Results of the examinations for microsatellite instability in the tumours and screening for germline mutations in the hMSH2 and hMLH1 genes in the index patients of the four different groups
| Group 1 | Group 2 | Group 3 | Group 4 | ||
|---|---|---|---|---|---|
| Number of unrelated patients | 57 | 12 | 45 | 46 | |
| Mean age at diagnosis of the first colorectal cancer (years) | 44 (11.8) | 37 (10.8) | 42 (8.3) | 39 (10.2) | |
| Number of tumour tissues examined for MSI | 493-150 | 83-150 | 45 | 46 | |
| MSI+ | 35 (71.4%) | 4 (50%) | 26 (57.8%) | 16 (34.8%) | |
| MSI− | 12 | 1 | 18 | 26 | |
| MSI? | 2 | 3 | 1 | 4 | |
| Examined for germline mutations | 57 | 12 | 17 | 10 | |
| Total number of identified mutations | 15 (26%) | 2 (17%) | 5 | 3 | |
| Proportion of identified mutations in patients with MSI+ tumours | 13/353-151 | 2/4 | 5/17 | 3/10 | |
| (37%) | (50%) | (29%) | (30%) | ||
Group 1, Amsterdam criteria; group 2, looser criteria including extracolonic cancers; group 3, some familial clustering of tumours; group 4, no family history (age at diagnosis <50 years).
↵3-150 In eight patients of group 1 and four patients of group 2 no tumour tissue was available.
↵3-151 In two patients with identified germline mutations no tumour tissue was available.