Related topics
Related topics
Menstrual / Reproductive history
Risk factors for the development of breast cancer
Abnormal mammogram
Mammography is used for screening of women for breast disease and as part of the triple assessment* of women with a discrete lesion.
Any woman found to have an abnormality on screening is either recalled for further radiological examination or referred to a breast unit for further investigation.
5-15% of patients with breast cancer have no mammographic abnormality. Currently two view mammography is used for first visit screening.
Two view mammography has been found to yield a higher detection rate and is expected to become part of the National Screening Protocol soon, especially in the diagnosis of small (non-palpable) invasive cancers.
Mammograms can be used to localise non-palpable lesions with fine flexible guide wires. Asymptomatic women under the age of 40 should not be offered routine mammography.
* See section on "Triple Assessment" (Investigations Radiology -section)
Family history
Approximately 5-10% of breast cancer, in Western countries, is due to genetic predisposition.
Several genes appear to be involved including BRCA1, BRCA2 and p53. Inherited breast cancer seems to be associated with other cancers including ovarian, colonic and prostatic.
Women carrying a genetic mutation, which predisposes them to breast cancer, tend to develop bilateral disease or develop the disease at an early age.
A woman's risk of breast cancer is significantly increased if she has a first degree relative who developed breast cancer before the age of 40.
The younger the age of the relative developing the disease, the greater the risk. The risk increases dramatically, if two first degree relatives develop breast cancer.
Patients with two first degree relatives having been diagnosed with breast cancer below the age of 50, or three below 60 years, should be referred to a Family History clinic, if available.
Hot flushes
Hot flushes are a common vasomotor complaint of the menopause but may also be experienced by pre-menopausal women.
They are caused by declining oestrogen levels. Hot flushes are often associated with chemical or surgical ovarian ablation in pre-menopausal women.
Hot flushes are commonly experienced by post-menopausal women taking hormone treatment as therapy for advanced disease or in the adjuvant setting.
Menopause and HRT
Women who have a late natural menopause have a higher risk of breast cancer.The use of HRT and the risk of breast cancer is currently being debated.
There is a view that the use of HRT should be limited to 5 - 8 years. There is a small increased risk of breast cancer associated with HRT (approximately 1.3 x after 10 years treatment), but there are other health issues (e.g. osteoporosis , reduction in heart disease mortality) which may outweigh the disadvantages of HRT in terms of the increased risk of developing breast cancer.
Breast density can increase when taking HRT, which can make mammographic interpretation more difficult. Hormone-induced symptoms such as breast pain and cysts may occur.
The use of HRT in patients who have breast cancer is a controversial issue and should be discussed with the Breast Unit.
Menstrual / Reproductive history
Nulliparous, or women who have their first child after the age of 30, have an increased risk of breast cancer.
The risk is even greater in women who have their first child after 35 years of age (relative risk 3x). There appears to be a reduced risk of breast cancer in women who have their first child before the age of 20.
Women who have an early menarche or who have a late menopause, have an increased risk of developing breast cancer (relative risk 3x). There is a reduced risk of breast cancer in women who have had a bilateral oophorectomy or a natural early menopause prior to the age of 40.
Prolonged use of the combined oral contraceptive pill is associated with a slightly increased risk (relative risk 2x for >4 yr. use while young), particularly if the higher oestrogen pills were prescribed. In current users, the risk falls back to normal after 5 years cessation. Use of the contraceptive pill in women over the age of 40 slightly increases the risk of breast cancer.
Non-hormonal methods of contraception i.e. barrier methods or intra-uterine devices, are not associated with an increased risk of breast cancer.
Risk factors for the development of breast cancer
Genetic factors appear to account for no more than 10% of breast cancers in Western women.
The cause of the majority of breast cancer is unknown but a number of characteristics are identified as probable risk factors for breast cancer.
These are listed as single factors in descending order of importance.
However, it is important to consider that in few instances will only one factor prevail.
| Factor | Relative risk at extremes |
| Age | >10 |
| Geographical location (western countries) | 5 |
| Previous benign disease (atypical hyperplasia) | 4-5 |
| Cancer in contralateral breast | >4 |
| Early menarche | 3 |
| Late age at first pregnancy | 3 |
| Exposure to ionising radiation | 3 |
| Family history | >2 up to >10 |
| Oral contraceptives (>4 yr. while young) | 2 |
| High socio-economic group | (1&2) 2 |
| High body weight (post-menopausal) | 2 |
| High saturated fat diet | 1.5 |
| HRT (> 10 years use) | 1.5 |
| High alcohol consumption | 1.3 |
Patient Information Leaflets: Risk Factors for the Development of Breast Cancer
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