When a person’s particular characteristic or behaviour is associated with an increased risk for a given disease, the characteristic is labelled a “Risk factor”. Eg. Smoking is a risk factor for lung cancer and heart disease.
Some risk factors will influence one’s susceptibility to a particular disease more than others. This is differentiated by relative risk by comparing likelihood of the disease in people with the risk factor compared to people without the risk factor. A relative risk more than 1.0 signifies greater risk while that which is less than 1.0 signifies lower risk.
Relative risk cannot precisely calculate an individual’s risk. If a woman adds a lifetime risk to relative risk, then she will overestimate her risk and if she adds several relative risks together, this will also overestimate her risk.
The purpose is to know your personal risk factor profile and understand what it means so that it will help you and your doctor plan a course of action that may reduce your chance of ever getting the disease or at least to detect it in its earliest, most treatable stages.
Absolute risk is used to give you the likelihood of developing breast cancer. They depend on your age group. The risk of breast cancer increases after age 40. Women younger than 40 are at relatively low risk of breast cancer. Using American Cancer Society information: at 30-39 years, about 1 in 227 (0.44%) can expect to develop breast cancer. In the age range 40-49 years, it is 1 in 68 (1.47%), 50-59 years, it is 1 in 42 (2.38%) and from 60-69 years, it is 1 in 28(3.56%). Overall, a woman has a 1 in 8 chance of developing breast cancer over an 80 year lifespan (about 12%).
If a member of your immediate family, such as your mother or a sister, had breast cancer before menopause, you are at higher risk. To protect yourself, you may want to perform self-breast examination and other screening (mammography) on a more regular basis by the age of 40.
While these statistics may provide a general sense of a woman’s risk at a given age, they cannot be construed to accurately determine a particular woman’s risk, as other variables such as dietary habits, level of activity and family history modify the risk.