Breast Cancer

1
Breast Cancer

• Is there a link to
• Endocrine Disrupting Chemicals?
• Suzanne M. Snedeker, Ph.D.
• Assoc. Director for Translational Research
• Cornell Universitys
• Program on Breast Cancer and Environmental
  Risk Factors (BCERF)
• sms31_at_cornell.edu
• http//www.cfe.cornell.edu/bcerf/

2
Presented at the

• 2nd Copenhagen Workshop on
• Endocrine Disrupters
• A Possible Role of Mixed Exposures for
  Reproductive Failures and Malignancies
• Session 1 EDC Effects in Humans
• December 7th, 2002
• Rigshospitalet (Copenhagen University Hospital)
• Copenhagen, Denmark

3
Contribution of established factors to breast
cancer risk

• National surveys of US white women
• 40-50 of breast cancer risk
• Age first birth / nulliparity
• Family history of breast cancer
• Higher income
• Ref Madigan et al., J National Cancer Institute,
  871681-5, 1987
• North Carolina Breast Cancer Study
• 25 of breast cancer risk
• Menarche before 14 yrs
• First birth at or after 20 yrs / nulliparity
• Family history of breast cancer
• History of benign breast disease
• Ref Rockhill et al., American J Epidemiology,
  147826-33, 1998

4
Environmental links to breast cancer

• Scandinavian Twin Study
• 27 of risk, Heritable factors
• 73 of risk, Environmental factors
• 6 of risk, shared environment
• 67 of risk, non-shared environment
• Suggests that environmental factors play a major
  role in the causation of breast cancer
• Ref Lichtenstein et al., New England J of
  Medicine, 34378-85, 2000

5
Risks Related to Breast Cancer
Close Relative
Genetics
Advancing Age
Gender
Age at First Birth
Passive Smoke
Early Menarche
Late Menopause
Breast Feeding
Education Income
Overweight (post-menopause)
Chemicals -Work -Home -Garden -Recreation
Lack of Exercise
Diet
Alcohol
Hormone Therapy
Benign Breast Disease
???
6
Endocrine disrupting chemicals Definitions

• Endocrine Disrupter
• Exogenous substance or mixture that alters the
  function(s) of the endocrine system and
  consequently causes adverse health effects in an
  intact organism, or its progeny, or
  (sub)populations
• Potential Endocrine Disrupter
• Exogenous substance or mixture that possess
  properties that might be expected to lead to
  endocrine disruption in an intact organism, or
  its progeny, or (sub)populations
• Ref WHO/IPCS, Damstra et al. (eds), Global
  Assessment of the State-of-the Science of
  Endocrine Disruptors, 2002

7
Endocrine disrupting chemicals Possible modes
of action
Breast cancer risk
8
Endocrine disrupting chemicals

• Pharmaceuticals
• Pesticides
• Industrial Chemicals / Contaminants
• Heavy Metals

9
Endocrine disrupting chemicals Ovarian hormones

• Estrogen and progesterone have established roles
  in
• Normal mammary gland development in humans and
  rodent animal models
• Regulation of breast cell proliferation during
  menstrual and estrous cycles
• Humans breast cell proliferation is the highest
  in luteal phase when progesterone levels highest
  progestins do not oppose the action of estrogen
  in the breast
• Ref Haslam et al., J Mammary Gland Biology and
  Neoplasia, 793-105, 2002

10
Endocrine disrupting chemicals Ovarian hormones

• In utero exposure to estrogen associated with
  higher breast cancer risk
• Higher birth weight
• Ref Michels, et al., Lancet, 3481542-46, 1996
• Kaijser et al., Epidemiology, 11315-9,
  2000
• Like-sexed female (dizygotic) twins
• Ref Ekbom et al., J Natl Cancer Inst 8871-6,
  1997
• Cerhan et al., J Natl Cancer Inst,
  92262-5, 2000
• Hubinette et al., Int J Cancer 91248-51,
  2001
• Preeclampsia (lower estrogen, lower risk) Ref
  Ekbom et al., Lancet, 3401015-18, 1992
• Ekbom et al., J National Cancer
  Institute, 8871-6, 1997

11
Endocrine disrupting chemicals Diethylstibestero
l (DES)

• DESHistory of use in women
• Pregnant women treated with DES to prevent
  miscarriages from 1940s to 1971 in US and 1978
  in Europe use continued in unindustrialized
  countries
• Dosage typically 12,000 mg over 4 to 6 months
• DESHistory of use in livestock in US
• Use as growth promoter in feed approved in 1954
• Ear implants approved in 1955
• Use in premixes revoked in 1972 because of
  detection of residues in edible tissues after
  slaughter
• Use in livestock revoked by US Food and Drug
  Administration in 1978 / 1979
• Ref Calle et al., Am J Epidemiology,
  144645-52, 1996
• DHEW, US FDA Judge Davidson brief, 1978
• Huckell et al., Lancet, 348331-1996

12
Endocrine disrupting chemicals Diethylstilbestro
l (DES)

• Human breast cancer risk DES mothers
• First Author Year RR 95 CI Type of
  study
• Greenberg 1984 1.40 1.10-1.90
  Incidence
• Colton 1993 1.35 1.05-1.74
  Incidence
• Calle 1996 1.34 1.06-1.69
  Mortality
• Titus-Ernstroff 2001 1.27 1.07-1.52
  Incidence

13
Endocrine disrupting chemicals Diethylstilbestro
l (DES)

• Premenopausal breast cancer risk DES Daughters
• First Author Year RR 95 CI Years
  Follow-up
• Huckell 1996 Reported 2 cases (28, 34
  years of age)
• Hatch 1998 1.18 0.56 - 2.49 16 years
• Palmer 2002 1.4 0.7 - 2.6 19
  years
• Palmer 2002 2.5 1.0 - 6.3 in women
  over 40
• Palmer 2002 1.9 0.8 - 4.5
  in ER positive tumors

14
Endocrine disrupting chemicals Post-menopausal
hormone use

• Effects on breast cancer risk
• First Author Year E RR 95 CI
  EP RR 95 CI
• Stanford 1995 0.4 0.20-1.0
• Ross 2000 1.06 0.97-1.15 1.24
  1.07-1.45
• Schairer 2000 1.20 1.00-1.4 1.40
  1.10-1.80
• Colditz 2000 1.23 1.06-1.42 1.67
  1.18-2.36
• Chen 2002 1.17 0.85-1.60 1.49
  1.04-2.12
• WHI 2002 1.26 1.00-1.59
• Porch 2002 0.96 0.65-1.42 1.37
  1.05-1.78
• Most studies based on 4-5 years current or recent
  use
• Colditz-Risk at 70 years of age after 10 years
  of use from 50-60 yrs of age

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Post-menopausal hormone use Breast cancer
risk, Nurses Health Study
HRT, Estrogen Prog., 10 yrs
ERT, Estrogen unopposed, 10 yrs ERT, Estrogen
unopposed, 5 yrs Non-users, solid line
Ref Colditz and Rosner, American J Epidemiology,
152950-964, 2000
16
Endocrine disrupting chemicals Post-menopausal
hormone use

• Nurses Health Study
• Ref Porch et al., Cancer Causes Control,
  13847-854, 2002
• PMH use in 17,835 women aged gt 45 years, followed
  for 5.9 yrs
• PMH use E RR 95 CI EP RR 95
  CI
• 0.96 0.65-1.42 1.37 1.05-1.78
• lt 5 yrs 0.96 0.58-1.58 1.11 0.81-1.52
• gt 5 yrs 0.99 0.65-1.53 1.76 1.29-2.39
• Progestin pattern
• lt2 wks/month 1.04 0.74 -1.46
• Continuous 1.82 1.34 -2.48
• Breast cancer risk increased in women who used
• Estrogen-progestin PMH therapy for 5 years or
  more
• Continuous rather than cyclic progestin
  combinations

17
Organochlorines and breast cancer risk Strength
of the evidence

• DDE and DDT
• Early descriptive studies and one case-control
  study suggested a positive association between
  blood / adipose tissue DDE levels and breast
  cancer risk
• Majority of recent, well controlled cohort and
  case-controlled studies have not demonstrated
  that levels of DDE predict breast cancer risk in
  white, western, North American or European white
  women
• Ref Snedeker, Environmental Health Perspectives,
  109(suppl 1)35-47, 2001
• WHO/IPCS, Damstra et. al. (ed) Global
  Assessment EDCs, 2002

18
DDT and DDE commentary Possible explanations
for lack of an association

• Chemical formulation
• In white western women, predominate exposure may
  not be to estrogenic o,p-DDT found in the
  insecticide, but to the very weakly estrogenic,
  anti-androgenic breakdown product, p,p-DDE found
  as residues in food
• Heavily exposed populations not well studied
• Predominate use of DDT in the US was on cotton in
  the south-eastern. One study of African Americans
  women from North Carolina suggests positive
  association of DDE and breast cancer risk
• Few studies of breast cancer risk in countries
  that currently use DDT for malaria control
• Critical windows of exposure need evaluation
• Little information on whether exposure to DDT
  during early breast development affects breast
  cancer risk

19
Organochlorines and breast cancer risk Dieldrin

• Breast cancer risk, equivocal evidence
• Danish studies, Copenhagen City Heart Study
• 1) Serum dieldrin associated with breast cancer
  risk
• OR 2.05, 95CI 1.17-3.57
• Ref Høyer et al., Lancet, 352,
  1816-20,1998
• 2) Serum dieldrin, p53 mutation status breast
  cancer risk
• OR 3.53, 05 CI 0.70-15.79
• Ref Høyer et al., Breast Cancer Research and
  Treatment, 7159-65, 2002
• American studies, no significant association
• OR 0.6, 95 CI 0.3-1.3, Cohort of Missouri
  women
• Ref Dorgan et al., Cancer Causes Control
  101-11, 1999
• OR 1.37, 95 CI 0.60-2.72, Long Island
  Breast Cancer Study
• Ref Gammon et al., Cancer Epidemiology
  Biomarkers Prevention,
• 11686-697, 2002

20
Organochlorines and breast cancer risk Dieldrin

• Breast cancer survival rates and dieldrin levels
• Danish studies, Copenhagen City Heart Study
• 1) Breast cancer survival and serum dieldrin
• RR 2.78, 95 CI 1.38-5.59
• Higher rate of death associated with highest
  blood dieldrin levels
• Ref Høyer et al., J Clinical Epidemiology,
  53323-330, 2000
• 2) Investigated influence of Estrogen Receptor
  (ER) status and serum dieldrin on breast cancer
  survival
• ER RR 2.2, 95 CI 0.9-5.4
• ER- RR 1.8, 95 CI 0.3-5.5
• Risk of dying not significantly elevated in
  those with higher serum dieldrin levels,
  regardless of ER status
• Ref Høyer et al., BMC Cancer 18, 2001
  http//www.biomedcentral.com/1471-2407/1/8

21
Organochlorines and breast cancer
risk Industrial chemicals

• Total polychlorinated biphenyls (PCBs)
• Little evidence of increased breast cancer risk
• Polymorphisms, Gene-environment interaction
• Higher BC risk in sub-group of white American
  women with elevated PCB levels AND variant in
  CYP1A1
• Ref Moysich et al., Cancer Epidemiology
  Biomarkers Prevention,
• 8414-4, 1999
• Individual PCB congeners
• Difficult to evaluate estrogenic congeners dont
  predominate
• Some evidence of increased BC risk with congeners
  that bind to Ah receptor (mono-ortho-substituted)
• Ref Demers et al., American J Epidemiology,
  155629-35, 2002
• Possible association with poorer prognosis
• Association with larger, poorer grade breast
  tumors
• Ref Woolcott, et al., Cancer Causes
  Control,12395-404, 2001

22
Endocrine disrupting chemicals Industrial
chemicals

• Polybrominated diphenyl ethers (PBDP)
• Uses - Flame retardant in plastics, textiles,
  carpets and furniture foam
• Production - 40,000 tons / yr globally (1990)
• Dietary intake - Nordic areas, 0.2-0.7
  micrograms/day
• Ecology
• Detected in marine life globally
• Evidence of human breast milk contamination
• Detected in air, drinking water, as food residues
• Refs Darnerund et al, Environmental Health
  Perspectives, 109(suppl 1)49-68, 2001
• Christensen and Platz, J Environmental
  Monitoring, 3543-7, 2001
• She et al., Chemosphere 46697-707, 2002
• McDonald, Chemosphere 46745-55, 2002
• Wenning, Chemosphere 46779-96, 2002

23
Endocrine disrupting chemicals Industrial
chemicals

• Polybrominated diphenyl ethers (PBDP)
• Evidence of estrogenicity
• Stimulates ER-dependent gene expression in human
  T47D breast cancer cells
• Induces cell proliferation in estrogen-dependent
  MCF-7 breast tumor cell line
• Estrogenicity of PBDEs decreased as bromination
  increased
• PBDPs agonists for both ER-a and ER-b
• Refs Samuelsen et al., Cell Biology and
  Toxicology, 17139-51, 2001
• Meerts et al., Environmental Health
  Perspectives, 109399-407, 2001

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Endocrine disrupting chemicals Occupational
exposures

• ED Chemical Probable exposure
• BC Cases Controls
• Nonylphenol 21.5 21.4
• Butylbenzylphthalate (BBP) 10.0 13.2
• BHA 7.3 9.6
• Bisphenol A 9.6 11.6
• No significant increases in breast cancer risk
• PCBs, OR 3.2, 95 CI 0.8-12.2
• 4-octylphenol, OR 2.9, 95 CI 0.8-10.8
• Ref Aschengrau et al., American J Industrial
  Medicine, 346-14, 1998

25
Endocrine disrupting chemicals Household
levels, Cape Cod study

• Silent Spring Institute
• Developed methodology to assess levels of
  pesticides,bisphenol A,
• alkylphenols, PAHs, and PCBs in air and dust of
  residences
• (microgram/g dust)
• Chemical No Detect/No Anal Range Mean
• DEHP 6/6 69.4-524.0 315.0
• BBP 6/6 12.1-524 184.0
• Carbaryl 2/6 27.2-140 83.6
• Chlorpyrifos 3/6 1.26-89.5 30.7
• Bisphenol A 3/6 0.25-0.48 0.4
• 4-Nonylphenol 4/6 2.3-7.82 4.3
• Benzo(a)pryrene 5/6 0.45-10.6 2.9
• Ref Rudel et. al., J Air Waste Management
  Assoc., 51 499-513, 2001

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Endocrine disrupting chemicals Effects on early
breast development

• Premature Thelarche in Puerto Rico (PR)
• Over 5,000 cases of premature thelarche in the
  last 30 years (breast development lt 8 yrs of age)
  
• Suspect list
• Waste stream from OCA factories
• Hormones residues in food
• Ovarian cysts
• Use of soy formula
• DEHP (phthalate)
• Ref Freni-Titulear et al., Am. J. Dis. Children,
  1401263-67, 1986
• Colon et al., Environmental Health
  Perspectives, 108895-900, 2000

27
Endocrine disrupting chemicals Phthalates
and Premature Thelarche in Puerto Rican Girls
Average conc. in serum, ppb
Phthalate esters
Ref Colon et al., Environmental Health
Perspectives, 108895-900, 2000
28
Endocrine disrupting chemicals Premature
thelarche and breast cancer risk

• More questions than answers
• Does occurrence of premature thelarche in girls
  affect the window of susceptibility of the
  developing breast to chemical carcinogens?
• Do endocrine disrupting chemicals have a role in
  influencing early breast development?
• Research needs
• Linkage studies needed between girls with
  premature thelarche and incidence of breast
  cancer
• Studies needed to assess whether endocrine
  disrupting chemicals can influence the onset of
  breast development

29
Endocrine disrupting chemicals Industrial
contaminants

• Dioxins
• Seveso Italy, 1976 industrial accident
• Breast cancer mortality females,1976-86
• RR 0.64, 95CI 0.4 - 0.9 (less than expected)
• Ref Bertazzi et al., Am J Epidemiology,
  1291187-1200, 1989
• Seveso Womens Health Study
• -Cohort of 981 women, infants to 40 yrs of age
  in 1976, resided in area of highest TCDD exposure
• -Preliminary data those with highest exposures
  had higher breast cancer risk (15 cases)
• Ref Warner et al., Environmental Health
  Perspectives, 110625-628, 2002

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Endocrine disrupting chemicals -Cellular targets
for carcinogens
Mammary gland structures in the 35-day old CD-1
female mouse

• Terminal End Bud
• (TEB)
• Alveolar Buds

Photo Snedeker and DiAugustine, 1988
31
Endocrine disrupting chemicals -Understanding
susceptibility
Human breast development
E2 Growth Hormone IGF
Ref Russo and Russo, Oncology Research,
11169-178, 1999
32
Endocrine Disrupting Chemicals -Influencing the
window of susceptibility

• Possible ways in utero or pubertal exposures to
  EDCs may affect breast cancer risk
• Affecting the expression of hormone or growth
  factor receptors, and hormone responsiveness of
  the mammary gland
• Lengthening the window of susceptibility by
  affecting mammary gland development
• Persistence of terminal end buds
• Influencing differentiation

33
Endocrine Disrupting Chemicals -Influencing the
window of susceptibility

• Dioxin - TCDD effects on mammary gland
• TCDD affects ER- a expression
• Gestational-lactation exposure to TCDD in rats
  causes an increase in ER-a expression levels and
  impaired differentiation in mammary glands of
  female pups
• Ref Lewis et al., Toxicological Sciences,
  6246-53, 2001
• TCDD affects cancer susceptibility
• Gestational exposure to TCDD causes persistency
  of TEB structures in female pups, delayed vaginal
  opening, and an increase in chemically induced
  (DMBA) mammary adenocarcinomas
• Ref Brown et al., Carcinogenesis, 191623-1629,
  1998
• TCDD permanently affects mammary gland
  development
• Normal mammary gland transplanted into fat pads
  of TCDD treated female rats grows at a slower
  rate and appeared underdeveloped TCDD may affect
  development of stroma
• Ref Fenton et al., Toxicological Sciences,
  6763-74, 2002

34
Endocrine disrupting chemicals Heavy metals

• Cadmium (Cd), possible estrogenic effects
• Interacts with estrogen receptor-alpha (ER-a)
  MCF-7 cells
• Cd binds to ER-a, and blocks binding of estradiol
  to ER-a
• Interacts with hormone binding domain of ER-a
• COS-1 cells cotransfected with GAL-ER and GAL4
  reporter gene
• Treatment with either Cd or estradiol increased
  reporter gene activity four-fold
• ER-a mutants used to identify interaction sites
  of Cd with ER-a hormone binding domain
• In vivo effect on rodent mammary gland
• Promotes growth, differentiation and side
  branching of MG in ovariectomized animal
• In utero exposure earlier onset of puberty
  altered MG development
• Refs Garcia-Morales et al., J Biological
  Chemistry, 26916896-901, 1994
• Stocia et al., Molecular Endocrinology,
  14545-553, 2000
• Maritin, MB, abstract, e_hormone 2001,
  Tulane University

35
Endocrine disrupting chemicals Heavy metals

• Arsenite, possible estrogenic effects
• Interacts with estrogen receptor-alpha (ER-a)
• MCF-7 breast cancer cells treated with arsenite
• Decreased level of ER-a and ER-a mRNA
• Increased concentration of progesterone receptor
  (PR)
• Arsenite-induced increase in PR blocked by
  antiestrogens
• Arsenite blocked binding of estradiol to ER-a
• Stimulates proliferation in MCF-7 cells
• Arsenite stimulated proliferation of MCF-7 cells
  in estrogen depleted medium effect blocked by
  antiestrogens
• Interacts with hormone binding domain of ER-a
• COS-1 cells transfected with GAL-ER and CAT
  reporter
• Arsenite or estradiol treatment induced CAT
  activity
• ER-a mutants used to identify interaction sites
  of arsenite with ER-a hormone binding domain
• Ref Stocia et al., Endocrinology,
  1413595-3602, 2000

36
Endocrine disrupting chemicals Current
challenges

• Complexity of breast cancer
• Long latency
• Many established risk factors
• Risk influenced by interaction of genetic
  alterations, susceptibility and proliferative
  state

37
Endocrine disrupting chemicals Current
challenges

• Exposure issues
• Difficult to characterize and measure low-level
  exposures to multiple chemicals from the distant
  past
• Few chemicals have validated biomarkers
• Levels of exposure to EDCs at critical periods of
  breast development (in utero through puberty) is
  lacking
• Exposures to EDCs in the home environment not
  well characterized

38
Endocrine disrupting chemicals Current
challenges

• Modeling issues
• May be difficult to evaluate effects of low-level
  exposures to multiple chemicals using
  epidemiology
• Animal modeling should include promotional models
  to assess effects of EDCs that may influence
  growth of established hormone-dependent tumors
• Estrogenicity should not be the sole endpoint for
  EDC breast cancer risk evaluation other
  hormones, growth factor agonists, and chemicals
  that affect mammary gland development should be
  evaluated