risk factors of breast cancer

Risk Factors of Breast Cancer

Dr- Zainab A. Al-Dubisi

Contents Introduction. Epidemiology. Risk Factors. Recommendations. References.

Introduction

Breast cancer is the commonest female cancer.

The 2ndmost common cancer death in women.

The main cause of death in women ages 45- 55. 1/2cases can be explained by known risk factors.

15% are associated with +ve family history.

Cont…

Understanding the risk factors for breast cancer permits us to identify women at increased risk and intervene to modify risk, both individually and socially.

Epidemiology in KSA The recent data collected was in 2004 that by

Saudi Cancer Registry (SCR)

“Cancer Incidence Report in Saudi Arabia 2004”

It constitutes 11.5% of all cancers in Saudi. Breast cancer in female accounts for 22.4% of all

newly diagnosed cancer in female The ASR was 15.4/100,000 for female population.

The five regions with the highest ASR

Eastern region at 22.6/100,000. Riyadh region at 19.4/100,000. Makkah region at 19.1/100,000. Jouf region at 17.5/100,000 Qassim region at 12.6/100,000.

Epidemiology in U.S

The incidence of breast cancer increased during the 1980s but leveled off in the 1990s and declined between 2001 and 2003.

The current incidence is estimated at around 120/100,000 women.

Cont…

Annually: approximately 182,460 American

women are diagnosed with breast cancer.

40,480 die from the disease .

Cont…

The incidence of breast cancer is highest in developed countries:

North America & Western Europe.

Lowest incidences seen in:

South America, Africa and parts of Asia.

Survival rate The 5-year breast cancer survival rate 98%

for stage I cancer 16% for stage IV cancer 85% after 5 years 71% after 10 years 57% after 15 years 52% after 20 years www.emedicine.com

Risk Factors of Breast Cancer

Endogenous factors:

produced within or caused by the organism…

Exogenous factors:

Produced out side the body…

Endogenous factors

Age and gender. Family history and genetic factors . Race and ethnicity. Benign breast disease. Personal history of breast cancer. Hormonal & reproductive Factors. Bone & breast Density

Age & Gender

They are the strongest risk factors.

It is 100x > in female than male.

Annually, in U.S 182,460 women diagnosed with invasive breast cancers versus1900 in men.

Age

Breast cancer is rare in women< 25 y. Incidence increases with age, with a

plateau in women aged 50-55 y.

At age 75-80, the incidence decreases.

Family History

+ve family History is seen in 15-20 % of women with breast cancer.

The risk associated with having an affected 1st or 2nd degree maternal or paternal relative .

Cont… The lifetime risk is up to 4 times higher if

a mother or sister are affected.

The risk increased if: 1st degree relative affected by 1.80 fold. 2 affected 1st degree relatives, the risk

is increased 2.93 fold.

Cont…

The risk ratios were highest for women with young affected relatives.

Risk increased 2.9 fold for a woman whose relative was

diagnosed before age 30. 1.5 fold increased if the affected relative

was diagnosed after age 60. Medline ® Abstracts for References 188

of 'Epidemiology and risk factors for breast cancer

Genetics…

BRCA1, BRCA2,p53, ATM, and PTEN mutations are associated with higher risk.

Ataxia telangiectasia heterozygotes are at 4-times increased risk

Medline ® Abstracts for References.19, 189 of 'Epidemiology and risk factors for breast

cancer

Race and ethnicity

Compared with US women:

Individuals of Ashkenazi Jewish descent have a 2x greater risk.

Japanese and Taiwanese woman have

1/5 the risk.

Cont…

The highest rates occur in whites; that is

133 /100,000 The rate in blacks is 118/ 100,000 Asian Americans/Pacific Islanders is

89/100,000 American Indians/Alaska natives is

70/ 100,000 Medline ® Abstracts for

References of 'Epidemiology and risk factors for breast cancer

Cont...

Benign breast disease

Proliferative lesion:

1-without atypia (complex fibroadenoma, moderate or florid hyperplasia, sclerosing adenosis, intraductal papillomas) relative risk

1.3 to 2. (

2-with atypia (atypical lobular hyperplasia, atypical ductal hyperplasia) (relative risk 4 to 6)

Cont…

Nonproliferative lesions:

1-Single (fibrocystic change, solitary papilloma, simple fibroadenoma) are not associated with an increased risk for breast cancer.

2-Muliple may increase the risk for breast cancer modestly (1.8% at 10y-one cohort

study) . Medline ® Abstract for

Reference 25 of 'Epidemiology and risk factors for breast cancer'

PERSONAL HISTORY OF BREAST

CANCER 

In Pt with personal Hx of:

Invasive breast cancer the risk of developing invasive breast cancer in the contralateral breast is 1.5% yearly.

In situ lesions the 10-year risk of developing a contralateral invasive breast cancer is 5% Medline ®

Abstract for Reference 27 of 'Epidemiology and risk factors for breast cancer'

Other Pathology

Risk is increased with Hx of ovarian cancer, endometrial cancer,

Risk is decreased with cervical cancer.

Hormonal/Reproductive Factors

Factors increasing the number of menstrual cycles increase the risk, probably due to increased endogenous estrogen exposure..

(1) Menarche < 13 years. (1) Nulliparity (2) 1st pregnancy > 30 years. (4) No breastfeeding. (5) Menopause > 50 years.

Breastfeeding

Breast feeding…

protective effect 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.

Medline ® Abstracts for References 69 of 'Epidemiology and risk factors for breast cancer

Bone & Breast density  

Bone density: In multiple studies, women with higher bone density had a higher breast cancer risk.

Breast density: dense breast tissue is

independently associated with an increased risk of breast cancer.

Medline ® Abstracts for References of 'Epidemiology and risk factors for breast cancer

Exogenous factors

Exogenous hormones . Weight. Socioeconomic Status. Exposure to ionizing radiation. Environment factors .

Hormonal Therapy

Long-term use of HT is associated with the highest risk. In contrast, short-term HT appears not to increase the risk of breast cancer significantly

The use of combined estrogen plus progesterone is associated with an increased relative risk of breast cancer

Weight

Obesity: Increased risk is probably due to adipose conversion of androgens to estrogens.

Cont..

Women> 80 kg have 25 % higher risk compared to those weighing< 60 kg , after adjusting for height .

BMI >33 kg/m2 has a 27% increased breast cancer risk compared to those with a BMI <21 kg/m2.

Dose the height considerer factor for breast cancer?

Yes, it dose

Cont…

Increased height has been associated with a higher risk.

Women > 175 cm tall were 20% more likely to develop breast cancer than those < 160 cm.

Medline ® Abstracts for References 33,34,45 of 'Epidemiology and risk factors for breast cancer

Seven prospective cohort studies 2000-sep-15

Socioeconomic class

Women of higher socioeconomic status are at greater risk for breast cancer.

It is independent factors that may reflect differing reproductive patterns

Medline ® Abstract for Reference 28 of 'Epidemiology and risk factors for breast cancer '

  lifestylePhysical Activity Regular physical exercise appears

to provide modest protection against breast cancer particularly in premenopausal women

Medline ® Abstracts for References 46-48 'Epidemiology and risk of breast cancer

Cont…

Dietary

Red meat  An association between intake of (>5 servings per week) and premenopausal breast cancer .

Cont…

Fat intake has significant impact on breast cancer risk that was suggested in a meta-analysis of studies of both premenopausal and postmenopausal women

Cont…

Alcohol intake It is associated with an increased

risk of hormone receptor-positive breast.

Medline ® Abstracts for References 'Epidemiology and risk of breast cancer

Antioxidants

There is no strong evidence for an effect of intake of vitamin E, C or beta-carotene on breast cancer risk

The data are conflicting on vitamin A and breast cancer.

Medline ® Abstracts for References 203,204f 'Epidemiology and risk factors for breast cancer

Environmental Factors

Organochlorines include polychlorinated biphenyls (PCB's), dioxins, and organochlorine pesticides such as DDT are persisting in body tissues for years

Medline ® Abstracts for References 203,204f 'Epidemiology and risk factors for breast cancer

Ionizing radiation

Ionizing radiation on the chest at a young age.10-14 yrs

Risk is seen up to 45 years & no risk after that.

Medline ® Abstracts for References 203,204f 'Epidemiology and risk factors for breast cancer

RecommendationsPrimary cancer prevention

evidence

1-Maintain a healthy weight throughout life

A - Consistent (Level 1) evidence

that overweight and obesity are significant risk factors for cancers of the breast

Contd.

2-Adopt a physically active lifestyle

A - Consistent (Level 1) evidence indicates that physical activity offers significant protection for cancers of the breast

3-Consume a healthy diet, with an emphasis on plant source

B-Limited-quality evidence suggests that plant-based diets that have high amounts of fruits, vegetables and whole grains are protective for some cancers

4-Limit consumption of alcohol

A - Consistent (Level 1) evidence exists that high alcohol intake is associated with significantly and linearly increased risk of breast cancer.

References

www.emedicine.comww.medline.comwww.cochrane.comwww.pubmed.comwww.uptodate.comwww.AAFP.com.

Swanson’s Family Medicine Textbook.