Report in English with a Dutch summary (KCE reports 45A)

KCE reports vol.45 Screening for Colorectal Cancer 43
Risk level
Average
Moderate
High
Table 9: ASGE stratification on CRC risk - 2004
Lifetime risk
of CRC
Age > 50 y 5% - 6%
Chronic colitis due to ulcerative colitis or Crohns disease 20%
Familial risk: 1st degree relative with CRC 10% - 20%
Familial polyposis 100%
HNPCC 80%
Familial aggregation, a primary theme in genetic epidemiology, can be estimated
from family studies based on an index person. The excess risk due to the
presence of affected family members can be classified according to whether
disease in the relatives is considered a risk factor for the index person (type I
relative risk) or whether the disease status of the index person is considered a
risk factor for the relatives (type II relative risk). Type I relative risks are useful
in clinical counselling settings when an individual wants to know his/her disease
risk given his or her family history. Type II relative risks can be used to quantify
the risk of disease to relatives of an affected individual and then identify subjects
eligible for screening. A meta-analysis of published colorectal cancer studies
reporting a measure of familial association 114 with application of multilevel linear
regression to model age-specific relative risks showed that the pooled type I
relative risk of colorectal cancer given any affected first-degree relative (based
on 20 studies) was 2,26 (95% CI: 1,86 - 2,73) and decreased with the age of the
individual. The pooled type II estimate (based on seven studies) was 2,81 (95%
CI: 2,05 - 3,85).
Finally, Butterworth et al. from the Cambridge Public Health Genetics Unit
recently published a systematic review 148 of the literature on familial risks of
colorectal cancer. Fifty-nine studies were identified including 47 that estimated
the relative risk of developing colorectal cancer given at least one affected firstdegree
relative. Pooled risk estimates are summarized in Table 10.
Table 10: Pooled estimations of RR and Lifetime Risk of developing
CRC - Butterworth et al. - 2006
Family History Relative Risk for CRC Lifetime risk at 50 years
One first-degree relative with
colorectal cancer
More than one first-degree
relative with colorectal cancer
3.3.5 Economic evaluations
2,24 (95% CI: 2,06 - 2,43) 3,4% (95% CI: 2,8 to 4,0)
3,97 (95% CI: 2,60 - 6,06) 6,9% (95% CI: 4,5 to 10,4)
Recently, a preliminary economic analysis of family history assessment to detect
increased risk for colorectal cancer was published by Ramsey et al 111. The
authors developed a decision model to compare costs and outcomes for two
scenarios: (a) standard population screening starting at age 50; (b) family history
assessment at age 40, followed by screening colonoscopy at age 40 for those
with a suggestive family history of colorectal cancer. The analysis was conducted