis), fatigue, sometimes underarm discomfort. Late effects (months to years afterwards): change in breast texture, telangiectasias (small visible dilated vessels), occasional moderate hardening, rare fibrosis. Modern techniques (3D-conformal, IMRT, breath hold DIBH) have considerably reduced cardiac and pulmonary toxicity. Mean cardiac dose should stay below 3 Gy for breast-only irradiation (RECORAD 2025 guideline).

Can radiotherapy be combined with breast reconstruction?

Yes, but it requires planning ahead with your breast surgeon and the radiation oncologist. Radiotherapy after implant-based reconstruction increases the risk of capsular contracture and may affect the aesthetic outcome. For autologous reconstructions (DIEP, latissimus dorsi flap), the impact is smaller. If radiotherapy is anticipated, a delayed reconstruction or a two-stage protocol (tissue expander followed by definitive implant after radiotherapy completion) is often preferred.

Is radiotherapy painful?

The radiotherapy sessions themselves are entirely painless. You feel nothing during the irradiation, just as with an X-ray. Each session lasts 10 to 15 minutes (with only a few minutes of actual beam time). Skin redness may appear from the third week and can be uncomfortable — your radiation oncologist will prescribe suitable creams. Cumulative fatigue is the most common effect.

Why do they tattoo my skin before radiotherapy?

To position your body in exactly the same way at every session, the radiation oncologist makes a few small skin tattoos (about the size of a pinhead, in black or blue ink). These marks are permanent but discreet. Some centres now use surface-guided positioning systems (without tattoos). This millimetre-level precision is essential to spare the healthy tissues around the breast.

What is deep inspiration breath hold (DIBH) in left-sided breast radiotherapy?

DIBH (Deep Inspiration Breath Hold) means delivering radiotherapy while the patient holds a deep breath. The lung inflates and moves the heart away from the left breast, considerably reducing the cardiac dose. DIBH is now the standard of care for left-sided breast cancers in France. Sessions take slightly longer because they are delivered in several 15-20 second breath holds guided by an optical system.

Breast cancer radiotherapy Paris — Dr Jérémie Zeitoun

Q: Why is radiotherapy needed after a lumpectomy?

After breast-conserving surgery (lumpectomy), radiotherapy is offered to almost all patients. It destroys any microscopic tumour cells that may remain in the breast and reduces the risk of local recurrence by about 50 % at 15 years (EBCTCG meta-analysis, Lancet 2011). The combination of lumpectomy plus radiotherapy gives a survival rate equivalent to mastectomy for early-stage cancers.

KEY POINTS

Key points in 30 seconds

What is it? High-energy X-rays targeted at the operated breast to destroy any microscopic tumour cells that may remain.
Who needs it? Near-systematic after lumpectomy. Sometimes required after mastectomy (large tumour, involved nodes, young age).
How long? The full treatment usually lasts 3 to 5 weeks, depending on the chosen schedule. For eligible patients: only 1 week (5 sessions, FAST-Forward schedule).
Painless during sessions. Skin reactions possible (redness, tenderness) from the 3^rd week onwards.
Benefit: reduces local recurrence by about 50 % at 15 years (EBCTCG meta-analysis, Lancet 2011) — this is what makes breast-conserving surgery possible.

KEY FIGURES

Key figures — Breast radiotherapy

Medical statistics to understand the role and effectiveness of radiotherapy at a glance.

> 99 %

of lumpectomies are followed by radiotherapy

50 %

reduction in local recurrence at 15 years (EBCTCG)

40 Gy

standard dose in 15 sessions (moderately hypofractionated)

26 Gy

ultra-hypofractionated dose in 5 sessions (FAST-Forward)

3-5 wks

typical duration of a full treatment

10-15 min

session duration (including 2-5 min of beam time)

< 3 Gy

maximum mean cardiac dose (RECORAD 2025)

100 %

painless during the session

4-6 wks

recommended interval between surgery and start of radiotherapy

3

main modern schedules: moderately hypofractionated · ultra-hypofractionated · partial

2011

landmark EBCTCG meta-analysis (Lancet)

100 %

covered by French national health insurance (ALD 30)

Section 01 · Overview

What is radiotherapy?

Highly precise X-rays to complete what surgery began.

Radiotherapy uses high-energy X-rays — far more powerful than those of a mammogram or CT scan — to destroy any microscopic tumour cells that may have remained in the breast after surgery. You see nothing, you feel nothing during the session. But these rays, calculated to the millimetre, do an essential job: securing the result of the operation.

Why is it needed? Because a lumpectomy removes the visible tumour, but microscopic cells can remain scattered through the surrounding breast tissue. Without radiotherapy, the risk of local recurrence would be much higher. The combination of breast-conserving surgery + radiotherapy achieves survival equivalent to mastectomy for early-stage cancers (Veronesi 1973, Fisher NSABP B-06, EBCTCG 2011).

Techniques have evolved enormously over the past 15 years. Treatment today is shorter, more precise, and has far fewer side effects than 20 years ago. The START B, FAST-Forward, IMPORT Low and HypoG-01 trials have shifted practice towards hypofractionation (fewer sessions, higher dose per session, equivalent or improved efficacy, often less toxicity).

Why

Destroy any remaining cells

After a lumpectomy, microscopic cells can remain scattered through the breast. Radiotherapy destroys them while sparing the surrounding healthy tissue.

How

X-rays targeted to the millimetre

A linear accelerator delivers high-energy photons from several angles. A prior planning CT scan calculates the ideal trajectory, session by session.

Who

A radiation oncologist

A specialist doctor prescribes the schedule, contours the target volume on the images, validates the dosimetry and follows you during and after treatment.

Breast cancer radiotherapy machine — treatment room with carer and patient — A modern radiotherapy treatment room: millimetre-level precision, dedicated team, controlled environment.

Section 02 · When it's used

When is radiotherapy needed?

Radiotherapy is not always required. It is discussed case by case at the MDT.

The decision depends on several factors: the type of surgery performed (lumpectomy or mastectomy), the size and extent of the tumour, the nodal status (how many nodes are involved), the biological profile (grade, hormone receptors, HER2), your age and the surgical margins obtained.

The decision is always made at a Multidisciplinary Tumour Board (MDT), where your case is reviewed jointly by surgeons, medical oncologists, radiation oncologists and pathologists. Here are the three main scenarios.

Scenario 1

After lumpectomy

Near-systematic. When the tumour is removed while preserving the breast, radiotherapy completes the procedure by treating the whole breast. An additional targeted dose (the boost) is added on the operated area if you are under 50 or if certain pathology features suggest a higher recurrence risk.

SENORIF 2025-2026 · EBCTCG 2011

Scenario 2

After mastectomy

More selective. Radiotherapy is not always needed after mastectomy. It is recommended if the tumour was large, if surgical margins were not clear enough, if nodes were involved, or if several risk factors are present. The chest wall is then irradiated. This also affects reconstruction options.

SENORIF 2025-2026

Scenario 3

The axillary nodes

Depending on pathology findings. If the sentinel lymph node or axillary dissection shows nodal involvement, targeted radiotherapy of the lymphatic drainage areas may be offered. It is the logical extension of axillary surgery in selected cases.

SENORIF 2025-2026

When is radiotherapy not indicated?

After a mastectomy for a small tumour with no nodal involvement and no specific risk factor.
For a pure low-grade in situ (non-invasive) cancer treated by total mastectomy.
If you have already received breast radiotherapy in the past (except for a re-irradiation protocol discussed at the MDT).
Absolute contraindications: ongoing pregnancy, certain connective tissue diseases (such as active scleroderma).

The final decision is always shared and validated at the Multidisciplinary Tumour Board (MDT).

Section 03 · Techniques

Tailored radiotherapy

Shorter. More precise. Better tolerated.

Today's radiotherapy is no longer that of twenty years ago. European and British clinical trials from 2010-2020 have profoundly transformed practice. We now deliver a higher dose per session over fewer total sessions. The result: a shorter, equally effective, and often better tolerated treatment.

Here are the three main modern schedules, and the technologies that make them possible.

Current standard

The 3-week schedule

15 sessions spread over 3 weeks. This is now the most widely used schedule in France. As effective as the older 5 to 6 week schedules, and often better tolerated by the skin.

Essai HypoG-01 · START B

The shortest Innovation

The 1-week express schedule

Only 5 sessions over 1 week. Available in selected situations (no nodal irradiation, no boost required). 5-year data show equivalent efficacy and tolerance compared with the standard schedule. Useful for patients living far away or with active lifestyles.

Essai FAST-Forward · Lancet 2020

Selective Low risk

Partial breast irradiation

Rather than irradiating the whole breast, only the area around the scar is targeted. This option is reserved for patients at low risk of recurrence (small, slow-growing cancer with no aggressive features). It reduces fatigue and skin reactions.

IMPORT Low 2017 · GEC-ESTRO 2016

Add-on

The boost (targeted dose)

A few additional sessions focused on the exact area where the tumour was. Offered if you are under 50, or if certain factors make recurrence more likely. It is an extra local "safety net", often integrated directly into the main schedule.

EORTC 22881 · RTOG 1005

Cardiac sparing

Breath hold (DIBH)

For left-sided breast cancers, you are asked to take a deep breath and hold it for a few seconds during irradiation. The lung inflates and moves the heart away from the beam path. Result: the dose received by the heart drops sharply. This has now become the standard of care.

DIBH · Deep Inspiration Breath Hold

Millimetre precision

Sculpted radiotherapy

Modern machines adjust the beam intensity to match the exact shape of the target volume. The dose hugs the breast contours and spares the surrounding organs (heart, lung, contralateral breast) as much as possible. Particularly useful when the anatomy is complex or when the lymph nodes also need to be treated.

SENORIF 2025-2026 · RECORAD 2025

Breast radiotherapy dosimetry — control screens, hypofractionation and DIBH planning — Control room: dosimetry is computed on a workstation to spare the surrounding organs (heart, lung, contralateral breast).

Section 04 · Your pathway

Your pathway, step by step

From the first radiotherapy consultation to your last annual review, here is how your care unfolds in practice. At every step, you know what to expect.

1

Consultation with the radiation oncologist

Usually 4 to 6 weeks after surgery, once healing is complete. The radiation oncologist reviews your full file (surgery, pathology, MDT decision), examines your breast, and explains the proposed schedule, duration and expected effects. All your questions are answered. You sign the informed consent form.
2

Planning CT scan (simulation)

A specific CT scan in the treatment position, with the arms above the head. It takes about 20 minutes. For left-sided breasts, the breath-hold technique is also checked. At the end, a few small skin tattoo marks (about the size of a pinhead, in black ink) or surface-guided landmarks allow you to be repositioned identically at every session.
3

Dosimetric planning

Without you present. Over 1 to 2 weeks, the radiation oncologist, medical physicist and dosimetrist design your treatment plan on a workstation. They contour the target volumes (breast, tumour bed, nodal areas if required) and the organs to protect (heart, lung, contralateral breast). They calculate the angles, energies and precise doses.
4

The treatment sessions

You attend 5 days a week (Monday to Friday) at a fixed time. You lie on the treatment table in the same position as at the planning CT. The machine rotates around you without touching. The actual beam time only lasts a few minutes per session. You leave straight after — no hospital stay required. A weekly consultation with the radiation oncologist monitors your tolerance.
5

End-of-treatment consultation

After your final session, you see the radiation oncologist for a review: tolerance, ongoing skin care, next steps (often endocrine therapy if HR+). A detailed report is sent to your breast surgeon, your medical oncologist and your GP.
6

Long-term follow-up

Review at 3 months with the radiation oncologist, then at 6 months, 1 year, and annually thereafter. Follow-up is then shared with your breast surgeon and medical oncologist (annual mammogram, clinical examination every 6 months). Residual skin changes (mild telangiectasias, texture changes) are normal and remain stable over time.

Section 05 · Side effects

What you may experience

Not every patient reacts the same way. Some go through radiotherapy without significant discomfort. Others feel marked fatigue and a moderate skin reaction. Modern techniques have considerably reduced toxicity compared with radiotherapy 20 years ago, but a few effects remain common.

Acute — common

Skin redness (radiodermatitis)

Appears from the 3^rd week. Redness, sometimes a sensation of warmth, similar to mild to moderate sunburn. Skin peeling is less common. A suitable cream (often calendula-based or a prescribed emollient) is usually enough. The skin recovers within 2 to 4 weeks after treatment ends.

Acute — common

Fatigue

The most frequently reported effect. Often cumulative: barely noticeable at first, more marked towards the end of treatment. It fades over 4 to 6 weeks after the last session. It is important to keep up gentle physical activity (walking, yoga), which aids recovery.

Acute — sometimes

Underarm discomfort

If you have had a sentinel lymph node biopsy or axillary dissection, irradiation of the nodal areas may cause tenderness or mild temporary swelling. Physiotherapy started early after surgery helps enormously.

Late — moderate

Change in breast texture

A few months after treatment ends, the breast may feel slightly firmer, less supple than before. This change develops gradually and then stays stable. It is rarely bothersome but may be visible in some patients.

Late — moderate

Telangiectasias

Small visible dilated vessels on the skin, often near the scar. They appear 1 to 2 years after treatment. Painless. They can be reduced with dermatological laser treatment if cosmetically desired.

Late — rare

Breast fibrosis

More pronounced hardening of the breast with moderate retraction. Now rare with modern techniques (hypofractionation, IMRT). Patients with thin skin or who received concomitant chemotherapy are slightly more at risk.

What about the surrounding organs?

The heart — For left-sided breasts, the breath-hold technique (DIBH) moves the heart away from the beam path. The target mean cardiac dose is < 3 Gy for breast-only irradiation, and < 5 Gy when nodal areas are also treated (RECORAD 2025 guideline). Long-term cardiac risk has become very low with these modern techniques.

The lung — A small area of the upper ipsilateral lung may receive a dose. Radiation pneumonitis is rare (< 2 %) and usually resolves on its own.

The contralateral breast — Receives very little dose thanks to intensity-modulated techniques. Particular vigilance is needed for young patients or those carrying a BRCA mutation.

Breast radiotherapy tolerance — patient support and monitoring during treatment — Personalised support throughout treatment: weekly consultations, skin monitoring, side effect management.

COMPARISON

Moderately hypofractionated vs ultra-hypofractionated

The two main modern schedules for radiotherapy after breast-conserving surgery. The choice depends on your profile and whether a boost or nodal irradiation is required.

Criterion	Moderately hypofractionated	Ultra-hypofractionated (FAST-Forward)
Total dose	40,05 Gy	26 Gy
Number of sessions	15	5
Dose per session	2,67 Gy	5,2 Gy
Total duration	3 weeks	1 week
Boost compatible	Yes (sequential or integrated)	Not recommended in routine
Nodal irradiation compatible	Yes	Not in routine
Evidence level	Very high (START B, HypoG-01)	High (FAST-Forward, 5-year follow-up)
Status in France	Reference standard	Growing option, selective

Section 06 · Resources

Find out more

Official sources and professional guidelines you can consult directly.

Guideline

HAS — French guidelines

Haute Autorité de Santé (French national health authority). National guidelines on breast cancer management, including the role of radiotherapy.

INCa — French National Cancer Institute

Patient guides, national statistics, recommended care pathways. A trusted reference source for reliable information.

SFRO — French Society of Radiation Oncology

Société Française de Radiothérapie Oncologique. RECORAD guidelines regularly updated, latest practice consensus 2025.

Landmark trials and meta-analyses

EBCTCG. Effect of radiotherapy after breast-conserving surgery on 10-year recurrence and 15-year breast cancer death: meta-analysis of individual patient data for 10,801 women in 17 randomised trials. Lancet. 2011;378(9804):1707-1716. PubMed 22019144.
Murray Brunt A, Haviland JS, Wheatley DA, et al. Hypofractionated breast radiotherapy for 1 week versus 3 weeks (FAST-Forward): 5-year efficacy and late normal tissue effects results from a multicentre, non-inferiority, randomised, phase 3 trial. Lancet. 2020;395(10237):1613-1626. PubMed 32580883.
Haviland JS, Owen JR, Dewar JA, et al. The UK Standardisation of Breast Radiotherapy (START) trials of radiotherapy hypofractionation for treatment of early breast cancer: 10-year follow-up results of two randomised controlled trials. Lancet Oncol. 2013;14(11):1086-1094. PubMed 24055415.
Coles CE, Griffin CL, Kirby AM, et al. Partial-breast radiotherapy after breast conservation surgery for patients with early breast cancer (UK IMPORT LOW trial): 5-year results from a multicentre, randomised, controlled, phase 3, non-inferiority trial. Lancet. 2017;390(10099):1048-1060. PubMed 28779963.
Strnad V, Ott OJ, Hildebrandt G, et al. 5-year results of accelerated partial breast irradiation using sole interstitial multicatheter brachytherapy versus whole-breast irradiation with boost after breast-conserving surgery for low-risk invasive and in-situ carcinoma of the female breast: a randomised, phase 3, non-inferiority trial. Lancet. 2016;387(10015):229-238. PubMed 26494415.
Bartelink H, Maingon P, Poortmans P, et al. Whole-breast irradiation with or without a boost for patients treated with breast-conserving surgery for early breast cancer: 20-year follow-up of a randomised phase 3 trial. Lancet Oncol. 2015;16(1):47-56. PubMed 25500422.
Whelan TJ, Pignol JP, Levine MN, et al. Long-term results of hypofractionated radiation therapy for breast cancer. N Engl J Med. 2010;362(6):513-520. PubMed 20147717.
Darby SC, Ewertz M, McGale P, et al. Risk of ischemic heart disease in women after radiotherapy for breast cancer. N Engl J Med. 2013;368(11):987-998. PubMed 23484825.
Vrieling C, van Werkhoven E, Maingon P, et al. Prognostic factors for local control in breast cancer after long-term follow-up in the EORTC boost vs no boost trial. JAMA Oncol. 2017;3(1):42-48. PubMed 27607734.
SENORIF Group. Breast cancer diagnostic and therapeutic reference — SENORIF 2025-2026. French multidisciplinary guidelines for breast cancer management.
Hickey BE, James ML, Lehman M, et al. Hypofractionated radiation therapy for early breast cancer. Cochrane Database Syst Rev. 2016;7:CD003860. PubMed 27437494.
NICE Guideline NG101. Early and locally advanced breast cancer: diagnosis and management. National Institute for Health and Care Excellence, 2018 (updated 2024).

Page written and medically reviewed by Dr Jérémie Zeitoun, breast surgical oncologist in Paris, former Specialist Practitioner at Institut Gustave Roussy. Last reviewed: 10 May 2026 · Aligned with SENORIF 2025-2026 guidelines.

This page is for information only and does not replace a consultation with a radiation oncologist.

FREQUENTLY ASKED QUESTIONS

Your questions about radiotherapy

Why is radiotherapy needed after a lumpectomy?

After breast-conserving surgery, it destroys any microscopic tumour cells that may remain in the breast. It reduces the risk of local recurrence by about 50 % at 15 years (EBCTCG meta-analysis, Lancet 2011). This is what makes breast-conserving surgery as safe as mastectomy for early-stage disease.

How long does the treatment last?

The full treatment usually lasts 3 to 5 weeks, depending on the chosen schedule: moderately hypofractionated (40.05 Gy in 15 sessions over 3 weeks, the most common), conventionally fractionated (50 Gy in 25 sessions over 5 weeks, in some situations), or ultra-hypofractionated FAST-Forward (26 Gy in 5 sessions over 1 week, for eligible patients). A boost may add a few sessions if you are under 50 or have a risk factor.

Does it hurt?

The session itself is completely painless — you feel nothing, just as with an X-ray. Skin redness (like mild sunburn) often appears from the 3^rd week and can be uncomfortable. Cumulative fatigue is the most frequent effect.

Can I keep working during radiotherapy?

Yes, many patients keep working, especially at the start of treatment. End-of-course fatigue may justify partial or full sick leave — to be discussed with your GP and your radiation oncologist. Radiotherapy is compatible with a near-normal daily life.

Is radiotherapy compatible with breast reconstruction?

Yes, but it requires planning ahead. If radiotherapy is anticipated, a two-stage protocol (temporary expander then definitive implant later) or an autologous reconstruction (DIEP, latissimus dorsi flap), which is more tolerant, is often preferred. See the Breast reconstruction page for more details.

What about the risk to the heart?

With modern techniques (breath hold DIBH for left-sided breasts, IMRT, precise dosimetric planning), the cardiac dose stays very low (target mean < 3 Gy). Long-term cardiovascular risk has become marginal compared with older techniques. Most French centres now apply these protocols.

And afterwards? What about follow-up?

Reviews at 3 months, 6 months and 1 year with the radiation oncologist. Then shared follow-up with your breast surgeon and medical oncologist: clinical examination every 6 months, annual mammogram, ultrasound as needed. Endocrine therapy will often start after radiotherapy for HR+ cancers.

How do you find a good radiotherapy centre in Paris?

I work closely with several centres in Paris and the near suburbs, equipped with the latest technologies (DIBH, VMAT, tomotherapy). During our consultation, I will refer you to the team best suited to your situation, your home location and your constraints. A second opinion is always possible and encouraged.

Radiotherapy for breast cancer Understand, anticipate, navigate calmly