Breast cancer

Dr Barbara Pistilli

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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 of localized breast cancer treatment. It is performed by breast surgeons, who often are specialized in oncological plastic surgery. Immediate breast reconstruction following surgical intervention is offered at Gustave Roussy whenever feasible, unless contraindicated.

► Learn more about breast cancer surgery and reconstruction


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.

► Learn more about chemotherapy in breast cancer

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 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. Other schedules are possible nowadays, including the option of having radiotherapy over 5 days only. Specific techniques are also offered depending on the case presentation.

► Learn more about radiotherapy in breast cancer

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

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.

Treatment guidelines for professionnals

Consult the Référentiel francilien de pathologie mammaire (Sénorif) / Attitudes diagnostiques et thérapeutiques, protocoles de traitement 2021-2022


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