Trial Information

Stomach and Oesophageal Cancer Study (SOCS)

OBJECTIVES:

- To set up a population-based gastric and esophageal cancer cohort with comprehensive
epidemiological, clinical, and pathological data in order to identify novel genetic and
environmental risk factors for these cancers using an association study design.

- To establish a blood-based epidemiological resource with parallel tumor samples on a
population-based series of gastric and esophageal cancer cases.

- Compare any differences in genetic susceptibility genes according to the site of
esophago-gastric cancer (e.g., distal gastric, proximal gastric, or junctional and
esophageal tumors) and the histopathological sub-type.

- Test existing molecular hypotheses and determine whether common genetic variants in
candidate genes predispose to gastric and esophageal cancer by comparing the frequency
of variants in cancer patients with that in controls.

- Generate new hypotheses of genetic and certain environmental determinants, explore the
potential impact on cancer disease risk of a range of environmental factors that can be
measured in plasma (e.g., antibodies to various infective agents, markers of systemic
inflammation, markers of oxidation), and examine gene-environment interactions.

- Refine our understanding of risk factors that are identified (e.g.,chronic Helicobacter
pylori infection and smoking) and examine how these interact with genetic determinants
of disease.

- Define the proportion of gastric cancer incidence attributable to mutations in known
predisposing genes, such as E-cadherin.

- Obtain data on molecular profiles of tumors (mostly paraffin-embedded, rarely frozen)
using dense array technologies, therefore enabling studies of the interaction between
germline polymorphisms and tumor somatic genotype upon tumor behavior, response to
treatment, and patient outcome.

OUTLINE: This is a multicenter study.

Patients and healthy controls complete an epidemiological questionnaire, provide a blood
sample for plasma and genetic analyses, and may also provide a saliva sample. Tumor samples
(in the form of paraffin block material or, in rare cases, frozen) may also be obtained from
the hospital where the patient underwent surgery.

White blood cells are assayed for DNA/RNA isolation to look at genetic variants. DNA is
extracted from saliva to look at genetic variants. Plasma/serum samples are analyzed to look
at proteins and serological markers. Tumor samples are used to review the histology type.
Nucleic acids are extracted from tumor sample sections; retrieval of a small (0.6 mm) core
from each section is used to construct a tissue microarray which are be analyzed by
immunohistochemistry and FISH.

Peer Reviewed and Funded or Endorsed by Cancer Research UK.

PROJECTED ACCRUAL: A total of 1,000 patients per cancer (gastric and esophageal) and 2,000
controls will be accrued for this study.