Breast cancer

Treatment of localized breast cancer

The treatment of patients with localized breast cancer typically involves surgery and is often complemented by additional systemic therapies such as chemotherapy, endocrine therapy, immunotherapy, targeted therapies, in addition to radiotherapy.

Breast cancer surgery and reconstruction

Surgery is the cornerstone in the treatment of localized breast cancer, and it is rare for it not to be recommended. It is tailored to the patient's preferences and performed by breast surgeons who are often specialized in oncological plastic surgery. The surgery department at Gustave Roussy specializes in outpatient surgery for breast cancer, oncoplastic techniques involving breast reshaping during lumpectomies, and immediate breast reconstruction performed during the same procedure as the mastectomy (offered whenever possible unless contraindicated). Gustave Roussy provides all innovative breast reconstruction techniques: using the patient's own tissues, such as fat injections (lipofilling), breast reconstruction through microsurgery (free flaps of DIEP, PAP, gracilis, lumbar, fascia lata, etc.), or pedicled flaps (latissimus dorsi with a short scar and without implants, etc.). Our team also addresses the aftereffects of cancer treatments such as breast deformation after lumpectomy.

► Learn more about breast cancer surgery and reconstruction

Chemotherapy

The efficacy of adjuvant chemotherapy in reducing the risk of breast cancer recurrence has been well established, with studies showing reductions ranging from 5% to over 50%. Its primary objective is to eradicate any residual tumor cells that may not be detectable. In certain cases, chemotherapy may be administered before surgery to quickly control the disease, increase the chances of breast preservation, or facilitate breast cancer surgeries that were initially deemed complex. It is important to note that if chemotherapy is administered intravenously, the placement of a portacath – a small device implanted under the skin and connected to a catheter – is necessary throughout the treatment period.

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Endocrine therapy

Endocrine therapy works by blocking hormone secretions or inhibiting their action to impede the proliferation of cancer cells. It is recommended for patients with breast cancer that expresses hormone receptors (estrogen and/or progesterone), with an expected benefit in reducing the risk of recurrence. This is often the case as these treatments decrease the risk of recurrence, including metastases, local recurrence, or relapse, by 30 to 60%.

Several treatments are available:

• The anti-estrogen treatment Tamoxifen blocks the functioning of the estrogen receptor on tumor cells that may remain in the body or have the potential to develop. Thus, it can prevent both a recurrence of the treated cancer (local or metastatic) and the onset of new breast cancer.
• The aromatase inhibitors (Letrozole, Anastrazole, Exemestane) are traditionally prescribed for postmenopausal women. They block the activity of an enzyme capable of producing estrogen hormones after menopause when the ovaries no longer function. Their efficacy is well established in reducing the risk of recurrence and preventing new breast cancer.
• Ovarian suppression can be used in premenopausal women to induce artificial menopause, in addition to Tamoxifen or Aromatase Inhibitors. These treatments are administered in the form of a subcutaneous or intramuscular injection once a month or every three months (Enantone®, Decapeptyl®, Zoladex®). Their side effects include menopausal symptoms such as hot flashes, vaginal dryness, and weight gain.

► Learn more about the adverse events of endocrine therapy

Targeted therapies

Targeted therapies are medications designed to selectively target specific pathways or receptors within cancer cells.

Several targeted therapies are available for HER2-positive breast cancers. Trastuzumab, an antibody targeting HER2, is associated with a 50% reduction in the risk of recurrence, in addition to that conferred by chemotherapy and other treatments. Trastuzumab will be prescribed for patients with invasive breast cancer strongly expressing the HER2 protein on the surface of tumor cells when chemotherapy is indicated. Pertuzumab another therapy targeting HER2, will be prescribed in combination with Trastuzumab and chemotherapy, before surgery in patients with breast cancer and lymph node involvement. Trastuzumab emtansine or T-DM1, an antibody-drug conjugate targeting HER2, will be prescribed after initial chemotherapy followed by surgery in the absence of complete sterilization of the tumor bed.

In patients with hormone receptor-positive breast cancer at increased risk of relapse, abemaciclib a cell cycle inhibitor, is associated with a reduction in the risk of recurrence by approximately 6.4% at 4 years. Abemaciclib will be prescribed for patients with invasive breast cancer presenting with 4 or more lymph node involvement or 1 to 3 lymph nodes with a grade III or a tumor size of 5 cm or more. Olaparib, an inhibitor of a DNA repair enzyme, is associated with a reduction in the risk of recurrence by approximately 7.3% at 4 years. It will be prescribed for patients with a mutation in the BRCA1/2 gene and an involvement of at least 4 lymph nodes or a non-complete response to neoadjuvant chemotherapy according to the CPS EG criterion. Olaparib is also prescribed for patients with triple-negative breast cancer in case of a non-complete response to neoadjuvant chemotherapy or if the tumor is larger than 2 cm or there is lymph node involvement without prior neoadjuvant chemotherapy.

Radiotherapy

Radiotherapy is a key step in the management of the majority of patients with breast cancer. It uses ionizing radiation (photons and/or electrons) which primarily acts by breaking the DNA strands within the nucleus, thus preventing cell multiplication. Radiotherapy is indicated after surgery to reduce the risk of local and/or regional recurrence of breast cancer.

Adjuvant radiotherapy is generally prescribed at a frequency of 5 sessions per week for a duration of 3 to 5 weeks depending on the required dose for each patient. The breast pathology committee has been a pioneer in the development of hypofractionated radiotherapy. This treatment approach is shorter in duration and more intense, reducing the total number of sessions, easing the burden of treatment, and preserving healthy tissues while maintaining the same effectiveness. Thus, we have implemented a 5-day radiotherapy program specifically for women aged 50 and older who have undergone breast-conserving surgery for localized breast cancer without lymph node involvement. This program allows for the radiotherapy sessions to be completed over five consecutive days, from Monday to Friday, with each session lasting approximately 15 minutes. Treatment is administered after ensuring precise positioning by radiation therapists and using onboard imaging, without requiring hospitalization.

Such organization is possible through advanced radiotherapy techniques, including:

• A positioning scanner that delineates the irradiation area and protects organs.
• Synchronization with breathing to better shield the heart and lungs.
• Automated contouring using artificial intelligence techniques.
• Intensity-modulated script-based dosimetry developed by our medical physicists.
• Highly precise and personalized radiotherapy guided by imaging.

► Learn more about radiotherapy in breast cancer

Treatment of metastatic breast cancer

Distant metastases refer to the spread of tumor cells originating from breast cancer to organs other than the breast and its adjacent lymph nodes. Patients with metastases are typically treated with systemic therapies; however, outside of exceptional cases, a definitive cure cannot be achieved. A metastatic cancer is considered a chronic condition requiring long-term treatment. Regular follow-up consultations and imaging are performed to assess the efficacy and tolerance of the prescribed treatments.

The treatment options for patients with breast cancer are numerous and tailored to each individual. They include chemotherapy, endocrine therapy in patients with breast cancer expressing hormone-receptors, targeted therapy (monoclonal antibodies and conjugates, cell cycle inhibitors, DNA repair enzyme inhibitors), radiotherapy targeted to a specific lesion, surgery in certain cases, and denosumab in patients with bone metastases. Our doctors may also offer a clinical trial as a treatment option.

Ongoing research and clinical trials

Gustave Roussy is a cancer center for patient care and research. In many instances, alternative techniques or treatments are developed, studied, and may be offered to our patients with the aim of enhancing current standards. These studies cover screening, diagnosis, prevention, surgery, radiotherapy, medical treatments, as well as supportive care. They are always optional, proposed, discussed, and carried out only where patients could potentially benefit and wish to participate in ongoing research.

► Learn more about the ongoing clinical trials

Localised breast cancer

Research programs focusing on early preoperative breast cancer aim to enhance available therapeutic strategies and improve breast cancer cure rates. These programs are designed to deepen our understanding of the mechanisms of action of different treatment classes (e.g., immunotherapies, targeted therapies) and to identify effective treatment combinations. By focusing on the preoperative context, our goal is to optimize treatment protocols and outcomes for breast cancer patients through targeted research and innovative approaches. Below are some ongoing studies for early breast cancer:

POP-DURVA clinical trial (NCT05215106 ; https://classic.clinicaltrials.gov/ct2/show/NCT05215106)

BIS-PROGRAM clinical trial (NCT05180006 ; https://clinicaltrials.gov/study/NCT05180006)

Metastatic breast cancer

Our research programs on metastatic breast cancer aim to optimize treatment strategies through four fundamental axes:

• Academic Research Programs in the field of Antibody-Drug Conjugates (ADCs). This program allows patients to benefit from early access to innovative and promising treatments. Concurrently, we examine various biological characteristics such as gut microbiota, immune system specificities, genetic profiles, and tumor properties. We analyze how these elements evolve during treatment to better understand the mechanisms underlying the efficacy or resistance to therapies. This comprehensive approach helps decipher the complexities of carcinogenesis, paving the way for significant improvements in ADC treatment effectiveness.
• Academic Research Programs in close collaboration with cooperative research groups (e.g., UNICANCER, SOLTI) as part of various national and European studies.
• Participation in Industry-Sponsored Clinical Trials. We actively engage in industry-sponsored clinical trials, providing early access to innovative therapies.
• Médecine de Précision. Within various research projects at Gustave Roussy, we systematically sequence blood and, in some cases, tumors to identify molecular alterations that could enable patient inclusion in clinical trials dedicated to targeted treatments. Our goal is to tailor therapies to the individual genetic characteristics of tumors to optimize treatment effectiveness.

► Learn more about the ongoing clinical trials at Gustave Roussy and eligibility criteria

Treatment guidelines for professionals

Please refer to Référentiel francilien de pathologie mammaire (Sénorif) / Attitudes diagnostiques et thérapeutiques, protocoles de traitement 2021-2022