Risk Factors
Breast Cancer
Breast Cancer risk factor | genetic | malignant | stats | staging | metastic | unusual cancer

 

Risk factors for breast cancer

 

Obviously age and sex are most important risk factos for breast cancer.Cancer of the breast is less common in women under thirty years old although it is occurring more frequently in younger and younger women. Also breast cancer is rare in males; female cancer of the breast is one hundred times more prevalent than male breast cancer. Another important factor in the epidemiology of breast cancer is the country of origin; thus while it is a very common disease in the west, e.g. in UK and the USA, it is far less common in Japan. South Africa falls somewhere in between these two poles, although breast cancer is still the most common cancer effecting women in South Africa. Dietary factors may play a role here. Thus Japanese migrants to the USA assume the higher western rate of breast cancer within two generations, possibly because they adopt an American lifestyle.

 

Other risk factors are:

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Family history of breast cancer on both mother and father’s side. If a mother or sister has or had breast cancer at a young age (30-40) then the woman’s risk is doubled (see below).

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Family history of any cancer is also relevant as cancers such as uterine, skin, prostate, stomach, colon and breast occur together in clusters.

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First pregnancy after thirty years of age.

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Oestrogen exposure. Abnormally prolonged exposure to oestrogen increases risks. Early menarche (menstruation begins at ages around 10 or 11 years) and late menopause (menstruation ceases at age around fifty-five years). This exposes the women to prolonged oestrogen risk and at least doubles the incidence of breast cancer. Oestrogen appears to be a “promoter” of breast cancer.

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Lifestyle (saturated fat and alcohol). There is a correlation between the intake of saturated fats and the incidence of breast cancer.

 

Obesity is associated with a twofold increase in risk of breast cancer in postmenopausal women. Increased body fat appears to be associated with raised oestrogen levels.

Alcohol is a risk factor for breast cancer, particularly in the younger woman. It is well known that alcohol is a liver poison and as the liver is the site of oestrogen metabolism, alcohol may result in raised oestrogen levels, as the damaged liver does not metabolize oestrogen appropriately. More than two tots of alcohol per night increases ones risk by 24%.

 

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Oral contraceptive pill. Overall, there appears to be little risk of increasing the incidence of breast cancer. Thus the pill is generally safe. However, taking oral contraceptives for over ten years by young females before their first pregnancy (oestrogen window period) appears to increase the risk of pre-menopausal breast cancer slightly.

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Hormone replacement therapy (HRT or oestrogen administration). Studies have demonstrated that the risk of breast cancer does indeed increase after using HRT for more than five years. Nevertheless, the benefits of HRT for osteoporosis (thin bones that break easily), possibly Alzheimer’s disease and finally menopausal symptoms (such as hot flushes, emotional lability, dry vagina and so on), suggest that women who start menopause at a young age and are severely symptomatic should go onto HRT. The disadvantages are increased risk of cancer of the breast and uterus (womb).

 

In general, most doctors recommend using HRT in women who are suffering from significant menopausal symptoms, but patients must be carefully monitored for breast cancer while on treatment and should go for yearly mammograms and ultrasound. By adding a progestogen to the oestrogen, the uterine cancer incidence after HRT is decreased, but not eliminated. Use of HRT for longer than five years is not recommended.

The development of the SERM (selective oestrogen receptor modulator) group of drugs. SERM’s mimic the action of oestrogen in the body to prevent bone loss and guard against heart disease, without increasing the risk of breast cancer that is now associated with long-term hormone replacement therapy (HRT). SERMs vary in the length and shape of a critical side chain, which influences their interaction with the oestrogen receptor. Raloxifene, for example, binds less efficiently than tamoxifen in experimental models. Fulvestrant interacts quite differently with the oestrogen receptor, leading to its destruction rather than to its inactivation. Raloxifene and fulvestrant should not be proposed as a substitute for tamoxifen unless this is done within the context of a controlled clinical trial.

 

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Age of first pregnancy – protective if less then twenty years old. Nulliparity (no pregnancy) and late age of a first pregnancy increase risk (oestrogen window period prolonged).

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A period of breastfeeding is protective against breast cancer.

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Exercise is protective. Cardiovascular exercise more than three times a week decreases the risk of cancer by 38%.

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Certain vegetables containing the indol 3 carbinols are protective against breast cancer (these are found in the cruciferous vegetables such as broccoli).

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It should be noted that over 60% of all women presenting with breast cancer do not have any risks for breast cancer development.

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A typical epithelial hyperplasia – this is a diagnosis made on a biopsy.Lobular carcinoma in situ also increases the risk for breast cancer. This is a proliferative disorder of the breast during the involution stage of ANDI. This increases the risk of breast cancer by a factor of five.

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Irradiation. Teenagers exposed to radiation during the second world war (Hiroshima and Nagasaki where the atom bombs exploded) had double the incidence of cancer of the breast (certain other cancers were also seen to increase in these women).