Risk Factors That You Cannot Change

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Being female
Simply being a woman is a main risk factor for developing breast cancer. Women have more glandular tissues than men and their breast cells are constantly exposed to oestrogen. Men too can develop breast cancer, but it is about 100 times more common among women than men.

Increasing age
Age alone does not cause cancer, but the incidence of breast cancer increases the older you get. About 64% of breast cancer diagnoses are among women aged 40 and above. It may be that initial damage to cells took place years earlier, and that the cancer took time to develop.

Number of menstrual cycles (menarche and late menopause)
The total number of menstrual cycles in your life affects your exposure to oestrogen. If you started menstruating (menarche) at an early age (before age 12) and your menopause occurs at a late age (after age 55), the overall number of years of exposure to oestrogen is higher – hence, increases the risk of breast cancer, than for women who have a later first period and earlier menopause.

Race
Chinese women are slightly more likely to develop breast cancer than Indians or Malay women, with an incidence rate of 59.7 per 100,000 women for Chinese, 55.8 per 100,000 women for Indians and 33.9 per 100,000 women for Malays. However, Malay women are more likely to die of this cancer because they are often diagnosed at an advanced stage when breast cancer is harder to treat and cure.

Other studies have shown that white women are more likely to develop breast cancer.

Family history of breast cancer (genetic risk)
Breast cancer risk is higher among women whose close blood relatives have this disease. Having one first-degree relative (mother, sister, daughter) with breast cancer approximately doubles a woman’s risk, compared to someone with no family history of breast cancer. The risk of developing breast cancer is increased if:

* You have 2 or more relatives with breast or ovarian cancer. * Breast cancer occurs in a relative (mother, sister, grandmother or aunt) younger than 50 years old on either side of the family. The risk is higher if your mother or sister has a history of breast cancer. * You have relatives with both breast and ovarian cancer. * You have 1 or more relatives with 2 cancers (breast and ovarian, or two different breast cancers). * You have male relatives with breast cancer. Breast cancer genes, BRCA1 and BRCA2 indicate that a woman has about 80% chance of developing breast cancer and a 50% chance of passing the gene on to her daughters. Women with these inherited mutations also have an increased risk for developing ovarian cancer.

Recent studies have shown that about 5% to 10% of breast cancer cases are hereditary as a result of gene changes (mutations). Normally, these genes help prevent cancer by making proteins that keep cells from growing abnormally. However, if you have inherited either changed gene from a parent, you are at increased risk for breast cancer.

Other genes discovered that might also lead to inherited breast cancer include the ATM gene. ATM stands for ataxia-telangiectasia mutation. The gene is responsible for repairing damaged DNA. Certain families with a high rate of breast cancer have been found to have mutations of this gene. Another gene, the CHEK-2 gene, also increases breast cancer risk when it is mutated.

Inherited mutations of the p53 tumor suppressor gene can also increase your risk of developing breast cancer, as well as leukemia, brain tumors, and/or sarcomas (cancer of bones or connective tissue). The Li-Fraumeni syndrome, named after the 2 researchers who described this inherited cancer syndrome, is a rare cause of breast cancer.

If you are considering genetic testing, it is strongly recommend that first you talk to a genetic counselor, nurse, or doctor qualified to interpret and explain these tests before being tested. It is very important to understand and carefully weigh the benefits and risks of genetic testing before these tests are done. Testing is expensive and is not covered by some health plans. There is concern that people with abnormal genetic test results will not be able to get life insurance or that coverage may only be available at a much higher cost.

Personal history of breast cancer
A woman with cancer in one breast has a 3- to 4-fold increased risk of developing a new cancer in the other breast. This is different from a recurrence of the first cancer.

Previous abnormal breast biopsy
Lumps in the breast are very common. Most non-cancerous lumps in younger women are caused by benign tumour called fibroadenomas. In older women, non-cancerous lumps are probably caused by cysts. Neither fibroadenomas nor cysts (without proliferative breast disease) pose any risk to health and do not increase the chance of getting breast cancer.

However, if a benign breast lump shows certain changes – atypical hyperplasia, there might be a slightly increased chance of developing breast cancer, even though that particular lump has been removed. An atypical hyperplasia (ductal or lobular) increases a woman’s breast cancer risk by 4 to 5 times. Experts believe that atypical hyperplasia is a sign that the cells in the breast are generally unstable, hence there is greater chance of developing breast cancer at a later stage.

Women whose earlier breast biopsies detected any of the changes below also have a slightly higher risk of breast cancer (1.5 to 2 times greater than other women):

  1. fibroadenoma with complex features
  2. hyperplasia without atypia
  3. sclerosing adenosis
  4. solitary papilloma

Previous breast radiation
Women who as children or young adults have had radiation therapy to the chest area as treatment for another cancer (such as Hodgkin disease or non-Hodgkin lymphoma) are at significantly increased risk for breast cancer. Some reports found the risk to be 12 times normal risk. This varies with the age of the patient at the time of radiation. Younger patients have a higher risk. If chemotherapy was also given, the risk may be lowered if the chemotherapy stopped ovarian hormone production.