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Hereditary aspects of upper GI malignancy. Eamonn Sheridan Consultant in Clinical Genetics. Familial tendancy to malignancy. Tends to be dominant Early onset of disease Rare FAP 1/8000 HNPCC 1/2500 Peutz Jeghers 1/50000 Juvenile polyposis 1/100,000 TOC two families Extra GIT features.
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Hereditary aspects of upper GI malignancy Eamonn Sheridan Consultant in Clinical Genetics
Familial tendancy to malignancy • Tends to be dominant • Early onset of disease • Rare • FAP 1/8000 • HNPCC 1/2500 • Peutz Jeghers 1/50000 • Juvenile polyposis 1/100,000 • TOC two families • Extra GIT features
Familial risks • Expressed as odds ratios • Oesophageal cancer 1.6 • Gastric cancer 2.1- 3.1 • Small bowel tumours 2.6-3.1 • No indication for screening at these levels of risk
Mendelian cancer predisposition syndromes • FAP • HNPCC • Gastric cancer • Peutz Jegher • Juvenile polyposis
FAP • Hundreds of colonic polyps in second and third decades • Extracolonic manifestations • Gastric polyps • Duodenal polyps • Clear excess of ampullary cancers
HNPCC • No biological phenotype • Amsterdam criteria • RR stomach cancer 4.1 median age 54 • RR small bowel 25 median age 53 • RR Hepatobiliary system 4.9 age 66
Peutz Jegher syndrome • Excess of small bowel tumours • Difficult to identify • Intusseception • Obstruction • Torsion
Dominant Gastric cancer • extremely rare • Few families only with multiple affecteds • Mutations in b-catenin gene • Screening unproven
Oesophageal cancer • Minimal familial tendancy • Two large families with TOC • Linked to chromosome 17 • No gene as yet
Conclusions • Low relative risk for most of these tumours • May be significant risks if part of other syndrome • Screening uncertain