How Is Breast Cancer Diagnosed?

Breast cancer is the leading cause of cancer in women worldwide. In France, about one in eight women will face this diagnosis in her lifetime. When detected early, however, it offers very good chances of recovery thanks to medical advances and screening programs. But how exactly is this diagnosis made? What are the steps, from the first signs to medical confirmation?

This article offers a complete overview of the methods used to diagnose breast cancer, with an emphasis on prevention, clinical examinations, medical imaging, and confirmatory tests.

1. The importance of early detection

An early diagnosis considerably increases the chances of recovery and reduces the burden of treatment. The earlier a tumor is detected, the smaller it is, the less likely it is to have spread, and the more targeted and effective the treatments will be.

There are two main levers to promote this detection:

• Self-monitoring: women are encouraged to stay alert to changes in their breasts (lumps, discharge, changes to the skin or nipple).
• Organized screening: in France, it is offered every two years to women aged 50 to 74, through a mammogram that is 100% covered by health insurance.

But beyond screening, when a suspicious sign appears, a precise care pathway is put in place.

2. The initial medical consultation

2.1 The clinical examination

The first step in the diagnosis is often the consultation with the primary care physician or the gynecologist. The doctor:

• asks the patient about her personal and family history (in particular the presence of breast or ovarian cancer in the family);
• assesses risk factors (age, hormone treatments, lifestyle, etc.);
• performs an examination of the breasts and lymph node areas (axillary, supraclavicular).

This examination may reveal a mass, an asymmetry, nipple retraction, redness, or skin thickening.

2.2 Referral for imaging

If there is any doubt or an abnormal finding on palpation, the doctor immediately prescribes additional tests, mainly a mammogram and a breast ultrasound.

3. Medical imaging

3.1 The mammogram

The mammogram is the reference examination for exploring the breast. It is an X-ray that uses low doses of radiation to visualize the internal structure of the breast.

• It can detect abnormalities that cannot be felt on palpation, such as microcalcifications.
• It is performed on both breasts for comparison.
• If there is any doubt, additional views or a digital mammogram with magnification may be requested.

3.2 The breast ultrasound

Often complementary to the mammogram, ultrasound uses sound waves to clarify the nature of an abnormality. In particular, it can distinguish a solid lesion (potentially cancerous) from a benign cyst.

It is especially useful in young women or those with dense breasts, where the mammogram may be harder to read.

3.3 The breast MRI

Magnetic resonance imaging (MRI) is not routine, but it is used in specific cases:

• very dense breasts or breast implants,
• suspected multifocal tumor,
• monitoring of patients at high genetic risk.

MRI offers increased sensitivity, but its interpretation requires great expertise.

4. Confirmatory tests: the biopsy

Imaging may reveal a suspicious abnormality, but only a histological examination can confirm a cancer diagnosis.

4.1 The core needle biopsy

The most common method is the core needle biopsy guided by ultrasound or mammography. Under local anesthesia, the doctor inserts a fine needle that removes several tissue fragments.

4.2 The macrobiopsy (or stereotactic biopsy)

It allows a larger sample to be taken, which is useful in cases of microcalcifications that are difficult to analyze.

4.3 Pathological analysis

The samples are then sent to the laboratory. The pathologist determines:

• whether the lesion is benign, precancerous, or cancerous,
• the type of breast cancer (ductal carcinoma, lobular carcinoma, etc.),
• the grade (aggressiveness of the tumor),
• the presence or absence of hormone receptors (estrogen, progesterone),
• possible overexpression of the HER2 gene.

This information is essential to guide the choice of treatment.

5. Additional tests after diagnosis

Once the cancer is confirmed, the doctor assesses how far it has spread in order to propose an appropriate treatment strategy.

5.1 Locoregional staging

The area close to the breast is examined:

• axillary ultrasound to check for involvement of the lymph nodes,
• sometimes a lymph node biopsy (sentinel node).

5.2 Distant staging

Depending on the stage, other tests may be prescribed:

• chest-abdomen-pelvis CT scan,
• bone scan,
• PET scan (positron emission tomography).

These tests are used to look for possible metastases.

6. The role of genetic and molecular testing

In some cases, particularly if several cases of breast or ovarian cancer are present in the family, a genetic test may be offered. It looks for mutations such as BRCA1 or BRCA2, which increase the risk of developing breast cancer.

In addition, more refined molecular analyses (gene expression profiling) can help guide the most appropriate treatments.

7. The emotional journey of diagnosis

Beyond the technical examinations, it is essential to remember the psychological dimension of receiving a diagnosis. Waiting for results can be a period of great anxiety. Medical teams often offer psychological support and put patients in touch with support associations.

The announcement of a cancer diagnosis is structured by a framework known in France as the announcement program, which provides for a medical phase (clear explanations, treatment plan) and a support phase (listening, support, guidance).