Table 1.

Theoretical Outline of Molecular Screening for HNPCC in the United States:Annual Outcome

	Population
No. of patients newly diagnosed with colorectal cancer	140,000
No. of tumors tested for MSI	140,000
No. of patients with MSI of tumor (12%)	16,800
Search for mutations in MLH1, MSH2, MSH6	16,800
No. of patients with germline mutation (3%)= new HNPCC probands	4,200
No. of relatives at risk tested (10 per proband; test for proband’s mutation only)	42,000
No. of relatives with germline mutation (40%)	16,800
Total no. of new cases of HNPCC (4,200 + 16,800)	21,000