1. www.DebbiesDream.org Raising Awareness. Funding Research.
Supporting Patients. Achieving the DREAM!

2. Epidemiology and Genetics of Gastric Cancer
New York Stomach Cancer Education Symposium
Epidemiology and Genetics
of Gastric Cancer
Lecturer – Manish A. Shah, MD
The Bartlett Family Associate Professor of Gastrointestinal Malignancies
Director, Gastrointestinal Oncology Program
Co-Director, Center for Advanced Digestive Care
Weill Cornell Medical College/ New York-Presbyterian Hospital
Debbie’s Dream Foundation Medical Advisory Board Member

3. Esophageal and Gastric Carcinoma US Incidence in 2016
U.S. : 43,280 new cases (2.6% all U.S. cancers)
Gastric: 26,370 (61%)
Esophagus: 16,910 (39%)
Decline in Gastric Cancer Incidence
Increase in Esophageal , GE JX, cardia adeno
OS improvement, , ,
Gastric: 16%  18%  27%
Esophageal: 5%  10%  19%
Siegel RL et al., CA Cancer J Clin. 2016; 66:7-30

4. Risk Factors for GI Cancer
Diet
Alcohol
Hot drinks
Tobacco smoking
Acid reflux
Obesity
H. Pylori
Atrophic gastritis
Esophagus
GE, gastroesophageal.
—proximal nondiffuse, diffuse, and distal nondiffuse gastric cancer. + adeno oesophageal – Manish Shah
Gastroesophageal junction
Cardiac sphincter
Liver

5. Factors Associated With Increased Risk of Developing Stomach Cancer
Nutritional/environmental
Salted or smoked foods
High dietary nitrates
Low intake of fruits, vegetables, and vitamin A and C consumption
Low serum selenium
Social
Low socioeconomic status
Tobacco use
Medical
Prior gastric surgery
Helicobacter pylori infection
Cag-1
Gastric atrophy and gastritis
Pernicious anemia

6. Hereditary Diffuse Gastric Cancer
Caused by germline mutation in CDH1, E-cadherin
Cell-adhesion protein critical to development, cell differentiation, and cell architecture
60-80% penetrance
Prophylactic gastrectomy – numerous in situ foci of signet ring cell adenocarcinoma

7. E. Cadherin/ Beta-catenin/ Wnt
The E. Cadherin/ Beta-catenin/ Wnt signaling pathway
Truncating mutation is
responsible for DHGC
~ 2- 20% of
sporadic diffuse
GC have CDH1
mutations.

8. Criteria for testing for E-cadherin gene mutation
Updated recommendations from the International Gastric Cancer Linkage Consortium (IGCLC)*
Two or more documented cases of gastric cancer in first degree relatives, with at least one documented case of diffuse gastric cancer diagnosed before the age of 50 years
2. Three or more cases of documented diffuse gastric cancer in first- or second-degree relatives, independent of age of onset
3. Diffuse gastric cancer before the age of 40 years without a family history
4. Families with diagnoses of both diffuse gastric cancer and lobular breast cancer, with one case before the age of 50 years
*In addition, in cases where expert pathologists detect carcinoma in situ adjacent to diffuse-type gastric cancer, genetic testing should be considered since this is rarely, if ever, seen in sporadic cases.
Fitzgerald R et al:J Med Genet 47: , 2010

9. Disease Heterogeneity
Gastric and Esophageal Cancers are not one disease.
Esophagus
Histology (squamous v adeno)
Etiology (tobacco/EtOH v HPV)
Gastric
Histology (Intestinal vs Diffuse)
Location (Cardia/GEJ vs Antrum)
Biology (MET, CDH1, others?)
Etiology (H. pylori related, others?)

10. Helicobacter pylori
Robin Warren
Barry Marshall

11. Helicobacter pylori
Endemic infection present ~half of all humans. Particularly prevalent in developing countries
Gram-negative bacteria that infects the antrum mucosa lining of the stomach leading to increase in pH levels
Causes chronic gastritis, gastric ulceration, and gastric atrophy
World Health Organization class-I carcinogen

12. Proximal vs Distal Gastric Cancer
Two Distinct Patterns
Cardia/ GEJ Cancers
Male: Female (5:1)
white: black (2:1)
wide age range
industrialized nations
Non-Cardia Cancers
Male: Female (2:1)
white: black (1:4)
incidence increases with age (peak age 50-70)

13. Epidemiology Summary Wide variation in global incidence
Diet, lifestyle, H. pylori
Falling incidence of gastric and squamous cancer
Barrett’s/esophageal carcinoma
Rising incidence
Screening strategies being studied
Needs better markers to predict risk of progression
Knowledge of the molecular drivers will lead to new therapies.

14. GC Genetic Predisposition Syndromes
Genetic Considerations
GC Genetic Predisposition Syndromes
Account for 10% -15% of all Gastrointestinal Cancers
Hereditary Diffuse GC (~3-5%)
Lynch Syndrome (~1-2%)
germline mutations in one of the mismatch repair genes MLH1, MSH2, MSH6, and PMS2
Stomach cancers occur in ~11% of Lynch syndrome families
FAP (Familial Adenomatous Polyposis) (~1%)
Germline mutation in APC – adenomatous polyposis coli
Fundic gland polyps
Li Fraumeni’s syndrome (< 1%)
p53 mutation
Peutz-Jeghers syndrome (<1%)
Autosomal dominant, hamartomatous polyps of GI tract and mucocutaneous melanin deposits
Germline mutations in STK11 – serine threonine kinase 11.

15. Genetic Considerations
Disease Heterogeny
Global Heterogeneity
More prevalent in Asia
H. pylori variance
More advanced disease in US, West.
Different underlying biology?
Upper GI Cancers cannot be treated as one disease.
Histology (Intestinal vs Diffuse)
Location (Cardia/GEJ vs Antrum)
Biology (MET, CDH1, others?)
Etiology (H. pylori related, others?)

16. Carcinogenesis Conceptual Model Distal non diffuse Gastric CA Genetic
Immune SNPs
IL1, IL4, etc.
Distal non diffuse
Gastric CA
Family History
CDH1
MMR
APC
TP53
Genetic
Risk
Environment
H. Pylori
cag A strain
Behavior
Proximal non diffuse
Gastric Cancer
Diffuse Gastric CA
Tobacco use/ diet (salt) (fruits/vegetables )

17. Prevalent Risk Factors (estimated OR)
Disease Types
Gastric Cancer
Subtype
Prevalent Risk Factors (estimated OR)
Non-Cardia
Environmental
High dietary salt
Eating Fruits / Vegetables (OR ~0.7)
Tobacco (OR ~1.5)
Age (peak at age 50-70)
Clinical
H. pylori infection (OR ~3.0)
Use of NSAIDs/ Aspirin
Genetic
Immune regulatory SNPs
Diffuse
none specifically identified ?
CDH1 mutation
Family history (non- CDH1 mutant)
Proximal
Tobacco Use
Alcohol
Obesity/ High BMI
GERD
Shah and Kelsen, JNCCN 2010

18. Disease Types
Gastric cancer subtypes each differ significantly from normal and from each other. Type 1=proximal Type 2=diffuse Type 3=distal False Discovery Rate=5% Fold Change > 2.0
Probes that are significantly different between NORMAL stomach and GC subtype

19. Molecular evidence for 3 types of gastric cancer
Data
Molecular evidence for 3 types of gastric cancer
36 microarrays (15 of type 1, 13 of type 2 and 13 of type 3).
All arrays were processed using Bioconductor R-package.
To perform supervised classification, pdmclass R-library was used that implements ridge regression with the optimal scoring algorithm
CONCLUSION: Samples from different gastric cancer subtypes are quite well separated and very tightly grouped.
Distal/
intestinal
Proximal/
GEJ
Diffuse
> 85% prediction
Shah et al Clin Cancer Res 2011;17:

20. Data Genomic Data Tan et al Gastroenterology 2011
Expression analysis of 37 gastric cancer cell lines
4 independent patient cohorts (n = 521 patients)
Identified a 171-gene set which robustly classifies tumors into predominantly intestinal and diffuse GC subtypes.

21. Unsupervised Cluster Analysis
Data
Unsupervised Cluster Analysis
Two major types of
Gastric cancer:
G- INT - Blue
G- DIF - Red
A. Hierarchical dendogram
B. Silhouette widths of
individual cell lines
C. Heat map

22. Two major GC signatures: association with Lauren’s subtype
Data
Gastric Cancer Subtypes
Two major GC signatures: association with Lauren’s subtype

23. Molecular Subtypes of GC and Key Features
The Cancer Genome Atlas Research Network, Nature. 2014;513:

24. Four Genomic Subsets Emerge: Genome Atlas
Genomically unstable (50%)
Intestinal, present in most GEJ tumors
High rate of p53 mutation, amplification of RTK’s
High rate of microsatellite instability (MSI), gene mutation, and promoter hypermethylation (22%)
Genomically stable (20%)
Associated with diffuse histology, CHD-1 and RHOA mutation
High Epstein-Barr virus burden (9%)
High rate of PIK3CA mutation, PD-L1 and 2 amplification, strong IL-12 signaling indicating an immune presence
The Cancer Genome Atlas Research Network., Nature. 2014;513:

25. Current Disease Paradigm
Proximal non diffuse Gastric Ca
- Chromosome Instable
EBV Associated Gastric Ca
Immune SNPs
IL1, IL4, etc.
Family History:
CDH1
MMR
APC
TP53
Genetic
Risk
Environment
H. Pylori (cag A strain)
EBV
Behavior
Distal non diffuse Gastric CA
Chromosome Instable
MSI
Diffuse Gastric CA
Genomically Stable
Tobacco use/ diet (salt) (fruits/vegetables)
The Cancer Genome Atlas Research Network, Nature. 2014;513:

26. PD-L1 and PD-L2 Expression Are Elevated in Gastric Cancer
PD-L1 (CD274) 7 6 5 4 3 2 1
mRNA Expression (RNA Seq RPKM)(log2)
CIN
EBV GS
MSI
Molecular Subtype
PD-L2 (PDCD1LG2)
3.5
3.0
2.5
2.0
1.5
1.0
0.5
mRNA Expression (RNA Seq RPKM)(log2)
CIN
EBV GS
MSI
Molecular Subtype
CIN = chromosome instability; EBV = Epstein-Barr virus; GS = gnomically stable; MSI = microsatellite instability.
Bass A. Comprehensive molecular characterization of gastric cancer. Presented at: TCGA Symposium, May 13, 2014.

27. PD-L1 Status and Outcome: Gastric Cancer
PD-L1 is a negative prognostic factor for overall survival in gastric cancer
PD-L1 expression
1.0
Negative
Positive
Negative-censored
0.8
Positive-censored
PD-L1 Negative (n=65)
0.6
Cumulative Survival
0.4
PD-L1 Positive
(n=67)
0.2
PD-1, programmed death-1; PD-L1, programmed death ligand-1.
0.0 24 48 72 96
120
144
168
Time after surgery (months)
Zhang L et al. Int J Clin Exp Pathol. 2015;8(9):

28. Implications Genomic Analysis Gastric cancer is not one disease.
Subtypes of gastric cancer exist.
Observed differences in response to therapy and prognosis may be explained.
Different molecular drivers
Different therapeutic targets