Breast cancer is one of the top two cancers in women and one of the top causes of cancer- related deaths in women worldwide. Understanding the risk factors for breast cancer permits us to identify women at increased risk and to intervene to modify this risk, both individually and in society.
Approximately 230 000 new cases of invasive breast cancer are expected to be diagnosed in the United States in 2012, and almost 40 000 will die from the disease. The lifetime risk of developing breast cancer is one in six. These statistics make it very important for women (and men) to understand the risk factors relating to breast cancer in order to be able to modify those risk factors they can, and to take screening for cancer very seriously.
Risk factors:
Age and Gender – These are among the strongest risk factors. Breast cancer is 100 times more likely to occur in women than in men. The incidence rates also rise sharply with age until the age of 50, whereafter the incidence stabilises.
Personal History – A personal history of breast cancer increases your risk of developing cancer in the same or opposite breast.
Family History – A family history of breast cancer in a first degree relative. The younger the relative at age of diagnosis, the greater the risk.
Hormone replacement therapy Long-term exogenous oestrogen ingestion in the form of hormone replacement therapy has been consistently associated with an increased risk of developing breast cancer. Current guidelines suggest that HRT should not be taken for longer than five years.
Lifestyle – Both active and passive smoking have been strongly linked to the risk of developing breast cancer.
Dietary factors are more problematic to associate with breast cancer, as numerous studies have shown mixed results when trying to associate certain dietary factors with breast cancer risk. However a healthy balanced diet is believed to improve the risk. Exercise has been consistently associated with a reduced risk of breast cancer.
Reproductive factors – An early age of onset of menstrual cycle as well as late menopause are strong risk factors for developing breast cancer. This is thought to be due to an increased lifetime exposure to oestrogen. Child birth also plays a role in that women who never give birth have a greater risk of developing breast cancer. So too do women who have their first child after the age of 30. The reasons for the protective effect of pregnancy are still poorly understood, but it is assumed to be related to hormonal factors.
Exposure to Radiation – Women who have been exposed to radiation of the chest at an early age are at increased risk of developing breast cancer. This occurs most commonly in treatment of lymphomas or other cancers at a young age, but also survivors of nuclear accidents.
Genetic Mutations – Mutations in the BRCA genes, as well as other specific genes are well known to increase the risk of developing breast cancer, but these are surprisingly rare, even in familial breast cancer. This should only be tested once fully discussed with your doctor, as these tests can have some dramatic implications.
Unfortunately, many of the risk factors for breast cancer are unable to be modified and as such screening for breast cancer is an exceptionally important tool in preventing cancer related death. However, certain risk factors are under the control of each and every woman and thus she can play an active role in prevention. Adjusting your lifestyle is foremost among these steps.
Regular screening for breast cancer has remained the most important weapon in a woman and her doctors armoury. Every woman should perform self-breast examination as regularly as possible. Self-breast examination has saved countless women’s lives by detecting a lump or change in the breast early.
Screening mammogram and ultrasound remain the most important investigation available to doctors and all women, to detect any abnormalities early as well as to investigate any suspicious lumps in the breast.
The screening mammogram is widely available, extremely cost effective and has been proven countless times to improve the outcome of breast cancer. All women should start screening mammography from the age of forty.
Written by Dr Owen Nosworthy