Nearly one-fifth of patients who develop colorectal cancer at a young age (40 and younger) have a family history consistent with a familial colorectal cancer syndrome known as hereditary nonpolyposis colorectal cancer (HNPCC), according to researchers at Memorial Sloan-Kettering Cancer Center. The study, published in the January 1999 issue of Diseases of the Colon and Rectum, looked at 230 patients £ 40 years of age who were diagnosed with colorectal cancer and found that nearly 20% of them had the HNPCC syndrome.
Criteria for Diagnosis
Hereditary nonpolyposis colorectal cancer is a dominantly inherited disorder, accounting for about 5% of all colorectal cancer cases. It is generally a fast-growing cancer that affects people primarily in their 40s. People who carry the genetic mutation for HNPCC have an 80% to 85% lifetime risk of developing colorectal cancer and are at increased risk of developing endometrial, ovarian, stomach, kidney, and other cancers. The criteria for a clinical diagnosis of HNPCC include: three first-degree relatives with colorectal cancer, spanning two generations, one of whom is less than 50 years of age at the time of diagnosis.
This would exclude individuals with another type of inherited colorectal cancer called familial adenomatous polyposis, a condition in which people develop hundreds of colon polyps at a very young age.
Early, Often Aggressive, Intervention Often Warranted
Individuals who develop colorectal cancer at a young age require special surveillance to protect them from developing other types of cancers, said Dr. Jose Guillem, associate attending surgeon at Memorial Sloan-Kettering Cancer Center and lead author of the study. By identifying and tracking individuals with HNPCC, we can intervene at an early stage and make appropriate, and where warranted, aggressive treatment decisions to prevent the development of additional colorectal and other cancers. In addition, family members of individuals who develop colorectal cancer at an early age should now be monitored more closely, said Dr. Guillem.
The study also found that those with HNPCC had a 13 times higher rate of developing additional colorectal tumors, compared with those in the non-HNPCC group (27% vs 2%). That finding supports the recommendation for performing more extensive surgery to reduce the risk of developing a subsequent colorectal cancer in these patients.
While current guidelines recommend screening for colorectal cancer beginning at age 50 years for people at average risk or at age 40 years for those with a family history of the disease, individuals with HNPCC are advised to seek genetic counseling and screening with a colonoscopy every 1 to 3 years beginning at age 20 years.
It is becoming increasingly important for people to know their family history and pay special attention to cancers that were detected at an early age, said Dr. Guillem. Those individuals and their first-degree family members need to be screened more frequently and earlier than the general population for colorectal and other cancers.
Memorial Sloan-Kettering maintains a registry of patients and their families who have early-onset colorectal cancer or a history consistent with HNPCC or familial adenomatous polyposis, as part of an international collaborative effort to identify, follow, study, and properly care for these individuals.