Breast Cancer

Clinical Features

The tumor most often develops in the ducts (ductal carcinoma) or lobules (lobular carcinoma) of the breast. There are invasive forms that can spread to surrounding tissues and organs, and non-invasive forms (in situ) that remain confined to the original tissue. The main difference between malignant and benign tumors is the ability to metastasize through the lymphatic system and bloodstream.

Epidemiology and Prevalence

The increase in the number of diagnosed cases is partly due to improved diagnostic techniques and greater awareness. Modern screening methods, particularly mammography, allow for early detection of the disease, which previously might have been missed. In countries with well-developed healthcare systems, such as the USA, Canada, and European nations, high detection rates are associated with active screening programs. Despite the availability of modern treatments, mortality remains high, partly due to late presentation for medical care.

Causes and Risk Factors

The exact causes of breast cancer are not fully understood, but researchers have identified several factors that may increase the likelihood of its development.

Non-Modifiable Risk Factors:

• Gender and Age. Breast cancer predominantly occurs in women rather than men. The risk increases with age, especially after the age of 50. The primary risk group is women aged 50-70.

• Genetic Predisposition. Mutations in the BRCA1 and BRCA2 genes significantly increase the risk. Women with a family history of breast or ovarian cancer are at higher risk. Approximately 5-10% of cases are hereditary.

• Individual History. Women who have previously been diagnosed with breast cancer, or who have had benign breast tumors (such as fibroadenoma or atypical hyperplasia), are at increased risk of primary or recurrent malignant tumors.

Modifiable Risk Factors:

• Hormonal Factors. Early onset of menstruation, late menopause, absence of pregnancy or late childbirth, as well as long-term use of hormonal contraceptives or postmenopausal hormone therapy. Estrogen produced in the body can promote tumor development if its levels remain elevated for a prolonged period.

• Diet and Excess Weight. Being overweight, especially after menopause, and a high-fat diet contribute to cancer development.

• Physical Activity. Lack of physical activity increases the risk. Regular exercise, on the other hand, can reduce the likelihood of developing the disease.

• Radiation Exposure. Radiation therapy to the chest at a young age, especially before the age of 30, increases the risk of breast cancer.

• Smoking and Alcohol. Smoking and excessive alcohol consumption are known risk factors for cancer.

Classification and Stages

The classification of breast cancer helps guide treatment strategies and predict disease outcomes. It is based on tumor size, lymph node involvement, and the presence of metastases.

TNM Classification

The TNM system assesses three main parameters:

• T (Tumor) – Tumor Size and Spread:

  • T1: Tumor up to 2 cm

  • T2: Tumor from 2 to 5 cm

  • T3: Tumor larger than 5 cm

  • T4: Tumor extends to surrounding tissues

• N (Nodes) – Lymph Node Involvement:

  • N0: No lymph node involvement

  • N1: Involvement of a few axillary nodes

  • N2: Significant lymph node involvement

  • N3: Lymph node metastases

• M (Metastasis) – Presence of Distant Metastases:

  • M0: No distant metastases

  • M1: Metastases in distant organs (lungs, liver, bones, etc.)

Histological Types

• Invasive Ductal Carcinoma – the most common type, originates in the milk ducts and can spread to surrounding tissues.

• Invasive Lobular Carcinoma – starts in the lobules, tends to affect both breasts, and is generally more aggressive.

• Non-Invasive Forms:

  • Ductal Carcinoma In Situ (DCIS) – tumor is confined to the ducts.

  • Lobular Carcinoma In Situ (LCIS) – tumor is confined to the breast lobules.

Non-invasive forms have a favorable prognosis and are often treated without radical interventions when detected early.

Molecular Subtypes of Breast Cancer

Modern oncology identifies several molecular subtypes of breast cancer based on hormone receptor status and HER2 protein expression. These subtypes play a crucial role in treatment selection and prognosis:

• Luminal A – Hormone-dependent subtype (positive for estrogen and/or progesterone receptors, HER2-negative, low proliferation rate). It has the most favorable prognosis and responds well to hormonal therapy.

• Luminal B – Hormone-dependent subtype with higher proliferation or HER2 positivity. Often requires combination therapy: hormonal treatment and chemotherapy.

• HER2-Positive – Tumors with HER2 protein overexpression, but negative for estrogen and progesterone receptors. These forms are more aggressive but respond well to targeted therapies (e.g., trastuzumab).

• Triple-Negative Breast Cancer (TNBC) – Lacks expression of estrogen, progesterone, and HER2 receptors. This is the most aggressive subtype with limited options for targeted therapy. Treatment is primarily based on chemotherapy and, in some cases, immunotherapy.

Symptoms and Signs

Breast cancer often develops without noticeable symptoms in its early stages, making diagnosis challenging without regular screening. However, as the disease progresses, characteristic symptoms may appear:

• Lump or mass in the breast;

• Changes in breast shape or size;

• Breast pain;

• Changes in breast skin (redness, thickening, dimpling, or characteristic puckering);

• Nipple discharge (clear, bloody, or with clots);

• Nipple retraction or changes in its shape, as well as ulcers or cracks on its surface;

• Enlarged lymph nodes in the armpit area.

How to Perform Breast Self-Examination

Breast self-examination is an important element in the early detection of cancer. However, it does not replace visiting a doctor and undergoing regular screening tests.

1. Visual Inspection in Front of a Mirror
   Stand in front of a mirror and carefully examine your breasts in different body positions: upright and leaning forward. Pay attention to changes in shape, size, skin texture, the appearance of bulges, or nipple retraction.

2. Palpation of the Breasts
   Use your fingertips to feel your breasts, moving in circular motions from the outer edge toward the center. Pay attention to any lumps or painful areas.

3. Checking the Underarm Areas
   Be sure to check the underarm areas for enlarged lymph nodes, which may indicate cancer metastasis.

4. Palpation While Lying Down
   For a more thorough examination, palpate your breasts while lying on your back. This helps to examine deeper tissues and detect changes in the deepest parts of the breast.

If you notice any changes during self-examination, you should immediately consult a doctor for further evaluation.

Early detection and timely medical attention are crucial for favorable outcomes. Marus, a service created to help patients navigate the healthcare system in Russia, can assist you in finding specialists, organizing diagnostics, and arranging treatment.

Diagnosis of Breast Cancer

A comprehensive approach is required for early detection of breast cancer, combining imaging and laboratory methods.

Imaging Diagnostics

• Mammography – the primary screening method using breast X-rays. It can detect tumors as small as 1 cm, significantly increasing treatment success rates.

• Breast Ultrasound – complements mammography, helping to assess the structure of the tumor and its relation to surrounding tissues.

• Breast MRI – used in complex cases for precise tumor evaluation and surgical planning.

• Biopsy – confirms the diagnosis by taking a tissue sample from the suspicious area.

• Elastography – evaluates tissue stiffness, helping distinguish between benign and malignant tumors.

Laboratory Tests

• Histological Examination – performed after a biopsy to determine the exact type of tumor. This is the first step in confirming malignancy and its specific features. Based on histology results, further tests such as immunohistochemistry may be required.

• Immunohistochemical (IHC) Testing – a specialized method that identifies the expression of hormone receptors (estrogen and progesterone) and HER2/neu receptors in tumor cells. IHC results are critical for selecting personalized treatment: hormonal, targeted, or immunotherapy.

• Molecular Genetic Testing – detects hereditary mutations in genes such as BRCA1, BRCA2, and others (TP53, PALB2, CHEK2, etc.) associated with a higher risk of breast cancer. It may also assess tumor gene expression profiles (e.g., Oncotype DX, MammaPrint), which help predict disease aggressiveness and the need for chemotherapy. These tests are used for both prognostic and predictive purposes.

• Tumor Marker Tests – markers like CA 15-3 and CEA can help monitor treatment response but are not used for initial diagnosis due to low specificity.

In recent years, the detection of circulating tumor DNA (cfDNA) or circulating tumor cells (CTC) in the blood has been actively studied. These non-invasive "liquid biopsy" methods can monitor minimal residual disease, detect recurrences before clinical symptoms appear, and assess the tumor’s mutation profile in real time.

Breast Cancer Treatment Methods

The choice of treatment depends on the cancer stage, tumor type, overall patient health, and presence of metastases. A proper strategy often combines several therapies, either sequentially or simultaneously. The main treatment methods include surgery, chemotherapy, radiation therapy, hormone therapy, targeted therapy, and immunotherapy.

Surgical Treatment

Surgery is one of the primary treatments, especially in the early stages. The surgeon may remove just the tumor and surrounding tissues (breast-conserving surgery) or the entire breast (mastectomy) if the tumor is large or multifocal.

• Breast-Conserving Surgery preserves the breast by removing only the affected area. This is suitable for small tumors without lymph node involvement.

• Mastectomy involves the complete removal of the breast and, if necessary, nearby lymph nodes.

• Lymph Node Dissection is performed if there is a risk of lymph node metastasis.

Breast reconstruction is possible after a mastectomy, helping restore appearance and improve quality of life.

Chemotherapy

Chemotherapy targets rapidly dividing cancer cells and is often used before surgery (to shrink the tumor) or after surgery (to reduce the risk of recurrence). Although it may cause side effects (nausea, weakness, hair loss), modern drugs are better tolerated.

Radiation Therapy

Radiation therapy helps destroy remaining cancer cells after surgery or is used for metastatic disease. It involves targeted exposure to high-energy beams and typically does not require hospitalization.

Hormone Therapy

Hormone therapy is prescribed if the tumor is hormone receptor-positive (estrogen or progesterone sensitive). It blocks the effects of hormones on cancer cells and helps prevent recurrence. It can be used alone or in combination with other therapies.

Targeted Therapy

Targeted therapy precisely attacks specific molecules that promote tumor growth. It is particularly effective for HER2-positive cancers. This approach selectively targets cancer cells with minimal impact on healthy tissues and typically has fewer severe side effects.

Immunotherapy

Immunotherapy boosts the body’s own immune system to fight cancer. It is used in specific cancer types, especially in advanced stages when other treatments are insufficient

Prognosis

The prognosis of breast cancer depends on several factors, including disease stage, tumor type, patient age, metastasis presence, and treatment response. Thanks to advances in diagnostics and therapy, breast cancer has become a more treatable disease in recent decades, especially when detected early.

Women who undergo regular screening and follow medical lifestyle recommendations have a lower risk of developing the disease and higher chances of successful treatment. Early detection and timely therapy significantly reduce recurrence risks and improve patient outcomes.