Breast cancer treatments vary according to whether the cancer is invasive or non-invasive, whether it has metastasized or not, and the nature of the cancer cells. In particular, treatment will depend on the presence or absence of hormone receptors (estrogen receptors and/or progesterone receptors) and the presence or absence of the HER2 receptor on the surface of tumor cells. Treatments will use one or, more often, several of the five weapons available to oncologists to treat cancer. Surgery and/or radiotherapy which are localized treatments; chemotherapy, targeted therapies and/or immunotherapy, which are treatments that spread throughout the body. Chemotherapy or targeted therapy directly kills cancer cells that could have left the breast to invade lymph nodes or form distant metastases. Immunotherapy directly kills these tumor cells by stimulating the immune system which can then eliminate them. Due to the multiple possible treatments, the care of a patient is carried out by a multidisciplinary team composed of surgical oncologist, plastic surgeon, radiotherapist, oncologist, pathologist. This team meets at a multidisciplinary meeting to decide on the best treatment for each of their patients.
Surgery has been an essential treatment for breast cancer since it was first described in 1894 by William Halstead. Since then, surgical procedures have greatly improved. They are increasingly limited in order to preserve as much tissue as possible without any subsequent risk to the patient. Two types of surgery are performed: lumpectomy or mastectomy.
A lumpectomy involves removing the tumor. A particular lymph node, the “sentinel” lymph node is also taken. This is the first lymph node likely to be invaded by tumor cells. Microscopic examination of the tumor and sentinel lymph node will reveal whether cancer cells have migrated from the tumor to the lymph node.
A mastectomy involves removing the breast where the tumor is present. The sentinel lymph node will be removed. If lymph nodes were palpable, they will also be removed. Breast reconstruction may be performed immediately or during a second operation. Reconstructive techniques are important for optimizing aesthetic results and, consequently, the patient’s quality of life, body image and self-esteem.
Surgical treatment may be supplemented by local radiotherapy. This uses radiation to kill cancer cells locally. Radiotherapy may be performed on the breast and/or on nearby lymph nodes.
Since hormone receptors are present on the tumor cells of nearly three-quarters of breast cancers, patients with this type of cancer will be treated with hormone therapy. These treatments target hormone receptors and can therefore be considered targeted therapy. By blocking the action of hormones, estrogen or progesterone, hormone therapy prevents these hormones from stimulating the multiplication of tumor cells. For women treated with hormonal therapy, this treatment is done for 5 to 10 years. The duration will depend on the type of hormone therapy used and the stage of the disease, which may have been discovered at an early or later stage.
For patients whose tumor cells don’t express hormone receptors but do express the HER2 receptor, a targeted therapy specifically targeting this receptor will be performed.
Chemotherapy that blocks rapidly multiplying cells such as cancer cells can be used alone or in combination with other treatments. This is the case, for example, of patients with invaded lymph nodes, metastases or aggressive cancer such as triple-negative breast cancer (see above). This chemotherapy can be given before surgery to reduce the size of the tumor (so-called “neoadjuvant” treatment). It can also be carried out after surgery to prevent recurrence or to treat metastases (so-called “adjuvant” treatment).
The fifth weapon against cancer, immunotherapy is now used as neoadjuvant and adjuvant therapy to treat triple negative breast cancers. Immunotherapy stimulates the immune system to eliminate tumor cells.
New advances are being made ever more rapidly to optimize the management of breast cancer patients. These advances include, for example, new tests to better distinguish between patients who should or should not be treated with chemotherapy. New targeted therapies have been developed for patients with HER2-expressing or triple-negative cancer. Recently, a new drug with an original mechanism has been available for patients with a BRCA gene mutation. These advances lead to treatments that are increasingly better suited to each patient.
