Many women in London agonise over the questions; am I at risk of getting breast cancer, what are my chances of getting breast cancer? Professor Kefah Mokbel, Consultant Breast Surgeon at St. George’s and The Princess Grace Hospitals in London has written extensively about the topic.
The risk of developing breast cancer increases significantly with age; an average European woman aged 25 years has a 1 in 15000 chance of developing breast cancer; for a 50-year-old woman the chance is 1 in 50, and at the age of 80 years the chance is 1 in 11.
It is thought that up to 5% of all breast cancers are inherited due to the presence of abnormal genes passed on from mother to daughter. Having a first-degree relative (such as a sister or mother) with breast cancer will increase your chance of developing the disease.
A significant family history of prostate cancer is also associated with an increased risk of breast cancer.
Hormonal Risk Factors
Starting Periods before the Age of 11 Years
Women who have a history of starting their periods before the age of 11 years have a higher chance of developing breast cancer. This is thought to be due to their longer exposure to the female sex hormone oestrogen, which is an established risk factor for breast cancer.
The risk of developing breast cancer increases by 5% for each year of delay in having the first full-term pregnancy. Women who have their first child before the age of 30 years have a lower risk of developing breast cancer than those whose first pregnancy occurs after the age of 35 years. Recent research indicates that breast-feeding also reduces the risk of developing breast cancer.
The average age of a woman upon reaching the menopause in Western Europe is 50 years. Women who reach the menopause after the age of 53 years have a higher chance of developing breast cancer. Delayed menopause prolongs a women’s exposure to oestrogen – in the same way as starting periods before the age of 11 years.
The Oral Contraceptive Pill
Taking an oral contraceptive pill which contains oestrogen within the previous 10 years slightly increases the chance of developing breast cancer. However, breast cancer that develops in contraceptive pill users seems to be less advanced than in non-users.
Hormone Replacement Therapy (HRT)
Taking HRT after the menopause seems to increase the risk of developing breast cancer, especially if it is continued for more than 10 years. HRT, however, reduces the risk of brittle-bone disease (osteoporosis), bone fractures and large bowel cancer. It also improves the symptoms of the menopause, such as vaginal dryness, hot flushes and depression. It is currently thought that HRT should be avoided where possible in women with a personal or a significant family history of breast cancer.
Lifestyle Risk Factors
Obesity after the menopause increases the risk of breast cancer in women. In post-menopausal women the body fat is the main source of oestrogen production; so obese women will have more oestrogen on board, thus increasing their breast cancer risk.
It is thought that a high intake of saturated animal fats and red meat (especially if overcooked) increases the risk of developing breast cancer.
Recent evidence suggests that excessive alcohol intake increases the likelihood of breast cancer. The risk seems to increase with all types of alcoholic drinks.
There is increasing evidence that both active and passive smoking increase the risk of breast cancer especially in women younger than 50 years.
Other Risk Factors
Previous Benign Breast Biopsy
The presence of certain microscopic features in a breast biopsy is associated with a higher risk. For example, the risk is increased by 4-5 times if a condition known as atypical epithelial hyperplasia is found in the breast biopsy.
Mammographic density in 75% or more of the breast is associated with an almost fivefold increased risk of breast cancer, and this risk persists for an extended period of time. In addition, for women with extensively dense breasts, the masking effect of dense breast tissue increases the odds more than 17 times of a cancer being missed and then detected by non-screening methods. In such cases the addition of ultrasound scan and MRI imaging to digital mammography should be considered.