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Breast cancer: definition, symptoms and treatments

Breast cancer is a disease in which cells in the breast become abnormal and multiply uncontrollably to form a tumour. (1)

What is breast cancer?

Breast cancer is a disease in which cells in the breast become abnormal and multiply uncontrollably to form a tumour(1).

Breast cancer is the most common cancer in women worldwide, although it rarely affects men. The median age of diagnosis is 61(2,3).

It accounts for 33% of all new cases of cancer in women. Taking all sexes together, it is the second most common cancer. Incidence is rising slightly each year, but mortality is falling, although it remains the leading cause of cancer death in women(2,3).

What are the risk factors for breast cancer?

The causes and risk factors for breast cancer include genetic, hormonal and lifestyle factors.

Age, history and lifestyle factors
The risk factors for breast cancer include age, as half of all breast cancers occur between the ages of 45 and 65(3).
Modifiable behaviours such as physical inactivity, excessive alcohol consumption, smoking and being overweight increase the risk of breast cancer(4).
Family history, personal history of breast cancer or thoracic radiotherapy are also risk factors(3).

Hormonal factors
Prolonged exposure to hormones, whether as a result of early puberty, late menopause, late first pregnancy, lack of breastfeeding, or prolonged use of hormonal therapies such as the oestroprogestogenic pill, increases the risk of breast cancer(3,5).

Genetic factors
Some people carry constitutional mutations, i.e. mutations that are present in every cell of their body and are inherited. These mutations predispose them to breast and ovarian cancer. The 2 main genes involved are BRCA1 and BRCA2. Women with these mutations have a significantly higher risk of developing breast cancer during their lifetime(3,6).

Signs and symptoms of breast cance

The signs and symptoms of breast cancer include various changes in breast tissue(3).

Palpable lump or nodule
The appearance of a hard, irregular and often painless lump in the breast or under the arm in the armpit is the most common symptom. However, some lumps may be painful(3,7).

Skin changes
Changes in the skin of the breast, such as redness, oedema or warmth, may indicate inflammation. Thickening of the skin or dimpling (orange peel appearance) may also be observed(3,8). 

Nipple changes
Inversion or retraction of the nipple, as well as unusual nipple discharge and other changes in appearance may be symptoms(3,7).

Breast pain or tenderness
Swelling discovered by the patient or on clinical examination, breast pain. Although less common, pain or tenderness in a localised area of the breast can be a sign of cancer, although many women with breast cancer do not feel any pain(3).

Changes in breast size or shape
Sudden enlargement or asymmetry between the breasts may also indicate an underlying problem(3,7).

Breast cancer screening

Breast cancer screening can be carried out by self-examination, an annual clinical breast examination and mammography.

Breast cancer screening is mainly based on mammography, which is the most widely used tool for early detection of breast cancer. It can even be carried out on women with no clinical signs and no particular risk of developing breast cancer(3).

For high-risk women, a clinical examination combined with mammography, ultrasound and annual breast MRI from the age of 30 are suggested(3).

Mammography can reduce breast cancer mortality by identifying tumours at earlier stages, enabling less aggressive treatment(9).

On clinical examination, a physical examination is carried out to identify any clinical signs of breast cancer. This is followed by palpation to look for a lump, and a search for adenopathy (swollen lymph nodes)(3).

How is breast cancer diagnosed?

Breast cancer is generally diagnosed in two different contexts: following screening mammography or following the presence of clinical signs.

Clinical signs may appear in the breast or, more rarely, in lymph nodes or metastases.

A positive diagnosis is made following a biopsy. Mammography cannot be used to make a diagnosis, but it can be used to carry out other tests if the images are suspicious. In the event of any clinical or radiological abnormality, a sample is taken (biopsy).

The biopsy is analysed to confirm the diagnosis and to determine the risk of the disease evolving.

Once the diagnosis has been made, doctors are able to tell what type of cancer it is, whether it is localised or metastatic, whether it is hormone-sensitive, and what the prognostic factors are for assessing the likely course of the cancer.

What are the different types of cancer?

The most common type of cancer is invasive ductal carcinoma (or non-specific invasive carcinoma) in 75-80% of cases. This cancer develops in the ducts that transport milk to the nipple (galactophoric ducts)(3).

Invasive lobular carcinoma is responsible for breast cancer in 15% of cases. This cancer develops in the lobules of the breast, the milk-producing glands(3).

Other rare forms are involved in 10% of cases(3).

Treatment of breast cancer

Breast cancer treatment depends on a number of factors, including the stage, type and extent of the cancer.

In localised stages, treatment is curative and includes locoregional and systemic treatments. Breast surgery and surgery of the axillary lymph nodes on the affected side is then systematic. Depending on various prognostic and predictive factors and the type of surgery, chemotherapy and/or hormone therapy and/or targeted antibody therapy and/or radiotherapy may be carried out(3,10,11).

In the case of metastatic breast cancer, the cancer cells have spread beyond the breast to other parts of the body; treatment cannot therefore be curative but is essentially based on systemic treatments (chemotherapy, hormone therapy, targeted therapies)(3).

The aim is to increase patients' survival and improve their quality of life. Treatment therefore includes comprehensive care with psychological, social and dietary monitoring. Supportive care deals with the consequences of the disease and its treatment, and may include pain management, nutrition, adapted physical activity, fertility and sexuality, socio-aesthetic advice, etc.(3).

Prevention and life after breast cancer

Follow-up care for patients with breast cancer is important, and requires a multidisciplinary approach to reduce the risk of recurrence and improve quality of life(3).

Follow-up consultations may therefore be set up, with the aim of detecting local or distant recurrences and the occurrence of a new cancer, identifying and managing late complications linked to treatment, monitoring quality of life, organising supportive care, providing medico-social support, and taking a global medical approach to the various health risks to be prevented(3).

This follow-up consists of a clinical examination every 3 to 6 months for 5 years, then every year for the rest of the patient's life. A mammogram and breast ultrasound may be carried out every year for life(3).

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  1. Brown, J., Amend, S., Austin, R., Gatenby, R., Hammarlund, E., & Pienta, K. (2023). Updating the Definition of Cancer. Molecular Cancer Research, 21, 1142 - 1147. https://doi.org/10.1158/1541-7786.MCR-23-0411.
  2. Collège National des Enseignants en Cancérologie, Cancérologie, 3ème édition actualisée, R2C, Med-line édition
  3. Tumeurs du sein, Chapitre 22, Item 312, Collège National des Enseignants en Cancérologie, Cancérologie, 3ème édition actualisée, R2C, Med-line édition
  4. Daly, A., Rolph, R., Cutress, R., & Copson, E. (2021). A Review of Modifiable Risk Factors in Young Women for the Prevention of Breast Cancer. Breast Cancer : Targets and Therapy, 13, 241 - 257. https://doi.org/10.2147/BCTT.S268401.
  5. Sun, Y., Zhao, Z., Yang, Z., Xu, F., Lu, H., Zhu, Z., Shi, W., Jiang, J., Yao, P., & Zhu, H. (2017). Risk Factors and Preventions of Breast Cancer. International Journal of Biological Sciences, 13, 1387 - 1397. https://doi.org/10.7150/ijbs.21635.
  6. Feng, Y., Spezia, M., Huang, S., Yuan, C., Zeng, Z., Zhang, L., Ji, X., Liu, W., Huang, B., Luo, W., Liu, B., Lei, Y., Du, S., Vuppalapati, A., Luu, H., Haydon, R., He, T., & Ren, G. (2018). Breast cancer development and progression: Risk factors, cancer stem cells, signaling pathways, genomics, and molecular pathogenesis. Genes & Diseases, 5, 77 - 106. https://doi.org/10.1016/j.gendis.2018.05.001.
  7. Koo, M., Wagner, C., Abel, G., Mcphail, S., Rubin, G., & Lyratzopoulos, G. (2017). Typical and atypical presenting symptoms of breast cancer and their associations with diagnostic intervals: Evidence from a national audit of cancer diagnosis. Cancer Epidemiology, 48, 140 - 146. https://doi.org/10.1016/j.canep.2017.04.010.
  8. Hester, R., Hortobagyi, G., & Lim, B. (2021). Inflammatory breast cancer: early recognition and diagnosis is critical.. American journal of obstetrics and gynecology. https://doi.org/10.1016/j.ajog.2021.04.217.
  9. Coleman, C. (2017). Early Detection and Screening for Breast Cancer.. Seminars in oncology nursing, 33 2, 141-155 . https://doi.org/10.1016/j.soncn.2017.02.009.
  10. Moo, T., Sanford, R., Dang, C., & Morrow, M. (2018). Overview of Breast Cancer Therapy.. PET clinics, 13 3, 339-354 . https://doi.org/10.1016/j.cpet.2018.02.006.
  11. Vorobiof, D. (2016). Recent advances in the medical treatment of breast cancer. F1000Research, 5. https://doi.org/10.12688/f1000research.9619.1.