Risk factors of Breast Cancer

Risk Factors which cannot be Changed

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The Risk Factors for Breast Cancer are many, but having one or more risk factors does not always mean that a woman will get breast cancer.

Many factors can influence these risk factors. Very often, it is seen that a woman with a number of risk factors do not get breast cancer while a woman with no apparent risk factor may suffer from it.

Even when a woman with breast cancer does have a risk factor, it is very difficult, if not impossible, to prove that her cancer is indeed a result of that particular risk factor.

Some risk factors can be changed - for example obesity and alcohol intake. But some cannot be changed, such as those that are familial or genetic. But others

Risk Factors Which Cannot be Changed

  • Age: A woman's risk of breast cancer increases as she ages. While women less than 30 years account for only 0.3% of breast cancer cases, about 77% of women with breast cancer are over age 50 at the time of diagnosis. The following chart (from National Cancer Institute, www.cancer.gov, 2004) gives the increase in risks as a woman ages.

     A Woman's Chances of Breast Cancer Increases With Age 
    From age 30 to age 39 0.44% (1 in 227)
    From age 40 to age 49 1.49% (1 in 67)
    From age 50 to age 59 2.79% (1 in 36)
    From age 60 to age 70 3.38% (1 in 26)

  • Gender: Although nearly 2,000 men will be diagnosed with breast cancer each year, breast cancer is 100 times more common in women.
  • Genetics: Recent research has shown that women who carry certain genes are more likely to develop breast cancer. These changes, or more specifically, mutations of these genes, are responsible for more than 10% of all breast cancerrs.

    • BRCA1 / BRCA2 Genes: Women who carry mutations of BRCA1 (breast cancer gene 1) or BRCA2 (breast cancer gene 2) are at higher risk of developing both breast and ovarian cancer than women who do not have these genetic mutations.

    • HER2 Gene: The HER2 (human epidermal growth factor receptor 2) is another gene which has been found to increase the risks of developing breast cancer. This gene is found on the surface of cells that plays a key role in regulating cell growth. When mutations of this gene occurs, extra HER2 recptors are formed in the breasts and ovaries, increasing the risk of developing cancers in these two organs. The drug, Herceptin, is the drug of choice used in the treatment of HER2 positive breast cancers.

    • p53 Gene: Mutations of the p53 gene may not only increase the risks of developing breast cancer but also causes a more aggressive form of breast cancer in which the outcome is poorer than in other types of breast cancers.

    • ATM Gene: The ATM gene normally helps repair damaged DNA. Mutations can increase the risks of breast cancer.

    • CHEK2 Gene: Risks of breast cancer doubles in women who have a mutated form of this gene.

    • PTEN Gene: Mutations of this gene are usually inherited. Women who have this mutated gene are at increased risk for both benign and malignant breast tumors. They may also have growths in the digestive tract, thyroid, uterus, and ovaries.

  • Menstrual Periods: The risks of breast cancer increases in women who have their first menstrual period before the age of 12 years or who get their menopause late, after the age of 55 years. It is believed that this is due to prolonged exposure to estrogen of the reproductive organs as well as other organs like the breast which have estrogen receptors.

    Risk factors for breast cancer which cannot be prevented

  • Family History: A woman with a family history of breast cancer are at a much more higher risk than other women. A woman with a first degree relative (mother, sister, daughter) with breast cancer can have double the risk of other women.The following conditions increase breast cancer risk (From : American Cancer Society, www.cancer.org, 2004)

    • Two or more relatives with breast or ovarian cancer.
    • Breast cancer occurs before age 50 in a relative (mother, sister, grandmother or aunt) on either side of the family. The risk is higher if the mother or sister has a history of breast cancer.
    • Relatives with both breast and ovarian cancer
    • One or more relatives with two cancers (breast and ovarian, or two different breast cancers)
    • A male relative (or relatives) with breast cancer
    • A family history of breast or ovarian cancer and Ashkenazi Jewish heritage.
    • A family history includes a history of diseases associated with hereditary breast cancer such as Li-Fraumeni or Cowdens Syndromes.
  • Personal History: A woman who has had any type of breast cancer in one breast runs a 3-4 times greater risk of the other breast getting cancer.

  • Previous Benign Breast Diseases: Women who have had a previous benign condition or a pre-cancerous condition in a breast has a higher risk of getting cancer in the same breast. The benign conditions include:

    • Lobular carcinoma in Situ(LCIS) Although technically, LCIS is a cancer since the cells are abnormal, it is usually considered a precancerous condition since the abnormal cells do not always spread beyond the breast lobule if not treated.
    • Atypical Ductal Hyperplasia (ADH)
    • Atypical Lobular Hyperplasia(ALH)
    • Complex fibroadenoma or Phyllodes tumor
    • Sclerosing adenosis
    • Dense breasts as seen on mammography

  • Race and Ethnicity: White women have a slightly higher risk of getting breast cancer but black women get more aggressive breast cancers and are more at risk of dying from it if they do get breast cancer. Asian and Hispanic women have a lesser risk of getting breast cancer.

  • Previous Radiation Therapy: Women who have received radiotherapy to the chest due to any cancers, especially Hodgkin's disease are at a higher risk of developing breast cancer.

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