eP613 - Prevalence of Mismatch Repair Deficiency in Elective Colorectal Cancer Surgery in a Tertiary South American Hospital

Monday, June 3, 2024

11:00 AM – 11:05 AM ET, USA

Location: Baltimore Convention Center, Room 318-320

ePoster Presenter(s)

Gustavo J. Montesinos

Colorectal Surgery
Hospital Regional de Rancagua
Requínoa, Libertador General Bernardo O'Higgins, Chile

All of the relevant financial relationships listed below have been mitigated.
This individual has no financial relationships with ineligible companies.

Author(s)

VF

Valentina P. Fernández, n/a

Intern of Medicine
Universidad de O'Higgins
Santiago, Region Metropolitana, Chile

Disclosure information not submitted.
JV

Joaquin A. Vega, n/a

Medical Student
Universidad de O´Higgins
Rancagua, Libertador General Bernardo O'Higgins, Chile

Disclosure information not submitted.
CS

Catalina Saavedra Gonzalez

Disclosure information not submitted.
PL

Paulina A. Leyton, Hospital Regional Libertador Bernardo OHiggins

Intern of Medicine
Universidd de OHiggins
Rancagua, Libertador General Bernardo O'Higgins, Chile

Disclosure information not submitted.
PC

Paz Cardenas, Hospital libertador Bernardo O'Higgins

Intern of medicine
Universidad de O'Higgins
Nacimiento, Bio-Bio, Chile

Disclosure information not submitted.
Jorge Escarate

Colorrectal surgeon
Hospital regional de rancagua
Universidad de O'Higgins
Rancagua, Libertador General Bernardo O'Higgins, Chile

All of the relevant financial relationships listed below have been mitigated.
This individual has no financial relationships with ineligible companies.
GP

Guillermo H. Perez, -

Colorectal Surgery
HRLBO
Rancagua, Chile, Libertador General Bernardo O'Higgins, Chile

Disclosure information not submitted.
RA

Renatto Anfossi, PharmD

Head of Research Department
Hospital Regional Libertador Bernardo O'Higgins
Rancagua, Libertador General Bernardo O'Higgins, Chile

Disclosure information not submitted.

Purpose/Background: Colorectal cancer (CRC) is the second most common neoplasm in the country in both men and women. Most of these cancers are sporadic, but about 10% have an hereditary component. Some of them are due to mutations in the expression of DNA mismatch repair proteins (MMR). Lack of expression of MLH1, MSH2, PMS2 and MSH6 is strongly associated with the presence on Lynch Syndrome. The diagnostic confirmation is by detection of germline mutations.
The objective of this study is to identify patients at the Hospital Regional del Libertador Bernardo O'Higgins (HRLBO) with a suspected Lynch syndrome (LS) using surgical-biopsy immunohistochemistry approach to know its local prevalence between 2018 and 2022.Methods/Interventions: Observational retrospective study of patients electively operated for CRC between 2018 and 2022 at HRLBO. The lack-of-expression of any of the proteins was considered as deficient MMR (dMMR) and the presence of all four proteins is considered as sufficient MMR (pMMR). Graphpad-Prism-8 software was used for statistical analysis.Results/Outcomes: Of a total of 217 patients 28 of them (12.9%) were dMMR. The most frequent combination of mutations was MLH1-PMS2 with 9 patients; MSH6 with 7 and MSH2-MSH6 with 4. Patients with dMMR presented CRC most frequently in the right colon, while patients in the pMMR group were located mainly it in the rectum. Lack of expression of MSH6 and MLH1-PMS2 were found to be more represented in the rectum and right colon, respectively.Conclusion/

Discussion: Immunohistochemistry would allow us to relate the most frequent mutations with the location of the cancer; however, genetic studies are needed to confirm the diagnosis el LS. This will allow screening for suspected LS with identification of specific mutations and therefore genetic and family counseling.