Breast cancer: Symptoms, Causes, Risk factor, Diagnosis and Staging

Breast cancer is the most common cancer diagnosed in women after skin cancer where cancer forms in the cells of the breasts.

Updated: June 16, 2022

Breast cancer is the most common cancer diagnosed in women after skin cancer where cancer forms in the cells of the breasts.
Breast cancer can occur in both men and women, but most commonly occurs in women. It is also the second leading cause of cancer death in women after lung cancer. Due to factors such as earlier detection, a new personalized approach to treatment and a better understanding of the disease, the death rate from breast cancer has declined a bit in recent years. There are many types of breast cancer that differ in their capability of spreading to other body tissues.
Breast cancer is a disease that occurs when cells in breast tissue change or mutate and keep reproducing. These abnormal cells usually cluster together to form a tumor. When these abnormal cells invade other parts of the breast or when they spread or metastasize to other areas of the body through the bloodstream or lymphatic system, the tumor is called cancerous or malignant. Lymphatic system is a network of vessels and nodes in the body that plays a role in fighting infection. Breast cancer usually starts in the milk producing glands of the breast called lobules or the tube shaped ducts that carry milk from the lobules to the nipple. However, cancer can also begins in the fatty and fibrous connective tissue of the breast which is uncommon.

Symptoms of Breast cancer:

Signs and symptoms of breast cancer may vary from person to person. Often, there are no early warning signs of breast cancer. A lump may be too small to feel even if you have developed it. This the reason why breast cancer screening is so important. The screening is typically done by using mammography.
Early signs and symptoms of breast cancer that some women and men might experience include:

  • New lump in the breast or armpit, with or without pain. Lumps are often hard but can be soft as well. Not necessarily all lumps are breast cancer. Some lumps may be noncancerous changes or benign, fluid-filled cysts, but they should be checked by your physician.
  • Change in breast size or shape. There may be swelling, thickening, or shrinkage, especially in one breast.
  • Dimpling, pitting, or redness of the skin over your breast. Breast skin may take on the appearance of an orange peel.
  • Peeling, flaking, or scaling breast skin.
  • Red, thick, or scaly nipple.
  • Breast, nipple, or armpit pain.
  • Inverted nipple. A nipple could turn inward or flattens.
  • Nipple discharge which may be clear or bloody.
  • Redness or unusual warmth. This can be a sign of inflammatory breast cancer, a rare and aggressive form of the disease.
  • Swollen lymph nodes under the arm or around the collarbone, which could be a sign that breast cancer has spread.

If you find a lump or other change in your breast, a prompt evaluation should be done by your doctor even if a recent mammogram was normal.

Causes of Breast cancer:

Breast cancer is caused by a genetic mutation in the DNA of breast cancer cells. In genetic mutation, some breast cells begin to grow abnormally which divide more rapidly than healthy cells do and continue to accumulate, forming a lump or mass. Cells may metastasize through your breast to your lymph nodes or to other parts of your body.
The cause of genetic mutation is unknown. Some mutations may develop randomly over time, while others are inherited. A complex interaction of your genetic makeup and your environment can be a cause of breast cancer. Hormonal, lifestyle and environmental factors are associated with increased risk of breast cancer. Most breast cancers are diagnosed in women over age 50. But it is not clear why some women get breast cancer even if with no risk factor and others do not. Sometimes those who do have risk factors do not get the disease.

Risk factor of Breast cancer:

Risk factor is something that makes more likely to get breast cancer. But having one or even more breast cancer risk factors doesn't necessarily mean you will develop breast cancer. Many women who develop breast cancer have no known risk factors. Some breast cancer risks may be preventable. However, you cannot control every variable that may influence your risk. Factors that are associated with an increased risk of breast cancer include:

Age and gender:

Women are much more likely than men are to develop breast cancer and the risk increases as you age. The risk begins after age of 40 and is highest for women in their 70s.

Family history:

Having a close blood relative with breast cancer increases your risk of developing the disease. If your mother, sister or daughter was diagnosed with breast cancer, particularly at a young age, you have a increased risk of breast cancer. However, majority of people diagnosed with breast cancer have no family history of the disease. In addition, if you have had breast cancer in one breast, you have an increased risk of developing cancer in the other breast. Also the risk increases if you have had a breast biopsy that found lobular carcinoma in situ (LCIS) or atypical hyperplasia of the breast.

A breast cancer gene mutation:

A very few breast cancers are thought to be inherited. These cases are due to defects in one or more genes, especially the BRCA1 or BRCA2 genes. Having these defective genes doesn't necessarily mean you will get breast cancer, but the risk is greater.

Breast changes and conditions:

Women with dense breasts or with a personal history of breast lumps, a previous breast cancer, or certain non-cancerous breast conditions are at greater risk of developing breast cancer than women who do not have these conditions.


Hormone plays an important role in menstrual cycle of an women in her life time. Women with early menstrual periods, starting before age 12 and late menopause, after age 55 are at greater risk of getting breast cancer. As estrogen stimulates growth of the cells of the breast, longer exposure to the female hormone estrogen may be a factor. Also, use of hormone therapy after menopause can increase the risk of breast cancer. Women who use oral birth control pills have a small increased risk of in breast cancer risk compared with women who never used hormonal contraception. But that risk is temporary as more than 10 years after stopping the pill, breast cancer risk for a woman returns to average.

Pregnancy history:

Having no children or having a first child after age 30 may increase your risk of breast cancer.


Women who are overweight or obese after menopause are more likely to get breast cancer. The exact reason of this is unclear, but it may be due to higher levels of estrogen produced by fat cells after menopause. Being overweight also increases the insulin levels, which may affect breast cancer risk.

Drinking alcohol:

Drinking alcohol increases the risk of breast cancer. The risk rises with greater alcohol intake, and alcohol is known to increase the risk of other cancers too.

Radiation exposure:

The risk of developing breast cancer may be higher than normal for a women if she had chest radiation for another disease as a child or young adult.

Diagnosis of Breast cancer:

The earlier the disease is diagnosed the less the chance of its progression, and the better the outcome with treatment. Although breast cancer can be diagnosed by the above signs and symptoms, screening mammography can detect many of the cancers early before they cause any symptoms.
Different tests and procedures used to diagnose breast cancer include:

Breast exam:

Both of your breasts and lymph nodes in your armpit will be checked physically for feeling of any lumps or other abnormalities.


Screening mammogram is a type of breast X-ray. Mammograms are commonly used to screen for breast cancer. If an abnormality is detected on a screening mammogram, your doctor may recommend a diagnostic mammogram to further evaluate that abnormality.

Breast ultrasound:

Ultrasound uses sound waves to produce images of structures deep within the body. Ultrasound may be used to determine whether a new breast lump is a solid mass or a fluid-filled cyst.


A biopsy is the only definitive way to make a diagnosis of breast cancer where a sample of breast cells for testing will be removed. During a biopsy, your doctor uses a specialized needle device guided by X-ray or another imaging test to extract a core of tissue from the suspicious area. For easy identification of the area of biopsy on future imaging tests, often a small metal marker is left at the site within your breast. To confirm the diagnosis whether the cells are cancerous or non cancerous, biopsy samples are sent to a laboratory for analysis. A biopsy sample is also analyzed to determine the type of cells involved in the breast cancer, the stage of the cancer, and whether the cancer cells have hormone receptors or other receptors that may influence your treatment options.

Breast magnetic resonance imaging (MRI):

An MRI machine uses a magnet and radio waves to create pictures of the interior of your breast. Before a breast MRI, you receive an injection of dye. Unlike other types of imaging tests, an MRI doesn't use radiation to create the images which is one of the reason for considering it safe.
Other tests and procedures may be done depending on your situation.

Staging of Breast cancer:

Once your breast cancer is diagnosed, the stage of your cancer will be determined which will give an idea of what extent it has spread. The stage of cancer helps determine your prognosis and the best treatment options.
Tests and procedures used to stage breast cancer may include:

  • Blood tests, such as a complete blood count
  • Mammogram of the other breast to look for signs of cancer
  • Breast MRI
  • Bone scan
  • Computerized tomography (CT) scan
  • Positron emission tomography (PET) scan

All these test are not required at a time for any patient. Based on your specific circumstances and taking into account new symptoms you may be experiencing, the appropriate tests will be decided by your doctor.
Breast cancer stages range from 0 to IV with 0 indicating cancer that is noninvasive or contained within the milk ducts. Stage IV breast cancer is also called metastatic breast cancer and indicates that the cancer has spread to other areas of the body.
The presence of tumor markers, such as receptors for estrogen, progesterone and HER2 and proliferation factors are also taken in to consideration while staging a cancer.
Until after you undergo breast cancer surgery, complete information about the stage of cancer may not be available. After surgery, a pathologist looks at the cells from the breast cancer as well as from the lymph nodes. As these information tend to be more accurate than the physical exam and X-ray findings alone, it will be used for staging cancer.
TNM staging is a system that uses letters and numbers to describe certain tumor characteristics in a uniform manner. This allows health care providers to stage the cancer which helps determine the most appropriate therapy. This will also aid communication among health care providers.
T: This describes the size of the tumor which is followed by a number from 0 to 4. Higher numbers indicate a larger tumor or greater spread.
TX: Primary tumor cannot be assessed
T0: No evidence of primary tumor
Tis: Carcinoma in situ
T1: Tumor is 2 cm or less across
T2: Tumor is 2 cm to 5 cm
T3: Tumor is more than 5 cm
T4: Tumor of any size growing into the chest wall or skin
N: This describes the spread to lymph node near the breast. It is followed by a number from 0 to 3.
NX: Nearby lymph nodes cannot be assessed  if they have previously been removed
N0: There has been no spread to nearby lymph nodes. In addition to the numbers, this part of the staging also has the designation i+ if the cancer cells are only seen by immunohistochemistry, a special stain and mol+ if the cancer could only be found using PCR, special detection technique to detect cancer at the molecular level.
N1: Cancer has spread to one to three axillary lymph nodes,that could be underarm lymph nodes or tiny amounts of cancer are found in internal mammary lymph nodes (lymph nodes near breastbone).
N2: Cancer has spread to four to nine axillary lymph nodes or the cancer has enlarged the internal mammary lymph nodes.
N3: Any of the conditions below
Cancer has spread to 10 or more axillary lymph nodes with at least one cancer spread larger than 2 mm.
Cancer has spread to lymph nodes under the clavicle with at least area of cancer spread greater than 2 mm.
M: This letter is followed by a 0 or 1, indicating whether the cancer has spread to other organs.
MX: Metastasis cannot be assessed.
M0: No distant spread is found on imaging procedures or by physical exam.
M1: Spread to other organs is present.
Once the T, N, and M categories have been determined, they are combined into staging groups. There are five major staging groups, stage 0 to stage IV, which are subdivided into A and B, or A and B and C, depending on the underlying cancer and the T, N, and M scale.
Cancers with similar stages often require similar treatments.

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