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Understanding Breast Cancer Risk
Every woman is at some risk for developing breast cancer during her lifetime, but the risk level varies from one individual to the next depending on what are known as risk factors – anything that increases the chances of developing a disease. For breast cancer, a number of lifestyle, biological, and genetic risk factors have been identified. Understanding what risk factors (if any) you carry can be important, because there are steps that can be taken either to reduce your breast cancer risk, or to increase the likelihood that if breast cancer develops it will be detected at an early, curable stage.
While a single risk factor is unlikely to cause a cancer to develop, several risk factors interacting with one another may contribute to the process. It is important to note, however, that having multiple risk factors for breast cancer does not necessarily mean you will develop the disease. At the same time, a woman without risk factors can still get breast cancer. In fact, most women diagnosed with breast cancer have few or no apparent risk factors; thus, it is important for all women to follow basic guidelines for early detection and screening. In addition, because risk levels vary with each individual, strategies for reducing risk that are appropriate for one woman to consider may not be appropriate for another.
Next to skin cancer, breast cancer is the most frequently diagnosed cancer for women in the United States: The chance of a woman in this country developing breast cancer during her lifetime is approximately one in eight. While the causes of breast cancer are not completely understood, a number of risk factors have been identified. The biggest ones are being female and aging.
Women are much more likely to develop breast cancer than men, who account for less than 1% of all new breast cancer cases diagnosed each year. And, while the average woman’s lifetime risk of developing breast cancer is about 12%, this risk varies with age. For women under the age of 40 it is low – less than 1% within the next 10 years. However, the breast cancer risk increases through the life course and is highest for women in their 60s and 70s.
The likelihood of developing breast cancer within the next 10 years, by age:*
|Age 20||0.6%||1 in 1,1760|
|Age 30||0.44%||1 in 229|
|Age 40||1.44%||1 in 69|
|Age 50||2.39%||1 in 42|
|Age 60||3.40%||1 in 29|
|Age 70||3.73%||1 in 27|
*From American Cancer Society Breast Cancer Facts & Figures 2009-2010.
May Be at Increased Risk
You may be at increased risk of developing breast cancer if you have one or more known breast cancer risk factors. Being at increased risk, however, doesn’t mean you will develop breast cancer. In addition, there may be steps you can take to lower your breast cancer risk
Certain individuals are considered to be at increased risk for breast cancer compared to the general population. A woman with a history of cancer in one breast, for example, is at 3-4 times the risk of developing a new cancer in the other breast or in another part of the same breast as her original cancer. (This is different from a recurrence of the previous breast cancer.) Individuals who have inherited mutations in the BRCA1 and BRCA2 genes are at even greater risk.
The combination of several modest breast cancer risk factors such as family history and reproductive history can raise a woman’s lifetime breast cancer risk above 20% – the threshold for being classified as being at increased risk. This classification, however, does not necessarily mean you will develop breast cancer. Women who are at increased risk will often be invited to participate in more intensive breast cancer screening programs, take steps to lower breast cancer risk, and/or undergo preventive surgery to reduce their risk as much as possible.