Breast Cancer

In the breast, there are several different tissues that help it function. These tissues include both dense and fatty tissue, within both are a network of lobes. Within the lobes are small lobules (tube-like structures) that contain milk glands. These lobes, lobules and glands are connected by ducks that bring the milk from the lobes through to the tipple. Throughout the breast, blood vessels and lymph vessels can also be found.

In women, breast cancer has been found to be the most common cancer, when not including skin cancer. Breast cancer in men is somewhat rare, and only accounts for approximately 1% of breast cancer cases.

When otherwise healthy cells begin to grow and change uncontrollably within the breast. This can create a tumour that is either benign or cancerous. If a breast cancer spreads, it will typically go to nearby lymph nodes, however it can also spread to the brain, lungs liver and bones.

Types of Breast Cancer

There are two types of breast cancer: invasive and non-invasive. Invasive cancer has the power to spread from the original tumour site and into the surrounding tissue. 
Non-invasive breast cancer will not spread further than the lobules or the milk ducts within a breast. If a cancer begins in the breast ducts or lobes, they are known as ductal carcinoma or lobular carcinoma. Ductal carcinoma begins the in lining of the milk ducts. This is the most common breast cancer. There are variations on ductal carcinomas. These include ductal carcinomas in situ, which is located solely in the duct, and invasive ductal carcinoma, which is cancer that has spread outside of the duct. Invasive lobular carcinoma begins in the lobules.

Additional types of breast cancer can include:

• Papillary
  
• Metaplastic
  
• Medullary
  
• Mucinous
  
• Inflammatory breast cancer
  
• Paget’s disease
   

Breast Cancer Subtypes

When oncologists study a breast cancer, they identify it from one of three main subtypes. These subtypes allow oncologists to create a treatment plan that can target the specific tumour in question. The three main subtypes include:

• Hormone receptor positive: Receptors are proteins that are found within a cell. When a tumour has estrogen receptors, they are called ER positive. If a tumour has progesterone receptors, it is PR positive. If a cancer produces ER or PR, the cancer is known as hormone receptor positive. This type of cancer often requires these hormones to grow, with approximately 60-70% of breast cancers having either estrogen or progesterone receptors. If a cancer does not have any of the receptors, it is known as hormone receptor negative. Hormone receptor positive cancers often occur in older women who have experienced menopause, however younger women can also get this.

• HER2 positive: Human epidermal growth factor receptor 2 (HER2) is a necessary gene for 10-20% of breast cancer to develop. If this receptor is present, the cancer is known as HER2 positive. This gene makes a protein that is found within cancer cells and often causes a tumour to grow quickly. HER2 cancers can also be hormone receptor positive or negative. If a cancer does not have levels of the HER2 protein or HER2 gene, it is known as HER2 negative.

• Triple negative: Tumours that do not have either ER, PR or HER2 are known as triple negative tumours. This type of cancer accounts for approximately 15-20% of invasive breast cancers and is more prevalent in younger women.

Signs and Symptoms of Breast Cancer

Understanding the symptoms of breast cancer can be an important factor in locating cancer in its early stages. This will lead to a higher success rate of treating the tumour. 

There are several possible symptoms of breast cancer. A patient may experience a range of these, or none at all. There are other reasons that a person may experience these symptoms, so it is important to note that if these symptoms do occur, this does not solely indicate cancer.

It is important to speak with your doctor if you have any of the following:

• A lump in one breast or under the arm. This may feel like a thickening within the tissue or a hard knot.
• A physical change in the breast size or shape
• Physical changes in the nipples
• Nipple discharge that is sudden, bloody or only present within one breast
• Skin irritation
• Swollen and hot breasts with or without a rash
• Persistent breast pain