Epidemiology and risk factors for breast cancer

DR.Mina tajvidi radiation oncologist

Epidemiology and risk factors for breast cancer

breast cancer is the most common female cancer, the second most common cause of cancer death in womenThe lifetime probability of developing breast cancer is one in six overall (one in eight for invasive disease)HRT may preferentially increase the risk of ER/PR-positive tumors twofold higher proportion of lobular cancers link HRT to lobular cancers— Breast cancer mortality rates have declined since 1975, attributed to the increased use of screening mammography and greater use of adjuvant therapiesDeclines have also been greater for women with ER/PR-positive as compared to ER/PR-negative tumors

RISK FACTORS Many risk factors have been associated with breast cancer: Age and gender Race and ethnicity Benign breast disease Personal history of breast cancer Lifestyle and dietary factors Reproductive and hormonal factors Family history and genetic factors Exposure to ionizing radiation Environment factors

RISK FACTORS AGE/GENDER :Breast cancer occurs 100 times more frequently in women than in men. Incidence rates rise sharply with age until about the age of 45 to 50 when the rise is less steep

RISK FACTORS 

RACE/ETHNICITY:Much of these ethnic differences are attributable to factors associated with lifestyle and socioeconomic statusBENIGN BREAST DISEASE: particularly those with cytologic atypia.PERSONAL HISTORY OF BREAST CANCER: A personal history of invasive or in situ breast cancer increases the risk of developing an invasive breast cancer in the contralateral breast. 1 and 0.5 percent per year

RISK FACTORS 

Socioeconomic status . Instead, the influence of socioeconomic status (educational, occupational, and economic level) is thought to reflect differing reproductive patterns with respect to parity, age at first birth, age at menarche, and utilization of screening mammographyGeographic residence are due to differences in known breast cancer risk factors such as reproductive hormonal factors including age at first birth or menarche and breastfeeding

RISK FACTORS 

Weight — Weight and body mass index (BMI) have opposite influences on postmenopausal as compared to premenopausal breast cancer. women with a BMI >33 kg/m2 had a 27 percent increased breast cancer risk compared to those with a BMI <21 kg/m2. mean serum estradiol levels were significantly higher among women with a BMI ≥ 29 kg/m2 compared to those with a BMI <21 kg/m2obesity is also associated with higher insulin levels, and hyperinsulinemia may also explain the obesity-breast cancer relationship [Obesity is also associated with a higher risk of dying from breast cancer. High BMI can be associated with irregular or long menstrual cycles or with polycystic ovary syndrome: women who were at least 175 cm (69 inches) tall were 20 percent more likely to develop breast cancer than those less than 160 cm (63 inches) tall

RISK FACTORS 

PhysCalcium/Vitamin D — Several studies suggest that intake of low-fat dairy products may protect against breast cancer, mainly in premenopausalical activity — Regular physical exercise appears to provide modest protection against breast cancerAn alternative diet hypothesis suggests that the influence of high fat diets may be more important during prepubertal years, particularly in influencing the early onset of menarcheAn association between intake of red meat (>5 servings per week) and ER/PR-positive premenopausal breast cancer was also observed in the Nurses' Health Study II Calcium/Vitamin D — Several studies suggest that intake of low-fat dairy products may protect against breast cancer, mainly in premenopausal

RISK FACTORS 

The high soy intake and low rates of breast cancer in Asian populations led to the hypothesis that soy consumption might decrease breast cancer risk by displacing estradiol and functioning as a relative antiestrogen.Antioxidants:Some studies on selenium suggest that the lowest levels may be associated with an increased riskSmoking — The relationship between cigarette smoking and breast cancer is controversial and complicated by the interaction of smoking with alcohol and the endogenous hormonal influences that alter breast cancer risk

RISK FACTORS 

Younger age at menarche is associated with a higher risk of breast cancer [108,109] . In one study, for every two-year delay in the onset of menarche, there was a 10 percent reduction in cancer riskLater menopause increases breast cancer risk [106,109,111] . The relative risk increases by 1.03 percent for each year Bilateral oophorectomy before the age of 40 reduces lifetime risk by 50 percent [112] ; yet, this risk reduction is eliminated if replacement estrogens are given.older at menopause, which is comparable to the increase with HRT useBilateral oophorectomy before the age of 40 reduces lifetime risk by 50 percent [112] ; yet, this risk reduction is eliminated if replacement estrogens are given

RISK FACTORS 

Parity — Nulliparous women are at increased risk for breast cancer compared with parous women; the relative risk ranges from 1.2 to 1.7Age at first birth — The younger a woman is at her first full-term pregnancy, the lower her breast cancer riskAbortion — Since abortion disrupts the maturation process of the breast, it has been hypothesized to increase breast cancer risBreastfeeding — A protective effect of breastfeeding has been shown in multiple case-control and cohort studies, the magnitude of which is dependent on the duration of breastfeeding, and on the confounding factor of parity

RISK FACTORS Endogenous hormone levels — Reproductive risk factors such as parity, age of menopause,Estrogen levels — Obese postmenopausal women have higher estrogen levels, due to the conversion of adrenal androgens to estrogens in fatty tissue; consequently, they have a higher risk of breast cancer tBone deEXPOSURE TO IONIZING RADIATION — Exposure to ionizing radiation of the chest at a young age, as occurs with treatment of Hodgkin lymphoma or in survivors of atomic bomb or nuclear plant accidents, is associated with an increased risk of breast cancer Because bone contains estrogen receptors and is highly sensitive to circulating estrogen levels, bone mineral density (BMD) may be a surrogate marker for long-term exposure to endogenous

RISK FACTORS 

Oral cCosmetic breast implants, electromagnetic fields, electric blankets, and hair dyes also have not increased risk in most studiesontraceptives — Many epidemiologic studies have failed to demonstrate an association between oral contraceptive use and the risk of breast cancer. However, a large pooled analysis calculated a small but significant increase in relative risk of breast cancer Infertility treatment — Whether ovulation induction for the treatment of infertility increases the risk of breast cancer is a matter of debateNocturnal light exposure — At least three studies and a meta-analysis support an association between exposure to light at night and the risk of breast cancerNSAID use — Aspirin and other nonsteroidal antiinflammatory drugs (NSAIDs) can inhibit the formation of both benign and malignant tumors

RISK FACTORS

RISK FACTORS FOR MALE BREAST CANCER — Men are more than one hundred times less likely to get breast cancer than women. Risk factors for male breast cancer include Klinefelter's syndrome, testicular and liver pathology, a family history of breast cancer, and BRCA2 mutations.

RISK FACTORS Lifestyle changes — A number of lifestyle changes may reduce breast cancer risk: Minimize duration of use of postmenopausal hormones. Consider non-estrogenic alternatives (eg, bisphosphonates for treatment of osteoporosis rather than hormones). Having a first child at an earlier age will decrease breast cancer risk. Breast feeding for at least six months may decrease breast cancer risk. Avoiding adult weight gain and maintaining a healthy weight will reduce postmenopausal breast cancer risk. Limiting alcohol consumption will reduce risk. For those who drink, adding folic acid to the diet may mitigate the increased risk [219] . (See "Overview of the risks and benefits of alcohol consumption", section on Breast cancer). Regular physical activity may also decrease risk

RISK FACTORS 

Medication — For women who are already at higher than average risk, their risk of developing breast cancer can be reduced by at least 50 percent or more by taking tamoxifen or raloxifene for five years.

RISK FACTORS 

Medication — For women who are already at higher than average risk, their risk of developing breast cancer can be reduced by at least 50 percent or more by taking tamoxifen or raloxifene for five years.Bisphosphonates — Oral bisphosphonates have been linked to esophageal adenocarcinoma and squamous cell carcinoma

tanks