Breast Cancer Guide

Brief Description of Breast Structure

The breasts are composed of varying tissues, from very fatty to very dense. Within this tissue is a network of lobes. Each lobe consists of small, tube-like structures called lobules, which contain milk-producing glands. Small ducts connect the glands, lobules, and lobes, transporting milk from the lobes to the nipple. The nipple is located in the center of the areola, the darker area surrounding the nipple.

Blood vessels and lymph vessels also run through the breasts. Blood vessels nourish the cells by delivering oxygen and nutrients and also remove waste and carbon dioxide. Unlike blood vessels, lymph vessels carry fluids away from tissues. They connect to lymph nodes and the lymphatic system, which drains bodily wastes.

Lymph nodes are small bean-shaped organs that are part of the body's immune system and help fight infections. Clusters of lymph nodes are located in different areas of the body, such as the neck, groin, and abdomen. The regional lymph nodes of the breast are those near the breast, such as the lymph nodes under the armpit, called axillary lymph nodes.

About Breast Cancer

Cancer begins when healthy cells in the breast change and grow out of control, forming a mass or cluster of cells called a tumor. A tumor can be cancerous or non-cancerous, also called benign. A cancerous tumor is malignant, meaning it can grow and spread to other parts of the body. A benign tumor means the tumor can grow but has not spread.

Breast cancer is a type of cancer that forms in the tissues of the breast – usually in the ducts or lobules. Breast cancer can be categorized as either noninvasive or invasive. Breast cancer is also categorized by how advanced the disease is on early, locally advanced, and metastatic stages.

Additionally, breast cancer can be classified into subtypes based on hormonal and HER2 receptor status, as follows: luminal A-like - ER and PgR positive, HER2 negative tumors; luminal B-like - ER and/or PgR positive; HER2 positive or negative tumors; HER2 overexpression - ER and PgR negative, HER2 positive tumors; and basal-like - triple-negative tumors.

Although breast cancer most commonly spreads to nearby lymph nodes, in which case breast cancer is still considered a local disease, it can also spread further in the body through blood vessels and/or lymph nodes to areas such as the bones, lungs, liver, and brain. This is called metastatic cancer or stage IV breast cancer and is the most advanced stage of the disease.

Types of Breast Cancer

As already mentioned, female breasts are made up of lobules, milk ducts, fatty and connective tissue, and blood and lymph vessels. The lobules contain the glands that produce milk, and the milk ducts are the channels that connect the lobules to the nipple. Most malignant breast formations begin in the ducts—then we speak of ductal cancer, or in the lobules—then it is lobular cancer.

Ductal carcinoma originates from the cells that line the milk ducts, responsible for transporting milk from the breast lobules to the nipple. This is the most common type of breast cancer and can manifest in various forms, including ductal carcinoma in situ, invasive ductal carcinoma, tubular invasive ductal carcinoma, medullary invasive ductal carcinoma, mucinous invasive ductal carcinoma, papillary invasive ductal carcinoma, and cribriform invasive ductal carcinoma.

Lobular carcinoma is a form of breast cancer that begins in the lobules, the glandular structures in the breast responsible for milk production. Although less common than ductal carcinoma, lobular carcinoma represents a significant portion of breast cancer cases. Subtypes of lobular carcinoma include lobular carcinoma in situ, invasive lobular carcinoma, inflammatory carcinoma, Paget's disease, and phyllodes tumors.

Breast Cancer Subtypes

There are three main subtypes of breast cancer, determined by conducting specific tests on a tumor sample to identify its characteristics. These tests will help your doctor learn more about your cancer and recommend the most effective treatment plan.

Testing the tumor sample can determine if the cancer has: 

• Positive hormonal receptors. Breast cancer expressing estrogen receptors (ER) and/or progesterone receptors (PR) is called 'hormone receptor-positive'. These receptors are proteins found in cells. Tumors that have estrogen receptors are called "ER positive". Tumors that have progesterone receptors are called "PR positive". Only one of these receptors needs to be positive to call the cancer hormone receptor positive. This type of cancer may depend on the growth of the hormones estrogen and/or progesterone in the body. Hormone receptor-positive cancers can occur at any age, but are more common after menopause. About two-thirds of breast cancers have estrogen and/or progesterone receptors. Cancers without these receptors are called "hormone receptor negative". Breast cancer with positive hormone receptors is usually treated with hormonal therapy.
• HER2 positive. About 15% to 20% of breast cancers depend on a gene called human epidermal growth factor 2 (HER2) to grow. These types of cancer are called "HER2 positive" and have many copies of the HER2 gene or high levels of the HER2 protein. These proteins are also called 'receptors'. The HER2 gene produces the HER2 protein, which is found in cancer cells and is important for the growth of tumor cells. HER2-positive breast cancer grows faster. They can also be either positive or negative for hormonal receptors. Early-stage HER2-positive breast cancers are usually treated with HER2-targeted therapies. Cancers that do not have the HER2 protein are called "HER2 negative".
• Triple negative. If the tumor does not express ER, PR, and HER2, the tumor is called 'triple negative'. Triple-negative breast cancer accounts for about 10% to 20% of invasive breast cancers. Triple-negative breast cancer appears to be more common among younger women, especially younger black women and Hispanics. Triple-negative breast cancer is also more common among women with a BRCA1 gene mutation. Experts often recommend people with triple-negative breast cancer be tested for BRCA gene mutations.

Symptoms of Breast Cancer

The symptoms of breast cancer can vary significantly among individuals, and some may not have any symptoms, especially in the early stages of the disease. However, it's important to be vigilant and aware of potential signs, which can help in early detection, diagnosis, and treatment. Here are the most common symptoms of breast cancer:

• Lump or thickening - One of the most recognizable signs of breast cancer is the presence of a lump or thickening in the breast tissue, which can be felt as a distinct mass during self-examination or may be detected during a clinical breast examination.
• Changes in the size or shape of the breasts - Breast cancer can cause changes in the size, shape, or contour of the breasts. This may manifest as asymmetry between the breasts or other noticeable changes in their appearance over time.
• Skin changes - Skin changes on or around the breasts can indicate breast cancer. These changes may include redness, swelling, dimpling, or puckering of the skin, resembling the texture of an orange peel.
• Changes in the nipples - Changes in the nipples, such as inversion, retraction, or the discharge of a fluid other than breast milk, may be indicative of breast cancer.
• Pain or discomfort in the breasts - While breast pain is a common symptom and often not related to cancer, persistent or unexplained breast pain should not be overlooked and should be evaluated by a medical professional.
• Swelling in the armpit or collarbone area - Lymph nodes in the armpit and collarbone area may swell or become enlarged in response to the spread of breast cancer to nearby lymph nodes.

It's important to note that experiencing one or more of these symptoms does not necessarily mean that a person has breast cancer, as many other conditions can cause similar changes. However, if you notice any unusual changes in your breasts, you should consult a medical professional for a comprehensive evaluation and appropriate diagnostic testing.

Risk Factors for Breast Cancer 

A risk factor for breast cancer refers to any characteristic that increases the likelihood that an individual will develop the disease. They can be influenced by genetic factors, environmental factors, or lifestyle choices, and while the presence of one or more risk factors does not guarantee the development of breast cancer, it may increase the overall risk.

Some risk factors are beyond an individual's control, such as age, gender, and family history, while others can be controlled through lifestyle changes or medical interventions.

The most common risk factors for breast cancer include:

• Gender - Being female is the most significant risk factor for breast cancer. Although men can develop breast cancer, it is much less common than in women.
• Age - The risk of breast cancer increases with age, with most cases diagnosed in women over the age of 50.
• Family history and genetics - A family history of breast cancer, especially in first-degree relatives such as a mother, sister, or daughter, and certain genetic mutations, such as BRCA1 and BRCA2, significantly increase the risk.
• Personal history of breast cancer - Individuals who have previously been diagnosed with breast cancer have an increased risk of developing new cancer in the same or opposite breast.
• Dense breast tissue - Women with dense breast tissue, identified on mammograms, may have a higher risk of breast cancer.
• Reproductive factors - Factors such as early onset of menstruation, late onset of menopause, having no children, or having the first child after age 35, can affect the risk of breast cancer.
• Hormone replacement therapy - Long-term use of hormone replacement therapy, especially estrogen plus progestin, can increase the risk of breast cancer.
• Lifestyle factors - Some lifestyle choices, such as excessive alcohol consumption, smoking, lack of physical activity, and a high-fat diet, can contribute to an increased risk of breast cancer.
• Exposure to radiation - Previous exposure to radiation therapy, especially in childhood or adolescence, can increase the risk of developing breast cancer later in life.
• Obesity and weight gain - Being overweight or obese, especially after menopause, is linked to an increased risk of breast cancer.

Staging of Breast Cancer 

Staging is a method to describe the extent of breast cancer, including the size of the tumor, whether it has spread to the lymph nodes, whether it has metastasized to distant parts of the body, and its biomarkers.

Staging can be clinical and/or pathological. Clinical staging is based on the results of tests performed before surgery, which may include physical exams, mammograms, ultrasound, and MRI scans. Pathological staging is based on findings during surgery to remove breast tissue and lymph nodes. The results are usually available a few days after the operation. Generally, pathological staging provides the most information to determine a patient's prognosis. Knowing the stage helps the doctor recommend the best type of treatment and can help predict the patient's prognosis, as well as the chance of recovery.

TNM Staging System 

The most commonly used tool that doctors use to describe the stage is the TNM system. Doctors use the results of diagnostic tests and scans to answer these questions:

• Tumor (T): How large is the primary tumor in the breast? What are its biomarkers?
• Node (N): Has the tumor spread to the lymph nodes? If so, where, what size, and how many?
• Metastasis (M): Has the cancer spread to other parts of the body?

Tumor (T)

Using the TNM system, 'T' plus a letter or number (0 to 4) is used to describe the size and location of the tumor. The size of the tumor is measured in centimeters (cm). One centimeter is roughly equal to the width of a standard pen or pencil.

The stage can also be subdivided into smaller groups that help describe the tumor in even more detail. Specific information about the tumor stage is provided below:

• TX: The primary tumor cannot be assessed.
• T0 (T zero): No evidence of breast cancer.
• Tis: Refers to carcinoma in situ. The cancer is confined within the ducts of breast tissue and has not spread to surrounding breast tissue. There are 2 types of breast carcinoma in situ:
• Tis (DCIS): DCIS is non-invasive cancer but if not removed, it could later develop into invasive breast cancer. DCIS means that cancer cells are found in the ducts of the breast and have not spread beyond the layer of tissue where they started.
• Tis (Paget's disease): Paget's disease is a rare form of early, non-invasive cancer found only in the skin cells of the nipple. Sometimes Paget's disease is associated with invasive breast cancer. If there is invasive breast cancer, it is classified according to the stage of the invasive tumor.
• T1: The tumor in the breast is 20 millimeters (mm) or smaller at its widest area. Then this stage is divided into 4 sub-stages depending on the size of the tumor:
• T1mi is a tumor that is 1 mm or smaller.
• T1a is a tumor that is larger than 1 mm but 5 mm or smaller.
• T1b is a tumor that is larger than 5 mm but 10 mm or smaller.
• T1c is a tumor that is larger than 10 mm but 20 mm or smaller.
• T2: The tumor is larger than 20 mm but not larger than 50 mm.
• T3: The tumor is larger than 50 mm.
• T4: The tumor falls into one of the following groups:
• T4a means the tumor has grown into the chest wall.
• T4b is when the tumor has grown into the skin.
• T4c is cancer that has grown into both the chest wall and the skin.
• T4d is inflammatory breast cancer.

Node (N)

In the TNM staging system, "N" stands for lymph nodes. These small bean-shaped organs help fight infection. The lymph nodes close to where the cancer started are called regional lymph nodes. Regional lymph nodes include:

• Lymph nodes located under the arm are called axillary lymph nodes.
• Lymph nodes located above and below the collarbone.
• Lymph nodes located beneath the breastbone are called internal mammary lymph nodes.
• Lymph nodes in other parts of the body are called distant lymph nodes. Below is the description and notation of the result:
• NX: Lymph nodes cannot be assessed.
• N0: One of the following: No cancer is found in the lymph nodes. Or there are only areas of cancer smaller than 0.2 mm in the lymph nodes.
• N1: Cancer has spread to 1 to 3 axillary lymph nodes and/or internal mammary lymph nodes. If the cancer in the lymph node is larger than 0.2 mm but 2 mm or smaller, it is called 'micrometastatic' (N1mi).
• N2: Cancer has spread to 4 to 9 axillary lymph nodes. Or it has spread to internal mammary lymph nodes but not to axillary lymph nodes.
• N3: Cancer has spread to 10 or more axillary lymph nodes or has spread to lymph nodes located below the collarbone or the collarbone itself. It may have also spread to internal mammary lymph nodes. Cancer that has spread to the lymph nodes above the collarbone, called supraclavicular lymph nodes, is also described as N3.

Metastasis (M)

"M" in the TNM system describes whether the cancer has spread to other parts of the body, called metastases. This is no longer considered early or locally advanced cancer.

• MX: Distant spread cannot be assessed.
• M0: There is no evidence of distant metastases.
• M0 (i+): There are no clinical or radiographic proofs of distant metastases. However, there are microscopic proofs of tumor cells in the blood, bone marrow, or other lymph nodes that are no larger than 0.2 mm.
• M1: There is evidence of metastases in another part of the body, which means there are breast cancer cells growing in other organs.

Breast Cancer Staging Groups

Stages range from 0 to IV, with 0 being the earliest stage and IV being the most advanced.

• Stage 0 (Ductal Carcinoma In Situ - DCIS): Cancer cells are confined to the ducts of the breast and have not invaded surrounding tissues. At this stage, the cancer is considered non-invasive and has an excellent prognosis with early treatment. Also referred to as non-invasive or in situ cancer (Tis, N0, M0).
• Stage IA: The tumor is small, invasive, and has not spread to the lymph nodes (T1, N0, M0).
• Stage IB: Cancer has spread to the lymph nodes with cancer in the lymph node larger than 0.2 mm but smaller than 2 mm. Or, there is no evidence of a tumor in the breast, or the tumor in the breast is 20 mm or smaller (T0 or T1, N1mi, M0).
• Stage IIA: Any of the following conditions:
• No evidence of a tumor in the breast, but cancer has spread to 1 to 3 axillary lymph nodes. It has not spread to distant parts of the body (T0, N1, M0).
• The tumor is 20 mm or smaller and has spread to 1 to 3 axillary lymph nodes (T1, N1, M0).
• The tumor is larger than 20 mm but not larger than 50 mm and has not spread to the axillary lymph nodes (T2, N0, M0).
• Stage IIB: Any of these conditions:
• The tumor is larger than 20 mm but not larger than 50 mm and has spread to 1 to 3 axillary lymph nodes (T2, N1, M0).
• The tumor is larger than 50 mm but has not spread to the axillary lymph nodes (T3, N0, M0).
• Stage IIIA: The tumor of any size has spread to 4 to 9 axillary lymph nodes or to internal mammary lymph nodes. It has not spread to other parts of the body (T0, T1, T2, or T3; N2; M0). Stage IIIA can also be a tumor larger than 50 mm that has spread to 1 to 3 axillary lymph nodes (T3, N1, M0).
• Stage IIIB: The tumor has spread to the chest wall or has caused swelling or ulceration of the breast, or is diagnosed as inflammatory breast cancer. It may or may not have spread to up to 9 axillary or internal mammary lymph nodes. It has not spread to other parts of the body (T4; N0, N1, or N2; M0).
• Stage IIIC: Tumor of any size that has spread to 10 or more axillary lymph nodes, internal mammary lymph nodes, and/or lymph nodes beneath the collarbone. It has not spread to other parts of the body (any T, N3, M0).
• Stage IV (Metastatic): The tumor can be any size and has spread to other organs, such as bones, lungs, brain, liver, distant lymph nodes, or the chest wall (any T, any N, M1).

Diagnosis of breast cancer

Breast cancer diagnosis usually involves several steps to confirm the presence of cancer, determine its type, stage and plan appropriate treatment. 

Clinical breast examination

During a clinical breast examination, the doctor carefully examines the breasts and lymph nodes, feeling for lumps, bumps or other abnormalities, changes in size, shape or texture of the skin. The medical professional will ask you for information about any family history of breast cancer and whether you are menopausal. 

A blood sample and other blood tests may be ordered. If a breast tumor is suspected, you will be referred for imaging.

Diagnostic imaging

Diagnostic imaging in women with suspected breast cancer includes mammography, ultrasonography and/or MRI.

• Mammography - Mammography is the primary screening tool for breast cancer. It involves compressing breast tissue between two plates while x-ray images are taken. Mammograms can detect tumors, calcifications, or other suspicious growths that may indicate the presence of cancer.
• Ultrasonography - Breast ultrasonography uses high-frequency sound waves to create images of breast tissue. It is usually used to further evaluate abnormalities found on mammograms, or to differentiate between solid masses and fluid-filled cysts. When conducting this breast cancer screening, the doctor examines the breasts and lymph nodes in the armpit area with a handheld ultrasound device.
• MRI (magnetic resonance imaging) - A breast MRI provides detailed images of breast tissue using a combination of magnetic fields and radio waves. It is often used in high-risk individuals or to assess the extent of cancer in women diagnosed with breast cancer. The examination takes place while lying in the tube of the machine for 15 to 90 minutes.

Biopsy

A biopsy is the definitive diagnostic test for breast cancer. It gives the doctor information about the type of breast cancer and helps with treatment planning. The procedure involves removing a small sample of tissue or cells from the suspicious area for examination under a microscope. Biopsy methods include: 

• Fine needle aspiration biopsy - a thin needle is used to extract cells or fluid from a breast lump or cyst.
• Core needle biopsy - a larger needle removes a small core of tissue from the suspicious area.
• Surgical biopsy - a surgical procedure is performed to remove part or all of a suspicious area for examination.

Evaluation of pathology

After biopsy, tissue samples are sent to a pathologist for examination. The pathologist analyzes the samples to determine if cancer cells are present, what their status is, and other characteristics such as hormone receptor status and HER2 expression.

Staging tests

Additional tests may be done to determine the stage of breast cancer, including imaging tests (CT scans, PET scans, bone scans) to see if the cancer has spread to other parts of the body.

• CT scan (computed tomography) - CT scans use X-ray technology to create detailed cross-sectional images of the body. They are often used to assess whether cancer has spread to nearby lymph nodes or other organs.
• PET scan (positron emission tomography) - PET scans use a radioactive tracer to detect cancer cells throughout the body. They are useful in identifying distant metastases.
• Bone scan (DEXA test) - Bone scans are used to detect cancer that has spread to the bone, a common site of metastasis in breast cancer.

Multidisciplinary consultation

Once diagnostic testing is complete, a multidisciplinary team of healthcare professionals, including surgeons, medical oncologists, radiation oncologists and pathologists, meet to review the results and develop a comprehensive treatment plan tailored to the patient's specific diagnosis and needs.

Methods for early detection of breast cancer

Early detection plays a critical role in breast cancer treatment and leads to a better prognosis and increased chances of survival. There are three main methods of early detection.

Breast self-examination

Breast self-examination involves checking the breasts regularly for any changes or abnormalities. It is recommended that such self-examination be done every month, usually a few days after the end of menstruation when the breast tissue is less swollen and sensitive. 

During self-examination, look for changes in the size, shape or contour of the breasts, as well as indentations in the skin, nipple inversion or abnormal discharge. Palpate the breasts in different positions, lying down and standing up, to get a better feel for any lumps or thickening. 

Annual mammography

Mammography is the primary screening for breast cancer in women without symptoms. It is an X-ray of breast tissue that can detect tumors or other abnormalities that may not be noticeable during a physical examination. It is recommended that women aged 40 and older undergo annual mammography. 

Women at higher risk for breast cancer, such as those with a family history of the disease or certain genetic mutations, may need to begin screening at an earlier age or undergo additional imaging tests, such as breast MRI, periodically.

Annual medical examination

A clinical breast exam is a physical examination of the breasts performed by a specialist. During the exam, the medical professional visually inspects the breasts for changes in size, shape or texture of the skin and palpates the breast tissue to feel for lumps, thickening or other abnormalities. This type of examination is recommended annually for women over the age of 20.

Breast self-examination - how to do it

1. Visual inspection - stand in front of a mirror with your arms relaxed at your sides. Look at your breasts for changes in size, shape or contour. Check for indentations, wrinkling or redness of the skin, and any visible lumps, swelling or distortion.
2. Examination with raised arms - raise your arms above your head and observe your chest in the mirror. Look for the same changes as in the previous step, noting differences in breast symmetry and any signs of changes in skin texture or nipple retraction.
3. Palpate in an upright position - use the pads of your fingers to palpate your breasts in an upright position. Start at the outer edge and move inward in a circular motion, covering the entire breast and underarm area. Apply varying levels of pressure to feel for lumps, knots or bumps in the breast tissue.
4. Supine palpation - lie on your back with a pillow under your right shoulder and your right arm behind your head. Use your left hand to examine your right breast, using the same circular motion described in the previous step. Repeat the process for the left breast.
5. Nipple examination - gently squeeze each nipple between your thumb and index finger, checking for discharge or changes in the shape or color of the nipple. Note any abnormalities such as turning, flaking or crusting.

Repeat the steps regularly - perform these self-examination steps once a month, ideally a few days after the end of your menstrual cycle, when breast tissue is least likely to be swollen or sensitive. Keep track of any changes you notice and report them to your doctor.

Breast cancer treatment

There are several types of breast cancer treatment, and choosing the right one depends on factors such as the type and stage of cancer, as well as the patient's general health and preferences. Basically, treatment is divided into adjuvant and neoadjuvant.

Non-adjuvant treatment is a pre-operative treatment that aims to reduce the size of the tumor and affected lymph nodes so that surgery can be performed. This type of treatment is widespread as an approach to breast cancer, and is particularly important in HER2 positive tumors and triple negative tumors. Neoadjuvant treatment includes chemotherapy, targeted therapy, immunotherapy and hormonal therapy.

Adjuvant treatment refers to all types of treatment that take place after surgery. The aim of this type of treatment is to reduce the risk of recurrence. For breast cancer, adjuvant treatment may be chemotherapy, targeted therapy, hormone therapy, or immunotherapy.

Surgery is often the first step of breast cancer treatment and may involve removal of the tumor (lumpectomy or mastectomy) and nearby lymph nodes. The goal of surgery is to remove as much of the cancerous tissue as possible while preserving the appearance and function of the breast.

Visit the Treatment page to learn more about the methods available for breast cancer.