A risk factor is anything that can affect or modulate the development of a disease and is not determined by a single trigger but by the complex interaction of multiple elements. There are two different types of risk factors: those that cannot be changed (age, gender, genetic makeup, breastfeeding) and those that can be changed, which depend strictly on our individual choices, such as diet, smoking, level of physical activity, and protection of the skin from sunlight.

The most common factors linked with developing breast cancer are sex and age. Breast cancer occurs predominantly in women,¹ and the likelihood of being diagnosed increases gradually as people get older, with most cases found in women over 50.³ It is also important to remember that nearly half of the women who develop breast cancer have no specific risk factors other than their sex and age.²

Other risk factors, such as having family members (a mother or sister for example) who have had breast cancer, increase the chance of developing breast cancer as well. We now know that certain inherited gene mutations, such as BRCA1, BRCA2, and PALB2, are associated with an elevated risk.^1,2 Exposure to ionizing radiation also contributes to increased risk. Exposure to oestrogen–such as early puberty, late menopause, use of combined oestrogen–progestogen oral contraceptives, or post-menopausal hormone therapy–have been shown to increase the risk of developing breast cancer.^1,4

Modifiable lifestyle risk factors include obesity and metabolic syndrome. Obesity is a recognized risk factor, probably linked to excess adipose tissue, which in postmenopausal women is the main source of circulating oestrogen synthesis, resulting in excessive hormonal stimulation of the mammary gland.⁵ Metabolic syndrome, characterized by the presence of at least three of the following factors: abdominal obesity, impaired glucose metabolism (diabetes or prediabetes), high lipid levels (cholesterol and/or triglycerides), and high blood pressure, increases the risk of cardiovascular disease but also of breast cancer. Metabolic syndrome is based on a genetic predisposition, but lifestyles based on low physical activity and high-calorie diets rich in animal fats and simple carbohydrates clearly contribute to its development. It follows that by acting on these modifiable risk factors through regular daily physical activity combined with a balanced diet (such as the Mediterranean diet), the risk of developing breast cancer could be reduced by improving women’s metabolic and hormonal balance.

Finally, lifestyle factors such as alcohol consumption and smoking have also been associated with a higher risk.^2,4 Alcohol has a clear link to breast cancer risk at any level, so keeping intake as low as possible provides additional protection.

For mothers who are able to, breastfeeding provides a small protective effect against breast cancer over the long term.^5,6

These approaches cannot eliminate risk entirely, but they can help reduce the likelihood of developing breast cancer. It is still important to remember that while healthy lifestyle choices matter, early detection is equally important. Screening plays a key role in finding breast cancer sooner, which has greatly contributed to improved survival.¹

In the early stages, breast cancer often develops silently, and many people will not experience any symptoms at all. This is why early detection through screening is so important. When symptoms do appear, they can vary widely and often depend on how advanced the cancer is.¹

The most common signs include a lump or thickening in the breast, which may be painless, and changes in breast size or shape. Other possible symptoms may include dimpling of the skin, redness, or a rash on or around the nipple. The nipple itself may change appearance, becoming inverted or producing abnormal discharge, sometimes with blood. Some people may notice pain or swelling in the breast that does not go away, or a lump in the armpit.^1,2

While most breast lumps are not cancerous, it is important to seek medical advice as soon as possible if you notice an unusual lump, even if it is painless. Cancerous lumps are more likely to be successfully treated when detected early, before they spread to nearby lymph nodes.¹

In more advanced stages, cancer cells can spread beyond the breast to other parts of the body. They often spread first to the lymph nodes under the arm, which may become swollen (though this may not always be noticeable to the touch). If the cancer reaches organs such as the lungs, liver, brain, or bones, it can lead to new symptoms, such as persistent headaches or bone pain.¹

Because breast cancer can be present without noticeable symptoms, screening plays a key role in detecting the disease early, when it is most treatable.

For women with no family history or known genetic risk, a standard mammography screening is recommended every two years for those aged 50 to 69. For women with a strong family history of breast cancer or known mutations in BRCA1, BRCA2, or other high-risk genes, enhanced surveillance may include more frequent imaging or screening starting at a younger age.³

Breast cancer is typically diagnosed through a combination of clinical examination, imaging tests, and a biopsy.^2,3 Together, these steps help confirm the presence of cancer, determine its type, and guide treatment decisions.

Clinical examination

The diagnostic process often begins with a medical examination involving palpation of the breasts and nearby lymph nodes. During this visit, the doctor will ask about any symptoms, personal or family history of breast cancer, and menopausal status. Blood tests may also be taken. If a suspicious finding is detected, further imaging, such as a mammogram and/or an ultrasound scan will be arranged.²

Imaging
Imaging includes medical techniques such as x-rays, sound waves, or magnetic fields to create pictures of the inside of the body. This is an important part of the diagnostic process and gives a clearer view of what is happening inside the breast. To diagnose breast cancer, commonly used imaging techniques are:

• Mammography: This is a low-dose x-ray that captures detailed images of the breast. It is particularly useful in identifying early signs of cancer, especially in women over 50. If any abnormalities are detected, further tests are performed.

• Ultrasound: Using high-frequency sound waves, an ultrasound helps determine whether a lump is solid or filled with fluid. It is also used to assess lymph nodes in the armpit region.

When breast cancer is suspected, a bilateral mammogram and ultrasound of both breasts and regional lymph nodes are usually performed.³

• MRI (Magnetic Resonance Imaging): This type of scan produces high-resolution images using strong magnetic fields and radio waves. MRI is not used routinely but may be recommended when standard imaging techniques do not provide clear results or, for example, in specific cases in women with breast implants, a family history of breast cancer, or suspected multiple cancers.³

Other advanced techniques, such as digital breast tomosynthesis, synthetic mammography, or contrast-enhanced mammography may be used when available, particularly if conventional imaging results are unclear.³

Biopsy and further testing

If imaging suggests the presence of a tumour, a biopsy is performed to confirm the diagnosis. This involves taking a sample of tissue using a needle guided by ultrasound, mammography, or MRI. The biopsy helps determine whether the tumour is cancerous and provides essential details about the type of cancer.²

In addition to analysing the tumour tissue, further tests may include lymph node biopsy, biomarker analysis, and genetic testing. These tests offer insight into how the cancer is likely to behave and respond to treatment, and whether inherited genetic mutations such as BRCA1 or BRCA2 are involved.²

Breast cancer is not a single disease; it can appear in different forms that vary in how quickly they grow, how likely they are to spread, and how they respond to treatment. To understand a cancer fully, doctors look at several key features, including where it started, how far it has progressed, and what is driving its behaviour. Having this information helps guide treatment decisions and provides a clearer idea of what to expect.²

Once breast cancer becomes invasive, doctors classify it by how far it has progressed:

• Early breast cancer has not spread beyond the breast or nearby lymph nodes under the arm. It is usually treated with surgery, often followed by additional treatments like medication or radiation.
• Locally advanced breast cancer has spread from the breast to nearby tissue or lymph nodes but has not reached other parts of the body. These cases may need medication to shrink the cancer before surgery.
• Metastatic breast cancer has spread to distant parts of the body, like the bones, lungs, liver, or brain. This stage is also known as Stage IV. Although it cannot be cured, it can often be controlled with ongoing treatment.
• Advanced breast cancer is a term used to describe both metastatic and locally advanced breast cancer that cannot be operated on right away.

Beyond these general features, breast cancers can also differ at the biological level. Some rely on certain hormones to grow, while others produce specific proteins or follow distinct genetic patterns. These characteristics allow doctors to classify breast cancers into subtypes. Subtyping is usually done using tests performed on the cancer sample taken during a biopsy or after surgery, and may be complemented by additional tests that show how quickly the cells are dividing or how genes are being expressed. Identifying the subtype helps your care team tailor treatment more precisely to your individual situation.^2,3

Two early conditions related to breast cancer are ductal carcinoma in situ (DCIS) and lobular neoplasia. DCIS is a non-invasive condition in which the abnormal cells remain confined to the milk ducts. Although DCIS is not yet invasive cancer, it can develop into one if left untreated. Lobular neoplasia, previously known as lobular carcinoma in situ (LCIS), involves abnormal changes in the lobules. While it is not cancer, it indicates an increased risk of developing breast cancer later in life.²