During the last 15 years, several single-gene mendelian disorders have been discovered that might account for some of the familial aggregation detected in large population studies of colorectal cancer.
Mutations in DNA mismatch repair genes cause hereditary nonpolyposis colorectal cancer-Lynch syndrome.
|The relative risk for colorectal cancer was greatest in siblings|
|Clinical Gastroenterology and Hepatology|
It is the most common of the recognized colorectal cancer-predisposition syndromes, in which one major feature is a young age for cancer onset.
However, for young-onset microsatellite stable colorectal cancer, the familial risk for colorectal cancer is unknown.
Dr Lisa Boardman and colleagues evaluated patients with colorectal cancer who were under 50 years old through the Minnesota Cancer Surveillance System, and Mayo Clinic in Minnesota, USA.
The research team excluded patients with colorectal cancers where the DNA mismatch repair function was found to be deficient.
This was evidenced by high level microsatellite instability and/or loss of expression of mismatch repair gene product by immunostaining.
The team identified a total of 278 probands.
Data on 1862 relatives were collected, of whom 68 were found to have had colorectal cancer, and an additional 165 had primary cancers of other types.
The researchers compared patient data from Surveillance Epidemiology and the End Results program.
The research team found that relatives of young-onset colorectal cancer probands had increased risks for colorectal cancer.
This relative risk was increased among first-degree relatives, and was greater for siblings than parents.
Dr Boardman's team commented, "We studied 278 probands with young-onset microsatellite stable colorectal cancer."
"We determined that the relative risk for colorectal cancer was greatest in siblings, which is consistent with an autosomal recessive inheritance pattern."