About 50% of women have no identifiable risk factors. Risk factors include:
AgeThe risk of developing breast cancer increases with age. 70% of breast cancers occur in women above 40 years old.
Family historyHaving a first degree relative (sister, mother, maternal grandmother) who has breast cancer doubles the risk. Women with such a first degree relative should start breast screening early, at about 35 years of age
GenesWomen with BRCA1 and BRCA2 genes have a 40 to 60% lifetime risk of developing breast cancer. However, this forms only 1% of female breast cancer patients.
Reproductive history- Women who have never given birth- Women who had their first child after 35 years old
Menstrual history- Early onset of menses - below 11 years old- Late menopause - above 55 years old
Diet- Alcohol - 2 glasses of alcohol daily increases risk by 1.5 times- Soy products (soya bean) reduces risk of breast cancer- Omega 3 fish oil reduces risk of breast cancer- Vitamin A, C, E and selenium protects against breast cancer
Body weightObesity increases breast cancer risk and increases the body's oestrogen levels
Physical exerciseIt reduces risk of breast cancer and lowers body's oestrogen levels
HormonesHormone Replacement Therapy (HRT) - increases risk of breast cancer by 30% but the risk disappears 3 to 5 years after stopping HRT
Past history of breast cancer increases risk of cancer in opposite breast
Dr Christopher Ng is an obstetrician gynaecologist in private practice.