Breast Cancer

What is Breast Cancer?

Breast cancer begins when cells in the breast start to grow out of control. These cells usually form a tumour, often seen on an X-ray or felt as a lump. The tumour is malignant if the cells can grow into (invade) surrounding tissues or spread (metastasise) to distant body areas. Breast cancer occurs almost entirely in women, but men can get it, too.


How Does Breast Cancer Impact Your Anatomy and Health?

Breast cancer primarily affects the breast tissue, particularly the inner lining of milk ducts or the lobules that supply the ducts with milk. Depending on the spread and stage of the disease, its impact on health and anatomy can vary significantly:

  • Local Effects: Initially, breast cancer may present as a lump or thickening in the breast or underarm. This can alter the physical appearance of the breast, cause changes in skin texture (like dimpling or puckering), or lead to nipple discharge or inversion.
  • Systemic Effects: As cancer progresses, it can cause broader health issues, including severe fatigue, weight loss, and decreased ability to perform daily tasks. The treatment of breast cancer, such as chemotherapy, radiation, and surgery, can also lead to side effects ranging from hair loss and nausea to more significant impacts on heart and bone health.
  • Metastasis: In advanced stages, breast cancer can spread to other parts of the body—typically the bones, liver, lungs, and brain. This spread can significantly impact the function of these organs and is often associated with a poorer prognosis.


Causes and Risk Factors for Breast Cancer

Breast cancer risk is influenced by several factors, with genetics and family history being significant components:

  • Genetic Factors: About 5-10% of breast cancer cases are thought to be hereditary, resulting directly from gene defects (mutations) inherited from a parent. The most common mutations are those of the BRCA1 and BRCA2 genes. Women with these mutations have a higher risk of developing breast cancer and ovarian cancer.
  • Family History: Having a first-degree relative (mother, sister, or daughter) with breast cancer approximately doubles a woman's risk. The risk increases if multiple family members have breast or ovarian cancer, particularly if they were diagnosed at a young age.
  • Hormonal Factors: Hormones, particularly oestrogen and progesterone, play a significant role in breast cancer development. Women who have longer exposure to oestrogen, either through early menstruation before the age of 12, late menopause after age 55, having their first child at an older age, or never having given birth, are at increased risk.
  • Environmental and Lifestyle Factors: These include:
  • Alcohol Consumption: Regular consumption of alcohol appears to increase breast cancer risk.
  • Obesity: Being overweight or obese, especially after menopause, is linked with an increased risk of breast cancer.
  • Radiation Exposure: Exposure to ionising radiation, such as that from X-rays and CT scans, particularly to the chest, increases the risk.
  • Lack of Physical Activity: A sedentary lifestyle is associated with a higher risk of developing breast cancer.
  • Reproductive History: Women who have their first pregnancy after age 30 or who never have a full-term pregnancy have a higher risk of breast cancer.
  • Age: Simply ageing increases the risk of breast cancer, with most breast cancers diagnosed in women over 50 years of age.


Symptoms of Breast Cancer

Common symptoms include:

  • Lump in the Breast or Underarm
  • Change in Size, Shape, or Appearance of a Breast
  • Changes to the Skin Over the Breast
  • Nipple Discharge
  • Nipple Changes
  • Redness or Pitting of the Skin Over Your Breast


Types of Breast Cancer

Breast cancer can manifest in several different forms, each classified based on where the cancer begins, whether it is invasive or non-invasive, and other characteristics of the cancer cells.


Ductal Carcinoma In Situ (DCIS)

DCIS is a non-invasive condition where cells inside the breast ducts have started to turn into cancer cells but haven't spread into the surrounding tissue. It's sometimes referred to as "stage 0" cancer and is highly treatable, but it can increase the risk of developing invasive cancer later.


Invasive Ductal Carcinoma (IDC)

IDC is the most common type of breast cancer, constituting about 70-80% of all breast cancer cases. This cancer starts in the milk ducts and then invades nearby tissue. From there, it can metastasise to other parts of the body.


Invasive Lobular Carcinoma (ILC)

ILC begins in the lobules (glands that produce milk) and can spread to nearby tissues and other parts of the body. It is the second most common type of breast cancer, making up about 10% of all cases.


Lobular Carcinoma In Situ (LCIS)

Though named carcinoma, LCIS (like DCIS) is not a true breast cancer but a marker indicating an increased risk of developing breast cancer later. It occurs when cells in the lobules of the milk glands have abnormal growth.


Triple-Negative Breast Cancer (TNBC)

TNBC lacks three common receptors known to fuel most breast cancer growth—oestrogen, progesterone, and the HER-2/neu gene. This makes it more difficult to treat since most targeted therapies are ineffective against it. TNBC is typically more aggressive and has fewer treatment options.


HER2-Positive Breast Cancer

This type of breast cancer tests positive for a protein called human epidermal growth factor receptor 2 (HER2), which promotes the growth of cancer cells. It tends to be more aggressive than other types but may respond well to treatments targeted against the HER2 protein.


Hormone Receptor-Positive Breast Cancer

This cancer has cells that contain receptors for oestrogen and/or progesterone, which help the cancer grow. Treatments that lower hormone levels or block these receptors can be effective against these cancers.


Inflammatory Breast Cancer (IBC)

IBC is a rare and aggressive form of breast cancer that blocks lymph vessels in the skin of the breast. It is called "inflammatory" because the breast often looks swollen and red or "inflamed."


Paget's Disease of the Nipple

This type of breast cancer starts in the ducts of the nipple, but as it grows, it begins to affect the skin and area of the nipple. It is often associated with underlying breast cancer.


Phyllodes Tumours

These rare tumours grow in the connective tissue of the breast. Most phyllodes tumours are benign, but some are malignant. They tend to grow quickly but rarely spread outside the breast.


Stages of Breast Cancer

Breast cancer stages range from 0 to IV, with each stage indicating the extent of the cancer:

  • Stage 0: Known as ductal carcinoma in situ (DCIS), the cancer cells are confined to the breast ducts and have not invaded surrounding tissue.
  • Stage I: This early stage is divided into IA (tumour up to 2 cm and not spread outside the breast) and IB (small clusters of cancer cells found in lymph nodes).
  • Stage II: Divided into IIA (tumour between 2 cm and 5 cm or cancer has spread to 1-3 nearby lymph nodes) and IIB (tumour larger than 5 cm or smaller tumour with more extensive spread to lymph nodes).
  • Stage III: Known as locally advanced cancer, this stage is divided into IIIA (cancer has spread to 4-9 lymph nodes or has enlarged the internal mammary lymph nodes), IIIB (tumour of any size that has invaded chest wall or skin with up to 9 lymph nodes involved), and IIIC (cancer found in 10 or more axillary lymph nodes, nodes near the collarbone, or internal mammary nodes).
  • Stage IV: Cancer has spread to other body parts, such as the bones, lungs, liver, or brain. This stage is also known as metastatic breast cancer.


Breast Cancer Diagnosis

Breast cancer diagnosis typically involves several steps:

  • Physical Examination: Checking both breasts and lymph nodes in the armpit for lumps or other changes.
  • Mammography: X-ray of the breast used as a screening tool or for further investigation if an anomaly is suspected.
  • Ultrasound: Used to distinguish between solid tumours and fluid-filled cysts.
  • MRI: Provides detailed images of the breast and is often used for women with a higher risk of breast cancer.
  • Biopsy: The definitive way to diagnose breast cancer involving the removal of cells or tissues for examination under a microscope.


Breast Cancer Treatments

  • Surgery: Options include lumpectomy (removing the tumour and some surrounding tissue) or mastectomy (removing one or both breasts entirely).
  • Radiation Therapy: Uses high-energy waves to target and kill cancer cells.
  • Chemotherapy: Involves drugs to kill cancer cells, often used when cancer is considered aggressive or has spread.
  • Hormone Therapy: For cancers that are hormone receptor-positive, medications can help block the body's natural hormones (oestrogen and progesterone) that fuel cancer growth.
  • Targeted Therapy: Drugs or other substances that block cancer growth by interfering with specific molecules involved in tumour growth and progression.
  • Immunotherapy: Employs the body’s immune system to fight cancer.


What if Breast Cancer is Untreated?

If breast cancer is not treated, it can continue to grow and spread to other parts of the body, a process known as metastasis, which can be life-threatening. The cancer might also invade and damage surrounding tissues and organs. Pain, functional impairments, and significant health problems can occur as the cancer advances. Ultimately, untreated breast cancer can be fatal.

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