It is possible to categorize the risk factors that are effective in the development of breast cancer as follows:
Demographic Characteristics:Female gender is the most It is a major risk factor and represents a 100-fold increased risk. Increasing age is one of the most important risk factors as well as female gender. Today, a woman's lifetime risk of developing breast cancer is 1 in 8. Most of this risk occurs with advancing age.
One of the important paradoxes about breast cancer is that although the incidence is 20% higher in white women than in black women, the death rate is higher in black women. Ethnic differences are thought to be largely due to lifestyle and socioeconomic status.
Reproductive History: Increased exposure to estrogen hormone is associated with an increased risk of developing breast cancer. (early menarche [before age 12], late menopause [after age 55]); It is thought that reducing the duration of exposure to estrogen is protective. Terminal differentiation of the breast epithelium associated with full-term pregnancy is also protective, so having the first live birth at an older age and being nulliparous are associated with an increased risk of breast cancer. Nulliparity (never giving birth) causes a 1.2-1.7 fold increase in the relative risk of breast cancer. The protective effect of multiparity (having given birth many times) against breast cancer is controversial.
It is contradictory how infertility treatment affects the risk of breast cancer.
Induced or spontaneous miscarriage has not been shown to have a relationship with breast cancer.
Lactation reduces the risk of breast cancer. As expected, this effect is more evident especially in premenopausal women.
Familial/Genetic Risk Factors: It is known that 5-10% of breast cancer cases are familial. Family studies conducted on different cancers; It shows that the risk of cancer in the first and second degree relatives of the affected patient is increased compared to the normal population. Having a family history is an important risk factor for breast cancer. Having one first-degree relative with breast cancer increases the risk of breast cancer by 1.80 times. In the presence of two first-degree relatives, this risk increases 2.9 times. If a relative with breast cancer was diagnosed before the age of 30, the risk increases 2.9 times, and if the patient was diagnosed after the age of 60, the risk increases 1.5 times.
With the developments in the field of molecular genetics, different genes that cause the inheritance of cancer susceptibility have been identified. It is known that families/individuals carrying mutations in these genes have a high risk of cancer. This rapid development in cancer genetics affects the approach to the cancer patient and her family.
In breast cancer, which has a general population risk of 10-12%, gender, age, menarche and menopause age, nulliparity, atypical hyperplasia in breast biopsy, obesity, hormone replacement, In addition to the general risk factors known as oral contraceptive use, high-penetrance and low-penetrance genes, modifier genes and epigenetic factors are also known to be important.
Various genes associated with hereditary breast cancer have been identified. The most important of these genes are BRCA1/BRCA2 responsible for HBOC syndrome, TP53 responsible for LiFraumeni syndrome and PTEN genes responsible for Cowden syndrome.
Genetic approach in breast cancer cases; It consists of the stages of evaluation of the case, risk estimation, counseling before genetic test, genetic test and counseling after genetic test.
Environmental Factors:High socioeconomic level means a 2-fold increased risk for the development of breast cancer. It does. However, this condition is not considered an independent risk factor; Occurs due to change in reproductive habits Exposure to radiation increases the risk of breast cancer, especially between the ages of 10 and 14, when the breast is actively developing. Therapeutic radiotherapy applied to the thorax in the first 30 years of life also increases the risk of breast cancer. Exposure to radiation or radiotherapy after the age of forty-five does not affect the risk of breast cancer.
The relationship between radiation exposure resulting from diagnostic procedures and the risk of breast cancer is controversial. Except for those with a genetic transmission risk, this risk is considered non-existent or too low to be considered. The risk of developing breast cancer secondary to mammography is considered to be roughly one in a million.
Hormone Replacement Therapy (HRT) and Oral Contraceptive Use: Studies have shown that women taking HRT do not develop life-threatening breast cancer, regardless of the type and method of treatment given. has been shown to increase the risk. The risk of breast cancer resulting from HRT use is no different from risk factors such as alcohol use, excess weight (BMI >30 kg/m2), first birth after the age of 30, and late menopause.
Use of oral contraceptives in epidemiological studies. No relationship has been demonstrated between breast cancer risk. Although a large-scale study showed a relative risk increase of 1.24, this relationship could not be demonstrated in two recent studies.
Studies suggest that the amount and duration of alcohol consumption are also associated with an increase in the risk of breast cancer. Alcohol consumption is known to increase estradiol serum levels. Many studies have shown that moderate alcohol intake (1-2 drinks per day) causes a 30-50% increase in the incidence of breast cancer. A recent population-based study has shown that increased alcohol intake is effective in the development of estrogen receptor-positive breast cancer.
Increased physical activity (exercise) is associated with a reduced risk of breast cancer, especially in premenopausal women. Although this issue is very controversial, it is thought that regular exercise reduces the risk of breast cancer by increasing the number of anovulatory cycles.
Eating Habits: Eating foods with high fat content for a long time. There is some evidence to suggest that relin consumption may also contribute to an increased risk of breast cancer by increasing serum estrogen levels. However, the results of studies on the subject are contradictory.
Some studies have shown that there is an increase in the risk of breast cancer by eating red meat 5 times a week.
The relationship between increasing soybean oil consumption and reducing the risk of breast cancer is unclear. Therefore, there is no strong evidence to recommend a soy-rich diet to women living in Western societies to prevent breast cancer. However, it is not thought to be harmful.
Epidemiological studies in recent years have revealed that vitamin D may have a protective role against breast cancer.
Intake of antioxidants such as vitamin E, vitamin C or beta-carotene. There is no strong evidence that it affects breast cancer risk; Data regarding vitamin A are controversial. Although some studies have shown that low selenium levels increase the risk, the protective effect of high levels has not been demonstrated.
Studies have not shown a relationship between caffeine and breast cancer risk.
The relationship between smoking and breast cancer is also contradictory. . Although very different results have been obtained in studies, it is thought to increase the risk with some other accompanying factors.
Other Factors: Body Mass Index (BMI): Excessive Post-menopausal breast cancer is more common in overweight or obese women. If postmenopausal women who do not use HRT lose 10 kg or more after menopause, they have less risk than those who do not lose weight. In premenopausal overweight women, the risk is lower than in those who are not.
Proliferative Breast Lesions (without or containing atypia): Proliferative breast lesions, especially those containing cytological atypia, are risk factors for both non-invasive and invasive breast cancer. While there is a slight increase in a proliferative lesion that does not contain atypia (complex fibroadenoma, moderate or florid hyperplasia, sclerosing adenosis, intraductal papilloma); The risk is higher in proliferative lesions containing atypia (atypical lobular hyperplasia, atypical ductal hyperplasia). When atypia is multifocal, the risk increases 10 times. r.
Personal history of breast cancer: A personal history of invasive or in situ breast cancer increases the risk of developing invasive cancer in the contralateral (other) breast. The 10-year risk of contralateral invasive breast cancer for in situ lesions is 5%. In those with invasive breast cancer, the risk of developing contralateral breast cancer increases by 1% annually in premenopausal women and by 0.5% annually in postmenopausal women.
Dense breast structure: As an independent factor, it is associated with an increased risk of breast cancer. It is thought that the risk increases 4-5 times in women with mammographically dense breast structure.
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