A Scoring System for the Strength of a Family History of Colorectal Cancer

Abstract

Family history of colorectal cancer is associated with an increased risk for the disease, although there are many combinations of family history that are hard to correlate with risk status. A scoring system for family history of colorectal cancer was designed to make risk more readily quantifiable. A colonoscopy database was used to test the following points system: each first-degree relative with colorectal cancer = 3 points; each second-degree relative with colorectal cancer = 1 point. Families with one or more first-degree relative affected under 50 years of age = an extra 3 points. Families with one or more second-degree relative affected under 50 years of age = an extra 1 point. Families with multiple relatives on the same side of the family = an extra 3 points (first-degree relatives), 1 point (second-degree relatives), or 2 points (first-degree and second-degree relatives). Points were added and categories defined as follows: low risk, 1 to 4 points; medium risk, 5 to 7 points; high risk, 8 to 10 points; very high risk, >10 points. A control group of average-risk patients having screening colonoscopy was used. Categories were compared in number of adenomas, hyperplastic polyps, and cancers. The records of 992 patients were used to test the system. Mean adenomas per patient per group were 0.4 for controls, 1.0 for low risk, 1.0 for medium risk, 1.7 for high risk, and 1.7 for very high risk. Cancers per group were 2 of 196 for controls, 8 of 513 for low risk, 3 of 171 for medium risk, 3 of 84 for high risk, and 1 of 28 for very high risk. The score categories were combined to produce revised risk levels of low (score 1 to 7) and high (>7). Average adenomas per patient in the revised categories were 0.4 (control), 1.0 (low risk), and 1.7 (high risk). The odds ratio of having one to two adenomas was 1.73 (1.19-2.50, 95% confidence limits) in the low-risk group and 2.39 (1.41-4.01) in the high-risk group. Odds ratios for having three or more adenomas were 5.70 (2.44-13.32) in the low-risk group and 10.35 (3.97-26.97) in the high-risk group. In the two-category system proposed here of quantifying familial risk of colorectal cancer, patients having less than 8 points were at low risk and those with 8 or more were at high risk. Surveillance and chemoprevention protocols can be designed through use of these risk categories. A scoring system for family history of colorectal cancer can make risk assessment easier and facilitate both collaborative studies and patient triage into appropriate screening programs.