DNA Mismatch Repair-Deficient Colorectal Carcinoma: Referral Rate for Genetic Cancer Risk Assessment in a Brazilian...

Area of Science:

• Oncology
• Genetics
• Cancer Research

Background:

• Approximately 15% of colorectal cancers (CRCs) exhibit DNA mismatch repair deficiency (dMMR).
• dMMR is observed in both sporadic and hereditary CRC cases.
• Limited research exists on dMMR CRC within the Brazilian population.

Purpose of the Study:

• To analyze referral rates for Genetic Cancer Risk Assessment in Brazilian dMMR CRC patients.
• To provide clinical and molecular characterization of dMMR CRC tumors in this population.

Main Methods:

• Retrospective, longitudinal, unicenter study.
• Included patients with dMMR CRC identified via immunohistochemistry (IHC) from January 2015 to July 2017.
• Analysis of MMR IHC testing results, patient demographics, tumor characteristics, and genetic counseling/testing referrals.

Main Results:

• 7.8% (78/998) of CRC tumors tested were dMMR.
• The average age of diagnosis was 56.8 years, with a slight female predominance (52.6%).
• Only 55.1% of dMMR CRC patients were referred for genetic counseling, and 43.6% ultimately underwent genetic testing.

Conclusions:

• Genetic referral rates for dMMR CRC in this Brazilian cohort were lower than anticipated.
• A significant number of dMMR CRC patients did not receive genetic counseling, even within a cancer center.
• Few patients who attended genetic counseling proceeded to genetic testing, indicating potential barriers in the referral and testing pathway.