A predictive model of metachronous colorectal cancer occurrence in Lynch syndrome

A total of 1,604 CRC patients (M/F=1.02, 16.5% <40 yrs old) were considered (600 in group A, 117 B, 530 C and 357 D). During the follow-up, 181 developed metachronous CRC (11 %) and 354 (22%) an extracolonic cancer. The risks of metachronous CRC at 10 years were 21%, 16%, 16%, and 14% for group A, B, C and D, respectively. The predictive variables in the final model comprised for each group were: A) MLHI mutation, the presence of colorectal adenomas and then occurrence of extracolonic cancers, B) occurrence of extracolonic cancers, C) high tumor grade and presence of colorectal adenomas. No significant predictors were identified for group D. AUC values, as a measure of discrimination of the various models, were 0.72, 0.78 and 0.76 for group A, B and C, respectively. Conclusions Metachronous CRC is a long-term moderate risk in LS patients. This suggests to recommend a prophylactic colectomy only to selected patients with well defined characteristics.