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.