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About Breast Cancer
What is Breast Cancer?
In order to properly treat and one day cure breast cancer, it is important to understand what breast cancer really is. In short, breast cancer is a disease that affects the cells of the breast. Breasts, like the rest of the body, are made up of millions of cells. When the body is attacked by cancer, cells will grow abnormally and either circulate in the blood or immune system, or form lumps and tumors.
When these abnormal cells grow, they can form lumps in the body that are either benign or malignant. Benign growths will grow to a certain size, but will not spread to other parts of the body, and they are not usually life-threatening. Malignant (cancerous) tumors do not stop growing when they reach a certain size, and can pose serious danger to the body. They can attack surrounding tissues and possibly spread to other parts of the body where they will metastasize, or create new tumors. It is the process of metastatic growth in other areas of the body that is the most harmful.
The majority of breast cancers start in the glandular tissue of the breast, called adenocarcinoma, and the most common form of breast cancer is ductal carcinoma, which is in the milk ducts of the breast. While ductal carcinoma breast cancer is the most common, there are also other types of breast cancers that affect the body in different ways, such as inflammatory breast cancer.
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Stages of Breast Cancer
Breast cancer is staged according to its development in the body. After the healthcare team reviews the tumor’s details, such as size, characteristics, and whether it has spread to other areas of the body, they are able to determine the nature of the illness, as well as the available treatment options. Staging provides information on risk of recurrence and the best course of action in treating the cancer.
There are two methods used in staging breast cancer, the Stage 0 to IV method, and the TNM method (Tumor Node Metastasis). In the Stage 0 to IV method, breast cancer is divided into groups depending on the size of the tumor, and whether it has spread to other parts of the body. The more serious the cancer, the higher the stage number will be.
When using the TNM method, each of the letters is followed by a number describing the size of the tumor, and the extent to which other parts of the body are affected. These numbers can range from 1-4 depending on the severity of the cancer, and whether it has spread to other parts of the body.
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What Causes Breast Cancer?
There is no one thing that causes breast cancer, but there are some common factors that seem to increase the risk of developing it. One of the most common risk factors of being diagnosed with breast cancer is being a female. As a woman or man ages, the incidence of breast cancer increases.
Family history also plays a role in whether an individual will develop breast cancer. If any immediate family members have been diagnosed with breast cancer before menopause, there may be a higher risk of developing the disease. There are also two genes that are associated with breast cancer: BRCA1 and BRCA2. These two genes are associated with about 5-10% of all breast cancer cases, and women who test positive for one of these genes may have a higher risk of developing breast or ovarian cancer. BRCA2 is associated with male breast cancer. It is possible to be tested for these genes.
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Here is a table listing the different categories of known risk factors:
Risk Factors Associated with Breast Cancer by Level of Risk
Weak risk factors for breast cancer
- Family history of postmenopausal breast cancer, except if associated with malebreast cancer + bilateral disease
- High Socioeconomic status
- Nulliparity
- Later age at first birth (30 yr vs 20 yr)
- Later age at menopause (55 yr vs 45 yr)
- Early age at menarche (11 yr vs 15 yr)
- Postmenopausal obesity
- Alcohol consumption
- Diet
- Hormone replacement therapy (long term usage)
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Moderate risk factors for breast cancer
- Older age
- North American and Northern European residence
- Family history of premenopausal breast cancer
- Personal history of breast cancer
- Breast hyperplasia without atypia
- Mammographic density occupying 50% of the breast volume
Strong risk factors for breast cancer
- Family history of premenopausal bilateral breast cancer or premenopausal breast cancer in mother, grandmother, sister, daughter and aunt or breast cancer and ovarian cancer in mother, grandmother, sister, aunt
- Evidence of susceptibility gene BRCA1/BRCA2
- Personal history of lobular carcinoma in situ
- Breast atypical hyperplasia
- Mammographic density occupying 75% of the breast volume
Reference:
1. (BC Med J 1997;39:496-500)
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Definitions to some common breast cancer related terms:
Benign growth: A non-cancerous lump or growth.
Biopsy: Removal of tissue sample for examination.
Carcinoma in situ: Ductal carcinoma in situ (DCIS) and lobular carcinoma in situ (LCIS). Both are non-invasive or non-spreading tumors. They are sometimes referred to as “pre-cancer.”
Chemotherapy: A term for systemic drugs usually given by intravenous injection that are used to kill cancer cells.
Cyst: A fluid-filled sac, usually benign.
Lymph nodes: Glands that are part of the body’s defense system against infection.
Malignant growth: A tumor growth that can spread somewhere else in the body (i.e. cancer).
Mammogram: A low-dose x-ray used to get a better look at changes found in the breast through physical examination, or to check the breast even when no obvious changes have been discovered.
Mastectomy: Removal of the whole breast.
Metastatic: Cancer that has spread through the blood vessels or lymphatic channels to distant sites in the body.
Radiation: Ionizing radiation used to kill tumor cells.
Remission: The absence of any detectable signs of a tumor after treatment has been completed.
Staging: A system for looking at a tumor to determine extent and risk of spread or recurrence, and appropriate treatment choices.
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