Am I at Risk of Getting Breast Cancer?
The risk of developing breast cancer increases with age; an average European woman aged 25 years has a 1 in 15000 chance of developing breast cancer; for a 40-year old woman the risk is 1 in 200, for a 50-year-old woman the chance is 1 in 50, and at the age of 80 years the chance is 1 in 11.
The number of cases of breast cancer is five times higher in Western countries than in Far Eastern countries such as Japan and China. However, Japanese women who move to the USA increase their risk of developing breast cancer, which shows that the environment also plays an important role.
Risk factors are things that increase your chance of developing breast cancer. The main groups are shown in Table 2.
|1. Cancer history||2. Hormonal||3. Lifestyle||4. Other|
Age when periods started
Obesity after the menopause
Cancer History Risk Factors
Family History of Breast Cancer
It is thought that up to 5% of all breast cancers are inherited owing to the presence of abnormal genes. These genes are passed on from mother to daughter, so having a first-degree relative (such as a sister or mother) with breast cancer will increase your chance of developing the disease. This is particularly true if the relative develops breast cancer in both her breasts, or before she reaches the age of 45 tears. A family history of breast cancer in a first-degree male relative is also associated with a significant increase in breast cancer risk. Breast cancer in a distant relative has little effect on your breast cancer risk.
Your chance of developing breast cancer doubles if one first-degree relative developed the disease before the age of 45 years. If two first-degree relatives developed the disease before the age of 45 years, then your chance of developing breast cancer is four times greater than normal.
Scientists have identified several genes responsible for transmitting breast cancer. Three of the most important of these breast cancer genes are called BRCA-1, BRCA-2 and P53. This inherited form of breast cancer usually develops before the age of 50 years. If a woman has not developed breast cancer by the age of 50 years, despite having a first-degree relative with breast cancer, it is unlikely that she carries the abnormal gene(s).
The BRCA-1 gene is also associated with ovarian cancer. So, the presence of other types of cancer, such cancer of the womb or ovary, in addition to breast cancer, also suggests the possibility that there is a cancer-causing gene in the family. Testing for breast cancer genes is now possible, but may require the presence of living relatives who have had breast cancer, and it may also take a long time to identify the gene.
A significant family history of prostate cancer (early age of onset before the age of 55, more than one relative) is also associated with an increased risk of breast cancer.
Cancer of the Other Breast
This increases the likelihood of breast cancer in the remaining breast.
Hormonal Risk Factors
Starting Periods Before the Age of 11 Years
Women who have a history of starting their periods (menses) before the age of 11 years have a higher chance of developing breast cancer. This is thought to be due to their longer exposure to the female sex hormone oestrogen, which is an established risk factor for breast cancer.
The risk of developing breast cancer increases by 5% for each year of delay in having the first full-term pregnancy. Women who have their first child before the age of 30 years have a lower risk of developing breast cancer than those whose first pregnancy occurs after the age of 35 years. Recent research indicates that breast-feeding also reduces the risk of developing breast cancer.
There is no scientific evidence that pregnancies which end in a spontaneous or induced miscarriage increase the risk of developing breast cancer.
The average age of a woman upon reaching the menopause in western Europe is 50 years. Women who reach the menopause after the age of 53 years have a higher chance of developing breast cancer. Delayed menopause prolongs a women's exposure to oestrogen - just as does starting periods before the age of 11 years.