• 5 to 10% of breast cancer is hereditary and caused by mutations (changes) in genes.
• Having one or more close relatives (sister, mother, daughter) who have been diagnosed with breast cancer also increases a woman's risk of getting the disease, particularly if more than one relative is affected, and the affected relative(s) were diagnosed at a young age.
• Many of the important risk factors for breast cancer relate to a woman's reproductive history:
  • early onset of periods,
  • late age at first pregnancy,
  • few or no children
  • and late menopause all increase risk, while breast feeding and having children early appear to reduce risk.
• These relationships suggest that oestrogen has an important role in breast cancer, and is supported by the observations that current or recent use of oral contraceptives and hormone replacement therapy (HRT) also increase risk.
• Aspects of lifestyle, that appear to affect the risk of developing breast cancer include:
  • Being overweight or obese increases risk of developing the disease in post- menopausal women.
  • Drinking alcohol raises the risk
  • Higher levels of physical activity are associated with lower risk.

Breast cancer is relatively uncommon before the age of 30, but risk increases with age thereafter, especially up to the menopausal years. Risk continues to rise with age following the menopause, but the rate of increase is less pronounced. One quarter of cases are diagnosed in women under 50, and 36% in women aged 50-64. The remaining 39% are distributed equally between women aged 65-74 and those aged 75 and over.

• The chance of a woman in Ireland developing breast cancer by the age of 64 is 1 in 19 (5.4%)
• The chance of a woman in Ireland developing breast cancer by the age 75 is 1 in 13 (7.9%)
• It is estimated that 2171 new cases will be diagnosed in Ireland in 2006.

For further information:

Breakthrough Breast Cancer (UK) has an excellent booklet: Breast Cancer Risk Factors: The Facts, which lists established, possible and doubtful risk factors. This can be downloaded from the Breakthrough website at www.breakthrough.org.uk

Another reliable source of information is the WCRF/AICR 2nd Expert Report: Food, Nutrition, Physical Activity, and the Prevention of Cancer: a Global Perspective (2007) See at www.aicr.org .

Sources:

Women and Cancer in Ireland, 1994 - 2001, published by the National Cancer Registry of Ireland and the Women's Health Council in February 2006. www.whc.ie www.ncri.ie

National Cancer Registry Ireland.Cancer in Ireland 1995-2005: a summary. 2007 www.ncri.ie