Colorectal cancer risk perception on the basis of genetic test results in individuals at risk for Lynch syndrome.
OBJECTIVE
Lynch syndrome is associated with inherited germline mutations in mismatch repair (MMR) genes. Genetic testing in high-risk individuals may yield indeterminate results if no mutation is found or if a mutation of unclear pathogenic significance is observed. There are limited data regarding how well patients with Lynch syndrome understand the clinical implications of genetic test results. This study examines colorectal cancer (CRC) risk perception in individuals tested for MMR mutations and identifies the factors associated with an appropriate interpretation of their cancer risk.


METHODS
A total of 159 individuals who met the Revised Bethesda Guidelines and had previously undergone genetic testing completed a questionnaire eliciting demographic data, cancer history, genetic test results, and an estimate of their CRC risk. Associations between clinical factors, genetic test results, and CRC risk perception were explored using multivariable analyses.


RESULTS
Of the 100 individuals with a pathogenic mutation (true positive), 90 (90%) correctly estimated their CRC risk as "high" or "very high" compared with other individuals their age. However, only 23 (62%) of 37 individuals with an indeterminate genetic test result correctly estimated their risk. Individuals with a history of Lynch syndrome-associated cancer (odds ratio [OR], 0.1; 95% CI, 0.1 to 0.6) or indeterminate genetic test results (OR, 0.2; 95% CI, 0.1 to 0.6) were significantly less likely to estimate their CRC risk as increased.


CONCLUSIONS
Patients at risk for Lynch syndrome with an indeterminate genetic test result may be falsely reassured. It is important that health care providers continue to discuss the implications of uninformative results on lifetime cancer risk.
Grover
Shilpa
S
Division of Gastroenterology, Department of Medicine, Brigham and Women's Hospital, Boston, MA, USA.
Stoffel
Elena M
EM
Mercado
Rowena C
RC
Ford
Beth M
BM
Kohlman
Wendy K
WK
Shannon
Kristen M
KM
Conrad
Peggy G
PG
Blanco
Amie M
AM
Terdiman
Jonathan P
JP
Gruber
Stephen B
SB
Chung
Daniel C
DC
Syngal
Sapna
S
D000293:Adolescent; D000328:Adult; D000368:Aged; D015179:Colorectal Neoplasms / Q000209:etiology*; D003123:Colorectal Neoplasms, Hereditary Nonpolyposis / Q000235:genetics*; D003430:Cross-Sectional Studies; D053843:DNA Mismatch Repair; D005260:Female; D005817:Genetic Counseling; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D012307:Risk Factors