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Good to know
- Cancer means there's a growth that's not under normal control of the body. The cells replicate faster than usual and don't adhere together normally. This means the cells can invade local structures and the blood stream/lymphatic system.
- Breast cancer occurs when abnormal cells form a mass of extra tissue (a tumour) in the breast.
- Breast cancer is a general term for different types of cancer that occur in the breast.
- The disease can be discovered by examination of the breasts, mammography, ultrasound testing and/or biopsy.
- Treatment depends on the stage and type of the cancer, as well as your age and health.
- The two main categories of breast cancer are lobular and ductal carcinomas. Each has subtypes, which differ in their potential to spread to other body tissues. Treatment of breast cancer involves local and systemic treatment. Different specialists should be involved to optimise the treatment regime.
The disease
Breast cancer is a general term for different types of cancer that develop from breast tissue cells. When abnormal cells divide in an uncontrolled manner, they can form a mass of extra tissue, or tumour, which can be benign or malignant. Benign tumour cells don't spread to other parts of the body, can usually be removed and don't recur. Malignant (cancerous) tumour cells can invade nearby tissues and break away from the primary tumour to form secondary tumours (metastases) elsewhere in the body.
The breast and lymph nodes
The breast contains 15 to 20 sections, or lobes. Each lobe has smaller lobules or glands. Ducts transport milk from the glands to the nipple. Stroma (fatty tissue and ligaments) surrounds the ducts and lobules. The breast is supplied with blood and lymph vessels. Lymph vessels carry tissue fluid, or lymph, which contains immune system cells. Lymph vessels lead to small glands, called lymph nodes (collections of immune system cells). Lymph node clusters draining from the breast occur under the arm, above the collarbone, in the chest and elsewhere in the body. Most cancers begin in ducts or lobules; occasionally, tumours form in non-glandular tissue. Breast tissue fluid drains into underarm lymph nodes, which filter lymph and may form a barrier against cancer cells. Cancer cells may spread to the lymph nodes or may spread around the body to other organs via the blood system. Usually, the lymph nodes are affected first; then the organs most likely to be affected are the lungs, liver, bone and brain. Once the cancer has spread to the axillary (underarm) lymph nodes, it's likely to have spread in the bloodstream to other organs.
Types of breast cancer
Breast cancer is also categorised as invasive (infiltrating) or non-invasive (in situ). Invasive cancer can grow directly into other parts of the body, or travel in blood or lymph. Non-invasive cancers may become invasive, but usually don't spread, unless they have an invasive component. Invasive cancers may exist with non-invasive cancers. The cancer can be localised or multifocal. Occasionally, more than one primary tumour may be present at the same time.
Common types of breast cancer:
- Infiltrating/Invasive Ductal Carcinoma (IDC) comprises 65 to 85 percent of cases. It begins in milk duct cells and can break through duct walls to invade fatty tissue. It can metastasize (spread) via blood or lymph. On a mammogram, it's usually revealed as an irregular mass, microcalcifications or both. It may appear as a lump, which usually feels harder than a benign lump.
- Infiltrating/Invasive Lobular Carcinoma (ILC) accounts for about 10 percent of cases. It originates in milk-producing lobes, and can spread to fatty tissue and elsewhere in the body. On a mammogram, it may appear similar to IDC, but physical examination doesn't usually reveal a hard mass – rather a vague thickening of tissue. It can occur in more than one place in the breast (multicentric/multifocal), or in both breasts simultaneously (bilateral).
- Three slow-growing invasive subtypes are Medullary, Mucinous and Tubular Carcinomas, together representing about 12 percent of cases. They have a better prognosis than other more common invasive cancers.
- Inflammatory Carcinomais an IDC subtype. Typically the breast becomes red, swollen and warm, and the skin thickens and may develop small bumps. This is due to rapid cancerous growth which blocks lymph vessels. In 90 percent of cases, cancer has spread to the lymph nodes at diagnosis. Prognosis is poor: this cancer is aggressive and is generally treated with chemotherapy. Inflammatory cancer accounts for about four percent of cases.
- Paget's Disease starts in milk ducts and can spread to the nipple and areola, causing crusting and scaling. There's usually a history of nipple inflammation or discomfort. It may be associated with in situ or infiltrating carcinoma. If no lump can be felt, and a biopsy shows no invasive cancer, prognosis is good. The treatment is similar to invasive cancers.
- Soft tissue tumours: Tumours may originate in the supportive tissue of the breast. These tumours are uncommon and tend to have a good outcome.
