High risk of rectal cancer and of metachronous colorectal cancer in probands of families fulfilling the Amsterdam criteria.

Objective: To investigate the risk of metachronous colorectal cancer (CRC), its impact on survival, and the risk of rectal cancer in a cohort of probands meeting the Amsterdam criteria.

Background: Several determinants of decision-making for the management of CRC in patients with a putative diagnosis of Lynch syndrome are scarcely defined, and many of them undergo segmental bowel resection instead of the advised total colectomy.

Methods: A retrospective cohort study was conducted on 65 probands of the Amsterdam-positive families who had surgery for primary CRC and at least 5-year surveillance thereafter. The rates of metachronous CRC and of rectal cancer were evaluated, together with their association with preoperatively available clinical predictors. Differences in overall survival between patients with and without metachronous CRC were evaluated using a time-dependent Cox model.

Results: Seventeen patients (26.2%) had metachronous CRC. No clinical feature was associated with an increased risk of its development. The risk of death in patients with metachronous CRC was 6-fold increased. Neither a 2-year interval endoscopic surveillance after surgery, nor total colectomy was associated with a significant reduction in metachronous CRC. Eighteen patients (23.7%) had rectal cancer at first presentation, 5 patients of the remainder (10.6%) developed rectal cancer after primary colon resection. Two patients undergoing total colectomy developed a metachronous rectal cancer (18.2%). A first-degree family history of rectal cancer was associated with an increased risk of rectal cancer.

Conclusions: Probands of families fulfilling the Amsterdam criteria carry a high risk of rectal cancer and of metachronous CRC. Total proctocolectomy, or total colectomy and a 1-year interval of proctoscopic surveillance should be advised when a high risk of rectal cancer can be predicted.