Management of higher risk of colorectal cancer Huw Thomas
Colorectal Cancer 41,000 new cases pa in UK 16,000 deaths pa 60% 5 year survival Adenoma-carcinoma sequence (Morson) Survival vs stage (Dukes)
Bowel Cancer Screening Programme Population risk One first degree relative >50 years of age One-off flexible sigmoidoscopy aged 55 Bi-annual FIT from 60 70 years of age Colonoscopy if positive FIT
Higher risk groups Inherited conditions Polyposis syndromes Lynch syndrome Family history CRC Inflammatory Bowel Disease
Surveillance higher risk groups One-off colonoscopy aged 55 Five yearly colonoscopy from age 45 Biannual colonoscopy from age 25
Defining Risk Recognition clinical syndromes Lynch syndrome tumour testing Family history questionnaire
Familial Risk of CRC Enviromental Hamartomatous syndromes < 0.1% FAP < 1% Lynch 2-3% Familial 30%
Familial adenomatous polyposis Autosomal dominant Colonic adenomas >100 Colorectal cancer 10% no family history Extra-colonic features
Lynch syndrome Inherited alteration of DNA mismatch repair genes An increased risk of colorectal and other tumours Tumours are diploid with microsatellite instability cf Hereditary nonpolyposis colorectal cancer (HNPCC)
Lynch syndrome genes MLH1 PMS2 (complex with MLH1) MSH2 MSH6 (complex with MSH6) (EPCAM)
Lynch syndrome phenotype Autosomal dominant No polyposis Early age onset cancers Colorectal cancers predominantly rightsided Endometrial, ovarian, small bowel, ureter or renal pelvis
Lifetime risk to age 70 Colorectal 35% Endometrial 34% Ovarian 8% Gastric 0.7% Urothelium 1.9% Small bowel 0.6% Biliary tract 0.6% Bonadona et al 2011
LS Gene-specific lifetime risk
Lynch syndrome tumour testing NICE guidance All CRC to be tested Mainstreaming genetic testing
CaPP 2 / 3 Aspirin chemoprevention
Management of familial risk Ascertainment of family history Family history questionaire Cancer registry / histopathology reports Assessment of risk Surveillence protocol
Moderate familial risk of CRC Amsterdam criteria families non MSI tumours (approx 50%) 3 FDR CRC none diagnosed <50 years 2FDR CRC 1FDR CRC diagnosed <45 years Gene(s) responsible yet to be identified
St Mark s Family Cancer Clinic colonoscopic surveillance 1678 individuals flagged NHS CR 15,000 patient-years of follow-up Initially 5yearly colonoscopy, 3yearly if adenomas AC Moderate risk (<45) High-risk adenomas 5.0% 1.7% (1.1%) Cancer 1.0% 0.1% (0%) Reduced incidence Ca 43% 80%
Colonoscopic surveillance in HNPCC and dominant pedigrees HNPCC Dominant Proband AC/3FDR MSI non MSI 91 208 Adenomas 18.7% 18.8% Multiple Ad 0% 4.8% HR adenomas 7.7% 9.1% Cancers 4.4% 0.48% St Mark s and NFDHT Leiden
Surveillance with moderate familial risk One 1 o relative <45yrs Two 1 o relatives av.age <60 yrs Three relatives age >50 yrs Colonoscopy from 40-45yrs 5 yearly if clear 3 yearly if adenomas
Surveillance lesser familial risk Two 1 o relatives average age <70 1 o and 2 o relative (same side family) average age < 70 Single colonoscopy aged 55
Surveillance with one affected relative One 1 o relative > 45 yrs As for population risk
BSG Guidance for moderate familial risk One 1 o relative <45yrs Two relatives one <55 yrs Three relatives CRC or one endometrial Single colonoscopy aged 30-35 If normal repeat aged 55 Dunlop 2002
Inherited predispositions to colorectal cancer Mendelian dominant Familial adenomatous polyposis Lynch syndrome Mendelian recessive MYH associated polyposis Rare variants- low penetrance e.g. APC T3920A Common low penetrance variants Genome-wide association studies
Inherited Colorectal Cancer Syndromes Early age onset Dominant or Recessive Inheritance Polyps or Polyposis
Oligocryptal adenomas
Adenomatous polyposis coli gene APC is a tumour suppressor gene Second hit inactivates normal allele Wnt pathway (Myc) Occurs early in tumourigenesis (adenoma) Aneuploid tumours Same pathway frequent in sporadic CRC
APC genotype:phenotype Polyposis Attenuated Polyps truncating mutations 3 and 5 mutations point mutations (eg T3920A) Gardner s Turcot s osteomas, epidermoid cysts medulloblastomas
APC T3920A Ashkenazi Jewish founder mutation AAATAAAA to (A) 8 Creates unstable poly A tract Somatic mutations during replication Adenomatous colonic polyps OR 2-3 colorectal cancer Laken et al 1997
Management of FAP Referral to genetic /polyposis registry Surgical management of proband Surveillance of at risk family (dye spray) Genetic testing?role aspirin / COX 2 inhibitors
Genetic diagnosis of LS Young or multiple cases of LS cancers in family Histopathology of MSI tumours Tumour testing for loss of expression MMR genes and MSI NICE guidance IHC all CRCs < 70 yrs
Screening for Lynch syndrome 1066 patients CRC Columbus Ohio 208 (19.5%) MSI 23 (2.2%) mutations causing Lynch syndrome 10 >50 years of age 3 fulfilled AC 5 did not meet AC or Bethesda Hampel et al NEJM 2005;352: 1851-60
Management of Lynch syndrome Identification at-risk family members Colonoscopic surveillance Presymptomatic genetic testing? Surveillance associated cancers Chemoprevention studies Preimplantation genetic testing
CAPP 2 Chemoprevention Trial in Lynch syndrome Aspirin (and Resistant starch) 937 participants factorial design No difference cancer incidence at 2 years 55 months per protocol analysis CRC HR 0.45 (CI 0.22-0.93) LS non CRC HR 0.49 (CI 0.23-1.05) Burn B at al 2009 / 2011
Hamartomatous polyposis syndromes Peutz Jeghers LKB1 Juvenile Polyposis SMAD4 (20%) BMPR1A (20%) Cowden s PTEN Hereditary mixed P S GREM1
Peutz Jeghers pigmentation
Juvenile polyp
Familial risk of colorectal cancer <5% CRC dominant inheritance Scandanavian Twin Studies 35% risk of colorectal cancer attributable to heritable factors (Lichenstein et al 2000)
MYH associated polyposis Autosomal recessive DNA base excision repair gene Repairs oxidative damage to DNA G:C-> A:T transversions Multiple adenomas in bi-allelic genecarriers Transversions in tumour DNA
Base excision repair of oxidative DNA damage Oxidative DNA damage MTH1 8-oxoG OGG1 N N N G N N N N N N A N N N MutYH
MYH pedigree
Genetic pathways colorectal tumourigenesis Chromosomal instability (85%) APC gene mutations Aneuploid tumours Microsatellite instability Methylation MLH1 gene promotor Diploid Tumours
Next-generation / Parallel DNA Sequencing Detection of single fluorescent bases as they are incorporated into growing DNA strand Massive parallel sequencing Long and short reads Illumina Sequencing by Synthesis (SBS)
Next-generation / Parallel DNA sequencing Germline whole-genome sequencing for new inherited genes Tumour exome or whole-genome sequencing for genetic pathways Intra- tumour sequencing for tumour evolution Diagnostic gene panels
Oxford-Illumina WGS500 project 15 probands with at least 10 adenomas by 60 years of age and personal or family history CRC 5 additional affected family members 5 families from St Mark s Whole genomes sequenced from constitutional DNA on Illumina platform
Overall Results 10,000 coding region variants with potential effects on protein sequence per person Known pathogenic mutations APC x3 MSH6 x 1 No obvious candidates? Heterogeneity
POLE and POLD1 Mutations proofreading domains DNA polymerase epislon and delta Defect in correction of mispaired bases inserted during DNA replication Tumours microsatellite stable Large numbers of base substitutions
Polymerase Proofreadingassociated Polyposis (PPAP) Multiple colorectal adenomas Early-onset colorectal cancer Duodenal adenomas and carcinomas POLD1 endometrial cancers? Accelerated tumourigenesis
The Cancer Genome Atlas Detailed genetic analysis of multiple CRCs
Molecular characterization of human colon and rectal cancer 276 samples Exome sequencing DNA copy number Promoter methylation mrna and microrna expression 97 whole genome sequencing The Cancer Genome Atlas Nature 2012; 487; 330
Non-hypermutable cancers (84%) (chromosome unstable / aneuploid) <1 mutation / 10 6 bases Hypermutable cancers (16%) (microsatellite unstable / diploid) >100 mutations / 10 6 bases
Hypermutated Cancers ¾ hypermethylated MLH1 promoter methylation Microsatellite instability ¼ POLE mutations Microsatellite stable
Genetic heterogeneity within tumours Intratumour heterogeneity and branched evolution revealed by multiregion sequencing Gerlinger et al NEJM 2012; 366: 883
Intra-tumour heterogeneity Multiple spatially separate samples from primary renal cell cancers and associated metastases Exome sequencing, chromosome aberration analysis and ploidy profiling Phylogenetic reconstruction revealed branched evolutionary tumour growth 63-69% somatic mutations not in all tumour regions
Gene Panels Cancer predisposition genes Specific primers for exons Next generation sequencing of products TruSight Panel 97 genes (ICR / Illumina) Select which gene results are analysed
Gene Panels Lynch syndrome phenotype 1260 individuals 25 gene panel DNA mismatch repair genes and EPCAM 114 mutations BRCA 1 and 2 15 mutations Yurgelin et al Gastroenterology 2015; 149; 604
Personalised medicine / Immunotherapy Hypermutable cancers Somatic mutations lead to multiple new non-self immunogenic antigens Tumours characterised by lymphocytic infiltrate Possible targets for immunotherapy Le et al NEJM 2015; 26: 2509
Programmed Death 1 Pathway Th1 lymphocytes cytotoxic immune response to cells displaying non-self antigens PD-1 Immune check point to prevent autoimmunity PD-1 Immune check point up-regulated in many tumours Tumours protected from cytotoxic Th1 cells
PD-1 blockade in MSI tumours MSI tumours large number of somatic mutations and non-self immunogenic antigens Pembrolizumab is an anti-programmed death 1 immune checkpoint inhibitor Assess clinical response MSI colorectal tumours to immunotherapy
Response to Pembrolizumab Metastatic CRC Response rate and progression free survival 10 MSI 40% and 78% 18 MSS 0% and 11% HR disease progression / death 0.1 P<0.001 HR death 0.22 P 0.05 Whole exome sequencing 1782 vs 73 mutations
Mendelian genetic Predispositions Familial Adenomatous Polyposis Lynch syndrome Mut YH associated polyposis
Next Generation Sequencing WGS detect new cancer predisposition genes (cf linkage analysis) WGS genetic pathways in neoplasia WGS branched evolution of tumours Gene panels for diagnosis
Personalised medicine Hypermutable cancers Immunotherapy PD-1 checkpoint inhibitor
Lynch HT and de la Chapelle A Hereditary Colorectal Cancer NEJM 2003; 348: 919-32 The Cancer Genome Atlas. Comprehensive molecular characterization of human colon and rectal cancer. Nature 2012: 487; 330-7
Burn et al. Long-term effect of aspirin on cancer risk in carriers of hereditary colorectal cancer: an analysis from the CAPP2 RCT. Lancet 2011; 378: 2081-7 Palles et al Germline mutations affecting the proofreading domains of POLE and POLD1 predispose to colorectal adenomas and carcinomas. Nature Genet 2013; 45: 136-144
IHC MLH1 MSH2 MSH6 PMS2