WCGI 2018 - Genetic Testing for Familial and Hereditary Colorectal Cancer


  • Carolina Rojido
  • Univadis
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Takeaway

  • Microsatellite instability (MSI) screening should be done for all tumors. Many are MSI High (different outcomes and treatment response).

Why it matters

Genetic risk assessment is useful for:

  • Pre-surgical decision making.
  • Predictive and prognostic treatment implications.
  • Cancer prevention and surveillance for survivors and their families.

Key points

  • Hereditary susceptibility to colorectal cancer (CRC): 65 – 85% sporadic, 15 – 25% are familial, 3% are Lynch Syndrome (LS).
  • An assessment of 15,000 tumor samples showed MSI High is relatively frequent in CRC (14%) and gastric (6%).
  • MSI High is predictive of LS (45% of LS are MSI High).

LS

  • No improvement with 5 Fluorouracil (NCCN guidelines).
  • All MSI-H cancer should be tested for Lynch Syndrome.

Multi gene panel testing is available and appropriate in some patients:

  • Simultaneous analysis of a set of genes.
  • Testing can be difficult, using these panels helps.
  • May or may not be associated with a specific cancer phenotype.
  • Variants and incidental findings are a real limitation! The risks of using this panels are incidental findings and questions about preventive resections (hysterectomy, colon).
  • Inclusion of genes with limited clinical validity and clinical utility.