Mutations in the mismatch repair genes cause hereditary nonpolyposis colorectal cancer syndrome and convey high lifetime cancer risks for colorectal and endometrial cancer.
Currently, cancer risks for individuals with hereditary nonpolyposis colorectal cancer are based on data from clinically ascertained families.
Dr Hampel and colleagues re-examined the penetrance in hereditary nonpolyposis colorectal cancer using a comprehensive dataset from a geographically defined region.
The researchers included 70 hereditary nonpolyposis colorectal cancer families ascertained by traditional high-risk criteria and by molecular screening.
A combined dataset was used comprising 88 probands and 373 mutation-positive family members.
|The lifetime risk for colorectal cancer was 69% for men and 52% for women|
The team modified survival analysis techniques.
The team found that in mutation-positive relatives, the median age at diagnosis of colorectal cancer was 61 years.
The lifetime risk for colorectal cancer was 69% for men and 52% for women.
Considering only probands, the team found that the median age at diagnosis of colorectal cancer was 44 years.
The researchers observed that the median age of onset of EC was 62 years with a lifetime cancer risk of 54%.
Dr Hampel's team concludes, “A markedly later age of onset for colorectal cancer at 61 years than the previously reported 44 years is suggested.”
“The later onset results mainly from a more rigorous method of analysis in which all gene-positive individuals, both affected and unaffected with cancer, are considered.”
“Lifetime cancer risks may be lower for colorectal cancer and endometrial cancer than presently assumed.”
“If confirmed, these data suggest a need to alter counseling practices, and to consider hereditary nonpolyposis colorectal cancer in older individuals than before.”