Management of carriers of hereditary predisposition to breast cancer Marc Abramowicz Medical Genetics, ULB Centre des tumeurs ULB – Erasme / Bordet

Cancer Genetics In tumors (tumor DNA = somatic DNA) : Molecular pathology; tumorigenesis routes. –Genetic –Epigenetic In patients (constitutional DNA = germ-line DNA) : Cancer risk profiling, from inherited mutations/polymorphisms

10-12% women will develop breast cancer No genetic factor Major genetic factor (high penetrance gene) All breast cancer cases (> 10% women) Minor genetic factor(s)

Hereditary breast/ovarian cancer Genetically heterogeneous –BRCA1 –BRCA2 –Others (?) and extended syndromes: Li-Fraumeni, Cowden, … Penetrance incomplete and age- (and gender-) dependent  50 – 80 %, breast; 15– 60 %, ovary Phenocopies : chance coincidence of cancer in same families No specific cancer phenotype  Br+ov: >80% of multiple familial cases  Br only: >50% of multiple familial cases (Ford et al 1998)

Hereditary breast and ovarian cancer 5-10% of breast cancers are inherited –Familial occurence, mendelian pattern Heterozygous for one single gene –multiples primary tumours –Early onset (mean age, breast: 42 yrs)

Penetrance, BRCA1 – linked breast cancer Struewing et al. 1997, NEJM 336:

Penetrance, BRCA2 – linked ovarian cancer Struewing et al. 1997, NEJM 336:

Penetrance of breast cancer Biased in families ascertained for high incidence of breast cancer Meta-analysis of 10 studies < high-risk clinics and population-based setting Chen & Parmigiani JCO 2007 Cumulative incidence by age 70 95% Confidence Interval BRCA BRCA

Penetrance of breast cancer Biased in families ascertained for high incidence of breast cancer Meta-analysis of 10 studies < high-risk clinics and population-based setting Chen & Parmigiani JCO 2007 But depends on low-penetrance alleles too: some effect of family history even after exclusion of BRCA mutation Cumulative incidence by age 70 95% Confidence Interval BRCA BRCA

BRCA1 ≠ BRCA2 but no difference in clinical care as of today BRCA1 activates transcription of ER gene ESR1 Hosey 2007 J Natl Canc inst BRCA1 required for differentiation of stem cell, and progenitor cell (ER-) into luminal cell : Liu-S et al 2008 PNAS … and other cellular functions Cf: BRCA1 carrier tumors often ER- (75%); many Basal-like type ER-, PR-, HER2- (44%) Lakhani et al 2005 Clin Canc Res BRCA2 carrier tumors mostly ER+ (75%), ductal carcinomas, luminal type Foulkes 2004 Clin Canc Res

GENETIC TESTING AND GENETIC COUNSELING

Genetic analysis BRCA1&2 Labor-intensive (3 months) ; expensive Mutation detection efficacy 70 % –Some mutations in introns, in gene promoters,… –BRCA3 ? Psycho and social impact of testing False +, false -. False reassurance. => Not performed in each patient with breast or ovarian cancer (ASCO 1996; ASCO 2003)

Hereditary breast/ovarian cancer Care management of this patient must include DNA sampling, in order to counsel her daughter appropriately in the future.

DNA analysis and genetic counseling If hereditary cancer plausible (Proba BRCA mutation > 10%) –2 women < 50 yrs (any age if bilateral) (1st degree, 2nd if paternal) –1 breast < 50 yrs + 1 ovary, any age –4 women, breast only –1 woman breast + ovary –1 woman < 35 yrs Test affected relative first. With informed consent. Via genetic counseling. In women with cancer history: –Breast recurrence risk; ovarian risk; family implications In asymptomatic relatives : PGT (Presymptomatic Genetic Testing) –NO SAMPLING AT FIRST VISIT. –Counsel on: Breast risk; ovarian risk; Medical options; Family implications –Psycho support. Anticipate results of PGT, and adjust –Duplicate DNA sampling

DNA analysis and genetic counseling If hereditary cancer plausible (Proba BRCA mutation > 10%) –2 women < 50 yrs (any age if bilateral) (1st degree, 2nd if paternal) –1 breast < 50 yrs + 1 ovary, any age –4 women, breast only –1 woman breast + ovary –1 woman < 35 yrs Test affected relative first. With informed consent. Via genetic counseling. Reassure 50% of first-degree relatives In mutation carriers, provide risk management strategy –optimum = ? –Bilateral prophyllactic ovario-annexectomy:  Ov. Ca risk,  Br.Ca risk,  overall mortality –Prophyllactic radical mastectomy ? –Breast surveillance

* *Mutation tronquante pLys339ArgfsX2 de BRCA1,  Prévoir ovariectomie chez III.4, tester II.4 II.3 K sein 48 ans, DCD 50 II.4 K sein 35 ans, ovaire 51 ans III.4 K sein 39 ans mutation g30877delA pLys339ArgfsX2 de BRCA1

MANAGEMENT OF CARRIERS

Prophyllactic mastectomy in asymptomatic carrier ? Reduces risk by >95% only if total (not subcutaneous) –Rebbeck et al J Clin Oncol 2004 (PROSE study), and references therein No evidence for significant survival benefit as compared with surveillance only –No level 1 evidence, unclear other evidence –Prospective, randomized, 2-blind study unfeasible No effect on ovarian risk. => Only in carefully selected, fully informed, mastectomy-requesting patients => Optimal age for procedure = ?

Age-related penetrance

Bilateral mastec if unilateral cancer in BRCA1or2 carrier ? Reduces by 90% risk of recurrence, ipsi or heterolateral (same as in asymptomatic mutation carrier) Does not reduce mortality as compared with surveillance–only group Van Sprundel et al. Br J Cancer 2005

Guidelines in asymptomatic BRCA1/2 carriers: (1) OVARIES Risk-Reducing Salpingo-Oophorectomy at yrs: –  Ov.Ca risk by >95% Kauff et al 2002 NEJM; Rebbeck et al NEJM; Rutter et al J Natl C Inst; Eisen et al JCO –  Br.Ca risk by 50% if BRCA1 mutation Eisen et al. AJHG 2000; Kauff et al. NEJM 2002; Rebbeck et al. NEJM 2002; –  overall mortality Rebbeck et al. NEJM 2002; Domchek et al. Lancet 2006 But unclear if same benefit in BRCA2 as in BRCA1 (Kauff 2008 JCO)

Guidelines in asymptomatic BRCA1/2 carriers: (2) BREAST Prophyllactic total mastectomy ? Unclear benefit in terms of survival –  Br ca risk by 90% (95% if +RRSO) Rebbeck et al 2004 JCO Breast surveillance: –monthly self-exam? No proven benefit –mammograms ± US Mammograms reduce breast cancer death by 22% after 50 yrs (Humphrey 2002 Ann Int Med) BUT: denser breast / faster doubling size in younger women Ultrasounds improve detection rate (Kuhl 2005 JCO) –clinical breast exam by experienced MD: improves detection in some studies (Warner 2004 JAMA) –MRI (Kriege et al NEJM 2004 ): more Ss, less Sp => likely cost effective if high a priori risk: BRCA1; BRCA2 with dense breasts Tamoxifen? Only BRCA2. Raloxifen, AIs? Unclear (King et al JAMA; Robson & Offit 2007 NEJM)

Guidelines in asymptomatic BRCA1/2 carriers (3) optimum = ? Bilat prophyl salpingo-oophorectomy at yrs: –  Ov.Ca risk by >95% Kauff et al 2002 NEJM; Rebbeck et al NEJM; Rutter et al J Natl C Inst; Eisen et al JCO –  Br.Ca risk by 50% if BRCA1 mutation Eisen et al. AJHG 2000; Kauff et al. NEJM 2002; Rebbeck et al. NEJM 2002; –  overall mortality Rebbeck et al. NEJM 2002; Domchek et al. Lancet 2006 Breast surveillance: monthly self-exam; mammograms ± US; clinical breast exam. MRI. ( Kriege et al NEJM 2004 ) Prophyllactic total mastectomy ? Unclear benefit => only in carefully selected, fully informed patients

Trends Identify low-penetrance alleles Risk profiling ? Targeted prevention ? Pathway-specific therapies Pharmacogenetics

SOME MOLECULAR DATA

Major (monogenic) hereditary predisposition to breast cancer Robson & Offit 2007

Major (monogenic) and minor (polygenic) hereditary predisposition to breast cancer Robson & Offit 2007

A cellular pathway of DNA repair and chromosome integrity Walsh & King 2007 Cancer cell

What does this teach us? Low penetrance alleles modulate high-penetrance genes (eg Antoniou 2008 AJHG) BRCA1 deficient cell lines are sensitive to Xrays; Etoposide; Bleomycin: double-strand DNA breaks, and Platinum drugs: DNA cross-links => platinum clinical trials in BRCA1-deficient tumor patients

What does this teach us? Low penetrance alleles modulate high-penetrance genes (eg Antoniou 2008 AJHG) BRCA1 deficient cell lines are sensitive to Xrays; Etoposide; Bleomycin: double-strand DNA breaks, and Platinum drugs: DNA cross-links => platinum clinical trials in BRCA1-deficient tumor patients Poly-ADP-ribose polymerase (PARP) required at initial step of DNA repair => PARP inhibitors in BRCA1 or 2-deficient tumor patients

LOW-PENETRANCE ALLELES

Majority ? of breast cancers Some susceptibility stems from combination of several genes, each with low penetrance –Twin studies: concordant MZ ~25% (Ahlbom et al 1997 JNCI; Baker et al 2005 Biometrics) –SNPs; CNVs (?); polygenic –A few genes known in 2008… more data are coming CHEK2, ATM, PALB2, BRIP1; …, FGFR2, –Some of the same genes modify severity of BRCA1&2 course –No routine testing Environment (hormones, diet, other factors) Epigenetic effects? Already in utero ??

Families with > 4 cases of breast cancer The most important conclusion from this analysis is that a large proportion, perhaps the majority, of families with five or fewer cases of breast cancer and no ovarian or male breast cancer cases are not due to either BRCA1 or BRCA2. Am J Hum Genet 62:676-9, 1998

Familial breast cancer: cases controls Collaborative group, Lancet 358: , 2001 Most women with breast cancer have no affected relative; most women with affected relatives will not develop br ca. If cancer, not at young age. Age of relative at Δ has little effect.

Trends Identify low-penetrance alleles Risk profiling ? Targeted prevention ? Pathway-specific therapies Pharmacogenetics

Age-related penetrance