Personal factors

Personal factors are general and physical factors about a woman that can influence her risk for breast cancer. These factors can include her age, place of residence, socioeconomic status, height, weight at birth and breast density. 

Age
Convincing

Convincing

There is compelling and consistent evidence that the factor increases or decreases the risk of breast cancer.

Getting older is associated with an increased risk of breast cancer.

Increasing age is one of the strongest risk factor for breast cancer, other than being female. Based on incidence rates in Australia, women who are 50 years old are approximately 10 times more likely to develop breast cancer compared to women who are 30 years old.





In Australia, the average age of women diagnosed with breast cancer is 61 years. More than 75% of breast cancers in Australia are diagnosed in women aged 50 years or older. Approximately 0.5% of all breast cancers in Australia are diagnosed in women under 30 years, 4% in women aged 30-39 years, and 16% diagnosed in women aged 40-49 years.1

The longer a woman lives, the more mutations occur in the body’s cells, and the more likely it is that these mutated cells will progress to cancer.

Evidence classification: Convincing

There is convincing evidence that increasing age is associated with an increased risk of breast cancer.

Age is the most significant factor for developing breast cancer (other than being female).

Mechanisms

Changes or aberrations in the genome, such as DNA mutations, can contribute to the development of cancer. There are different genetic changes or ‘drivers’ of cancer, such as changes in oncogenes (cancer-causing genes), tumour suppressor genes (genes that usually protect cells from abnormal proliferation), or DNA repair genes. These changes can be inherited or can arise during a person’s lifetime due to errors as cells divide or damage to DNA caused by certain environmental exposures.2

The longer a person lives, the more mutations occur in cells and the more likely it is that cells may progress to cancer.

Evidence

In Australia, the risk of breast cancer increases rapidly from the age of 30–34 years (25.6 per 100 000 in 2014) to 50–54 years (255.9 per 100 000 in 2014).1 It increases more slowly to a peak around 70–74 years of age (412.4 per 100 000 in 2014), and then decreases (317.6 per 100 000 for women aged 85+ years in 2014).1 This equates to a risk of diagnosis of 1 in 10 before the age of 75 and 1 in 8 before the age of 85. Based on incidence rates in Australia1, women aged 50 years are at approximately 10 times higher risk of breast cancer compared to women aged 30 years.

The average age of women diagnosed with breast cancer in Australia is 61 years.1 Approximately 0.5% of all breast cancers in Australia are diagnosed in women under 30 years, 4% in women aged 30-39 years, and 16% diagnosed in women aged 40-49 years.1 Approximately 79% of all breast cancers in Australia are diagnosed in women aged 50 years or more.1

Data from the United States indicate that, if women less than 65 years of age are compared with women aged 65 years or older, the relative risk of breast cancer associated with age is 5.8.3





Read the full Review of the Evidence

References
  1. Australian Institute of Health and Welfare (2017). Australian cancer incidence and mortality (ACIM) books, AIHW, Canberra, https://www.aihw.gov.au/reports/cancer/acim-books/contents/acim-books.
  2. PDQ Screening and Prevention Editorial Board. Breast Cancer Prevention. Bethesda MD: National Cancer Institute. Updated 2018. [Available from: https://www.cancer.gov/types/breast/hp/breast-prevention-pdq.]
  3. Singletary SE (2003). Rating the risk factors for breast cancer. Annals of Surgery 237(4):474–482.
Place of residence
Convincing

Convincing

There is compelling and consistent evidence that the factor increases or decreases the risk of breast cancer.

Living in certain countries is associated with an increased risk of breast cancer.

Different countries have different rates of breast cancer. Australia has lower rates than some European countries, but higher rates than Asian and South American countries.

Differences in breast cancer risk between countries may be due to a range of factors. Lifestyle factors that are associated with breast cancer risk, such as body weight and physical activity, might vary between different countries.

Reproductive factors might also differ between countries. For example, in some countries, women might tend to have their first child at a later age, have fewer children or breastfeed for less time in total. These factors are all related to the risk of breast cancer.

Even within countries, breast cancer risk may vary between different ethnic groups due to a range of factors such as reproductive, lifestyle and genetic factors. For example, in Australia, breast cancer incidence differs between Indigenous and non-Indigenous women.

Evidence classification: Convincing

There is convincing evidence that living in certain countries is associated with increased risk of breast cancer.

The incidence of breast cancer differs substantially in different countries. Australia has lower rates than some European countries, but higher rates than Asian and South American countries.

Mechanisms

Differences in breast cancer incidence between countries may reflect different lifestyle and reproductive factors.

Lifestyle differences might include differences in diet and obesity, which are associated with risk of breast cancer.

Differences in reproductive patterns might include differences in a woman’s likely age at birth of the first child, in the number of children a woman is likely to have and duration of breastfeeding – all of these are associated with breast cancer risk.4

Evidence 

The highest breast cancer rates are reported from countries in northern and western Europe (eg 105.9 per 100,000 in the Netherlands), Australia (94.5 per 100,000), New Zealand (92.6 per 100,000) and North America (84.9 per 100,000 in the United States).1,2 The lowest rates are reported from countries in Africa (eg 27.9 per 100 000 in middle Africa), eastern Asia (eg 57.6 per 100,000 in Japan) and South America (eg 40.9 per 100,000 in Chile).1

Breast cancer incidence rates are increasing in developing countries.2

There are also differences between countries in the median age at diagnosis of breast cancer. The age at diagnosis is higher in developed countries than in Asia and Africa.2

Even within countries, breast cancer risk may vary between different ethnic groups due to a range of factors such as reproductive, lifestyle and genetic factors. For example, in Australia, breast cancer incidence differs between Indigenous and non-Indigenous women.3 The age-standardised breast cancer incidence rate is lower for Aboriginal and Torres Strait Islander women at 98.8 per 100,000 (2009–2013) compared with 111.7 per 100,000 in 2009–2013 for non-Indigenous women.1 Internationally, there are lower breast cancer incidence rates for Indigenous compared with non-Indigenous populations, except for Indigenous women in Alaska and New Zealand who have higher rates than their non-Indigenous counterparts.3,5

Differences in breast cancer incidence associated with a woman’s country of birth have been reported in a New South Wales (NSW) study.4 The highest rates of breast cancer in NSW were in women born in the Western world, typically English speaking areas.4 The breast cancer incidence rates averaged for 2004–2008 were: women born in Australia (81.9 per 100,000), New Zealand (91.4 per 100,000) and Western Europe (84.4 per 100,000), compared with women born in southeast Asia (62.7 per 100,000), East Asia (57.2 per 100,000), and high-income Asia Pacific countries (49.8 per 100,000).4 Over time, migrants tend to experience the breast cancer incidence rates of their adoptive countries. For example, changes in lifestyle, including adoption of a western diet, less physical activity and more overweight and obesity associated with acculturation among Asian women is suggested to have contributed to the increased incidence of breast cancer observed in this population group in the United States.6,7

Read the full Review of the Evidence

References
  1. Cancer Australia (2018). National cancer control indicators: cancer incidence, https://ncci.canceraustralia.gov.au/diagnosis/cancer-incidence/cancer-incidence
  2. Ginsburg O, Bray F, Coleman MP, et al. (2017). The global burden of women’s cancers: a grand challenge in global health. Lancet 389(10071):847–860.
  3. Moore SP, Antoni S, Colquhoun A, et al. (2015). Cancer incidence in indigenous people in Australia, New Zealand, Canada, and the USA: a comparative population-based study. Lancet Oncology16(15):1483–92.
  4. Feletto E, Sitas F (2015). Quantifying disparities in cancer incidence and mortality of Australian residents of New South Wales (NSW) by place of birth: an ecological study. BMC Public Health15:823.
  5. Teng AM, Atkinson J, Disney G, et al. (2016). Ethnic inequalities in cancer incidence and mortality: census-linked cohort studies with 87 million years of person-time follow-up. BMC Cancer 16(1):755.
  6. Institute of Medicine (IOM). Breast cancer and the environment: A life course approach. Washington, DC: The National Academies Press; 2012 [Available from: http://www.nationalacademies.org/hmd/Reports/2011/Breast-Cancer-and-the-Environment-A-Life-Course-Approach.aspx.]
  7. Liu L, Zhang J, Wu AH, et al. (2012) Invasive breast cancer incidence trends by detailed race/ethnicity and age. International Journal of Cancer130(2):395–404.
Remoteness of residence
Convincing

Convincing

There is compelling and consistent evidence that the factor increases or decreases the risk of breast cancer.

Living in urban areas compared with living in rural and remote areas is associated with increased risk of breast cancer. This is the case in both Australia and other developed countries.

These differences may be because of a range of lifestyle and reproductive factors which affect risk of breast cancer. Differences in reproductive patterns might include a woman’s age at the birth of her first child and the number of children she has. In addition, women living in urban areas might be more likely to access screening and diagnostic services for early detection of breast cancer.

Evidence classification: Convincing

There is convincing evidence that living in an urban area rather than a more remote area is associated with increased risk of breast cancer.

Mechanisms

Remoteness or urbanisation is related to socioeconomic status. Living in an area of higher socioeconomic status is associated with increased risk of breast cancer.

Differences in breast cancer incidence between urban and remote areas may reflect different lifestyle factors, such as levels of physical activity.

In addition, women living in urban areas might have better access to screening and diagnostic services for early detection of breast cancer.1

Evidence 

In Australia in 2009–13, the age-standardised breast cancer incidence was 121.1 per 100,000 for women living in major cities and 106.4 per 100,000 for women living in very remote areas.2

A systematic review and meta-analysis of studies conducted in the United States, Canada, the United Kingdom, Australia, Italy and Switzerland indicated that living in urban versus rural areas was associated with a 9% higher breast cancer incidence (pooled relative rate for urban vs rural 1.09; 95% confidence interval 1.01–1.19).3

Read the full Review of the Evidence

References
  1. Dasgupta P, Baade PD, Youlden DR, et al. (2018). Variations in outcomes by residential location for women with breast cancer: a systematic review BMJ Open 8:e019050.
  2. Cancer Australia (2018). National cancer control indicators: cancer incidence, https://ncci.canceraustralia.gov.au/diagnosis/cancer-incidence/cancer-incidence.
  3. Akinyemiju TF, Genkinger JM, Farhat M, et al. (2015). Residential environment and breast cancer incidence and mortality: a systematic review and meta-analysis. BMC Cancer 15:191.
Socioeconomic status
Convincing

Convincing

There is compelling and consistent evidence that the factor increases or decreases the risk of breast cancer.

Living in an area of greater affluence is associated with increased risk of breast cancer.

In both Australia and other developed countries, women who live in areas of higher socioeconomic status have a higher incidence of breast cancer than women who live in more disadvantaged areas.

There might be a number of factors that explain this difference including reproductive factors, lifestyle factors and remoteness of residence. In addition, women living in more affluent areas might be more likely to access screening and diagnostic services for early detection of breast cancer.

Evidence classification: Convincing

There is convincing evidence that living in an area of higher socioeconomic status is associated with increased risk of breast cancer.

This relationship has been found in Australia and other developed countries.

Mechanisms

Differences in breast cancer incidence between areas of different socioeconomic status may reflect different reproductive and lifestyle factors.

Differences in reproductive patterns might include differences in a woman’s likely age at birth of the first child and in the number of children a woman is likely to have – both of these are associated with breast cancer risk.

In addition, women living in more advantaged areas might be more likely to access screening and diagnostic services for early detection of breast cancer.

In Australia, socioeconomic status is also related to Indigenous status and remoteness of residence, which are both associated with breast cancer risk.

Evidence 

In Australia in 2009-13, age-standardised breast cancer incidence was 110.9 per 100 000 for women in the most socioeconomically disadvantaged quintile, compared with 133.0 per 100 000 in the least disadvantaged quintile.1

A systematic review and meta-analysis of studies conducted in the United States, Canada, the United Kingdom, Australia, Italy and Switzerland indicated that living in socioeconomic areas characterised by higher income was associated with higher breast cancer incidence.2

In the United States, an analysis of breast cancers diagnosed in 2010 noted that the higher breast cancer incidence for women living in areas of high socioeconomic status was observed across all ethnic groups.3

Read the full Review of the Evidence

References
  1. Cancer Australia (2018). National cancer control indicators: cancer incidence, https://ncci.canceraustralia.gov.au/diagnosis/cancer-incidence/cancer-incidence.
  2. Akinyemiju TF, Genkinger JM, Farhat M, et al. (2015). Residential environment and breast cancer incidence and mortality: a systematic review and meta-analysis. BMC Cancer 15:191.
  3. Akinyemiju TF, Pisu M, Waterbor JW et al. (2015). Socioeconomic status and incidence of breast cancer by hormone receptor subtype. Springerplus 4:508.
Birthweight
Probable

Probable

The factor is likely to be associated with increased or decreased risk of breast cancer, but the evidence is not as strong as for convincing.

 

Premenopausal women

Having a higher birthweight is probably associated with an increased risk of breast cancer in premenopausal women.

The risk of premenopausal breast cancer increases by about 5% for each 500 g increase in birthweight.

It is likely that this is due to other factors that lead to higher birthweight, such as genetic and hormonal factors which both affect birthweight. Some of these factors could also affect breast cancer risk.

Postmenopausal women

There is no conclusive evidence that having a higher birthweight is associated with increased risk of postmenopausal breast cancer. The studies that have looked for a link between birthweight and risk of breast cancer in postmenopausal women have been inconsistent in their findings.

Evidence classifications: Probable (premenopausal breast cancer)


Evidence classifications: Inconclusive (postmenopausal breast cancer)

Higher birthweight is probably associated with an increased risk of breast cancer in premenopausal women. The increase in risk is estimated as 5% for each 500 g increase in birthweight (RR 1.05, 95% CI 1.02–1.09).1

The evidence for any association between birthweight and risk of postmenopausal breast cancer is inconclusive. Findings across cohort studies are inconsistent.

Mechanisms

Any association between birthweight and risk of breast cancer is unlikely to be causal. Rather, it is likely that factors that lead to higher birthweight are associated with an increased risk of breast cancer. Birthweight, which reflects prenatal growth, is determined by both genetic and environmental influences, which may include hormonal factors and foetal nutrition. Birthweight also predicts later growth and maturation (e.g. age at menarche), which affect breast cancer risk.1

Evidence 

The World Cancer Research Fund International/American Institute for Cancer Research (WCRF/AICR) has judged the evidence as ‘strong–probable’ for an association between higher birthweight and increased risk of premenopausal breast cancer.1 A dose-response analysis of 16 studies estimated the relative risk per 500g increase in birthweight as 1.05 (95% confidence interval 1.02–1.09). Some of the studies contributing to the dose-response analysis had not adjusted for age, alcohol intake, reproductive factors and/or adult body mass index.

For postmenopausal breast cancer risk, the WCRF/AICR considered that the evidence for an association with birthweight was limited, and no conclusion was possible.1

Findings from two recent large prospective cohort studies are consistent with the findings of the WCRF/AICR – that is, an increased risk of premenopausal but not postmenopausal breast cancer with higher birthweight.2,3 However, another cohort study found no association between birthweight and either premenopausal or postmenopausal breast cancer.4

Read the full Review of the Evidence

References
  1. World Cancer Research Fund/American Institute for Cancer Research (2018). Continuous Update Project Expert Report 2018. Diet, nutrition, physical activity and breast cancer. London, UK.
  2. Dartois L, Fagherazzi G, Baglietto L, et al. (2016). Proportion of premenopausal and postmenopausal breast cancers attributable to known risk factors: estimates from the E3N‐EPIC cohort. International Journal of Cancer 138(10):2415–2427.
  3. Xue F, Rosner B, Eliassen H et al. (2016). Body fatness throughout the life course and the incidence of premenopausal breast cancer. International Journal of Epidemiology 45(4):1103–1112.
  4. Sandvei MS, Lagiou P, Romundstad PR, et al. (2015). Size at birth and risk of breast cancer: update from a prospective population-based study. European Journal of Epidemiology 30(6):485–492.
Height
Convincing

Convincing

There is compelling and consistent evidence that the factor increases or decreases the risk of breast cancer.

Being taller as an adult is associated with an increased risk of breast cancer.

The risk of breast cancer increases by about 17% for each extra 10 cm in a woman’s adult height.

It is unlikely that height as an adult directly affects breast cancer risk. Rather, being taller and having an increased risk of breast cancer probably have mechanisms in common. For example, growth processes might affect both adult height and breast cancer risk. These are affected by both genetics and the environment, including nutrition.

Evidence classification: Convincing

There is convincing evidence that being taller as an adult is associated with an increased risk of breast cancer compared to being shorter.

The increased risk of breast cancer per 10 cm increase in height has been estimated as 17% (RR 1.17, 95% CI 1.15–1.19).1 It has been estimated as 6% for premenopausal breast cancer 1.06 (95% CI 1.02–1.11) and 9% (RR 1.09, 95% CI 1.07–1.11) for postmenopausal breast cancer.2

Mechanisms

It is unlikely that height as an adult directly affects breast cancer risk. Rather, shared mechanisms – for example, growth processes – may determine both height and cancer risk. Growth processes are affected by genetic and environmental, e.g. nutritional, factors.3

Evidence 

The World Cancer Research Fund International/American Institute for Cancer Research concluded that the ‘developmental factors leading to greater linear growth (marked by adult attained height)’ are a convincing cause of premenopausal and postmenopausal breast cancer.2 This was based on evidence from 29 studies reporting on premenopausal breast cancer and 41 studies reporting on postmenopausal breast cancer. The increased risk of breast cancer per 5 cm increase in adult height was 1.06 (95% confidence interval [CI] 1.02–1.11) for premenopausal breast cancer and 1.09 (95% CI 1.07–1.11) for postmenopausal breast cancer.

A meta-analysis of a large number of prospective studies estimated that the increased risk of breast cancer per 10 cm increase in adult height was 1.17 (95% CI 1.15–1.19).1 The estimate was similar for premenopausal and postmenopausal breast cancer. The increase was not seen for oestrogen receptor-negative (ER-) disease.

A significant association between greater height and risk of premenopausal and postmenopausal ER+ breast cancer was found in another large cohort study.4 However, a cohort study of Japanese women did not find an association between adult height and breast cancer risk.5

Read the full Review of the Evidence

References
  1. Zhang B, Shu XO, Delahanty RJ, et al. (2015). Height and breast cancer risk: evidence from prospective studies and Mendelian randomization. Journal of the National Cancer Institute 107(11).
  2. World Cancer Research Fund/American Institute for Cancer Research (2018). Continuous Update Project Expert Report 2018. Diet, nutrition, physical activity and breast cancer. London, UK.
  3. Elands RJ, Simons CC, Riemenschneider M, et al. (2017). A systematic SNP selection approach to identify mechanisms underlying disease aetiology: linking height to post-menopausal breast and colorectal cancer risk. Scientific Reports 24(7):410.
  4. Horn-Ross PL, Canchola AJ, Bernstein L, et al. (2016). Lifetime body size and estrogen-receptor-positive breast cancer risk in the California Teachers Study cohort. Breast Cancer Research 18(1):132.
  5. Nitta J, Nojima M, Ohnishi H, et al. (2016). Weight gain and alcohol drinking associations with breast cancer risk in Japanese postmenopausal women: results from the Japan Collaborative Cohort (JACC) Study. Asian Pacific Journal of Cancer Prevention 17(3):1437–1443.
Breast density
Convincing

Convincing

There is compelling and consistent evidence that the factor increases or decreases the risk of breast cancer.

Higher than average mammographic breast density is associated with an increased risk of breast cancer.

Breast density is something that can only be seen on a mammogram. Breast density is not related to how breasts look or feel and is not based on size or firmness. Breast density reflects the relative amounts of dense glandular breast tissue, which appears white on a mammogram, compared with non-dense fatty tissue, which appears dark on a mammogram.

The mechanism linking breast density with breast cancer risk is not well understood. Breast density is associated with genetic and several other established risk factors for breast cancer, including body mass index (BMI) and whether a woman has had children.

Evidence classification: Convincing

There is convincing evidence that higher than average mammographic breast density is associated with an increased risk of breast cancer. Conversely, lower than average mammographic breast density is associated with a decreased risk of breast cancer.

The increased risk of breast cancer associated with higher percent breast density has been estimated as 1.53 per standard deviation from the mean (95% CI 1.44–1.64).1 Approximately 70% of women will have an increased or decreased risk of breast cancer, associated with breast density, between 1.53 (moderately dense breasts) and 0.65 (moderately non-dense breasts).

Women with extremely dense breasts (BI-RADS 4) and women with heterogeneously dense breasts (BI-RADS 3) have approximately 2.14 times and 1.28 times increased risk of breast cancer compared to women with average breast density, respectively. Conversely, women with scattered fibroglandular densities (BI-RADS 2) and almost entirely fatty breasts (BI-RADS 1) have approximately 0.80 times and 0.48 times decreased risk of breast cancer compared to average breast density, respectively.

Mechanisms

Breast density refers to the appearance of the breast on a mammogram. It reflects the relative amounts of stromal and epithelial tissues (‘glandular tissue’, white in appearance) and fat (dark in appearance) in the breast.2 Glandular tissue is denser.

The main tool used to classify mammographic breast density is the Breast Imaging Reporting and Data System (BI-RADS) which uses four categories:

  • BI-RADS 1: Almost entirely fat—less than 25% glandular tissue
  • BI-RADS 2: Scattered fibroglandular densities—approximately 25–50% glandular tissue
  • BI-RADS 3: Heterogeneously dense—approximately 51–75% glandular tissue
  • BI-RADS 4: Extremely dense—greater than 75% glandular tissue.

International research3-7 suggests that the distribution of breast density into BI-RADS categories 1–4 is approximately 10%, 40%, 40%, and 10% of women, respectively.

The mechanism linking breast density with breast cancer risk is not well understood. A higher breast density means a higher proportion of glandular tissue in the breast and a greater number of stromal and epithelial cells that are at risk of becoming cancer cells.8

A range of other factors contribute to breast density including genetics, age, body mass index (BMI) and hormones.9 Breasts tend to become less dense as women get older, especially after menopause, as the glandular tissue degenerates and the breasts become more fatty. Breast density is also lower in women who have had children than in women who have not,10 decreases with increasing BMI11,12 and is higher in women who use combined menopausal hormone therapy (MHT).13 In addition, since cancers appear as white areas on a mammogram, there is potential for breast cancer to be missed as a result of the masking effect associated with breast density.14

Evidence 

A collaborative analysis of 13 case-control studies examining the association between mammographic density and breast cancer risk showed an increased risk of premenopausal and postmenopausal breast cancer with higher breast density.1 The odds ratio per standard deviation (SD) was 1.53 (95% confidence interval [CI] 1.44–1.64) for per cent dense area (PDA) for postmenopausal breast cancer, with very similar odds for premenopausal breast cancer. These estimates were adjusted for age, BMI, and whether the woman had had children.

The odds ratio per SD of 1.53 relates to the 85th percentile of density, and conversely an odds ratio of 0.65 (the inverse of 1.53) relates to the 15th percentile of density. This can be interpreted as women with moderately dense breasts on mammography having 1.53 times increased risk of breast cancer and women with moderately non-dense breasts having 0.65 times decreased risk of breast cancer, compared to women with average breast density. Approximately 70% of women will have a risk of breast cancer associated with breast density in between these two values.

An odds ratio per SD of 1.53 for PDA can also be interpreted as a relative risk for each BI-RADS category. Assuming a distribution of women in BI-RADS categories 1-4 of 10%:40%:40%:10%5, respectively, women with extremely dense breasts (BI-RADS 4) have around 2.14 times increased risk of breast cancer than women with average breast density and women with heterogeneously dense breasts (BI-RADS 3) have around 1.28 times increased risk of breast cancer than women with average breast density. Conversely women with scattered fibroglandular densities (BI-RADS 2) have around 0.80 times decreased risk of breast cancer than women with average breast density; and women with the least dense breasts (BI-RADS 1) have around 0.48 times decreased risk of breast cancer than women with average breast density.1

An increased risk of breast cancer in women with higher breast density compared with women with the least dense breasts has also been found in two additional meta-analyses12,13, prospective data from a randomised controlled trial of mammographic screening15 and a recent retrospective study.7

Read the full Review of the Evidence

References
  1. Pettersson A, Graff RE, Ursin G, et al. (2014). Mammographic density phenotypes and risk of breast cancer: a meta-analysis. Journal of the National Cancer Institute 106(5): dju078.
  2. Yaghjyan L, Mahoney MC, Succop P, et al. (2012). Relationship between breast cancer risk factors and mammographic breast density in the Fernald Community Cohort. British Journal of Cancer 106(5):996–1003.
  3. BreastScreen Australia (2016). Breast Density and Screening: Position Statement http://www.cancerscreening.gov.au/internet/screening/publishing.nsf/Content/br-policy-breast-density
  4. Kerlikowske K, Ichikawa L, Miglioretti DL, et al. (2007). Longitudinal measurement of clinical mammographic breast density to improve estimation of breast cancer risk. Journal of the National Cancer Institute 99:386‒395.
  5. Sprague BL, Gangnon RE, Burt V, et al. (2014) Prevalence of mammographically dense breasts in the United States. Journal of the National Cancer Institute 106(10): dju.255
  6. Sickles E, D’Orsi C, Bassett L, et al. (2013). ACR BI-RADS Atlas: Breast imaging reporting and data system. Reston, VA: American College of Radiology 123–6
  7. Moshina N, Sebuødegård S, Lee CI, et al. (2018). Automated volumetric analysis of mammographic density in a screening setting: worse outcomes for women with dense breasts. Radiology 288 (2):343–352.
  8. Boyd NF, Dite GS, Stone J, et al. (2002). Heritability of mammographic density, a risk factor for breast cancer. New England Journal of Medicine 347:886–894.
  9. Baglietto L, Krishnan K, Stone J, et al. (2013). Associations of mammographic dense and nondense areas and body mass index with risk of breast cancer. American Journal of Epidemiology. 179(4):475‒483.
  10. Wang AT, Vachon CM, Brandt KR, et al. (2014). Breast density and breast cancer risk: a practical review. Mayo Clinic Proceedings 89(4):548–557.
  11. Zhu W, Huang P, Macura KJ et al. (2016). Association between breast cancer, breast density, and body adiposity evaluated by MRI. European Radiology 26(7):2308–2316.
  12. Boyd NF, Martin LJ, Sun L, et al. (2006). Body size, mammographic density, and breast cancer risk. Cancer Epidemiology, Biomarkers & Prevention 15(11):2086–2092.
  13. McTiernan A, Martin CF, Peck JD, et al. (2005). Estrogen-plus-progestin use and mammographic density in postmenopausal women: Women’s Health Initiative randomized trial. Journal of the National Cancer Institute 97(18):1366–1376.
  14. Boyd NF, Guo H, Martin LJ, et al. (2007). Mammographic density and the risk and detection of breast cancer. New England Journal of Medicine 356 (3):227–236
  15. Chiu Y, Duffy S, Yen AM, et al. (2010). Effect of baseline breast density on breast cancer incidence, stage, mortality, and screening parameters: 25-year follow-up of a Swedish mammographic screening. Cancer Epidemiology, Biomarkers & Prevention 19(5):1219–1228.



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