Preoperative Screening of Colorectal Cancers Is As Accurate As Postoperative Screening for Detection of Lynch Syndrome.

Lynch syndrome (LS) is the most common inherited colorectal cancer (CRC) syndrome with lifetime CRC risks of up to 70%.1 Conventionally, CRC specimens are screened for LS postoperatively but preoperative diagnosis of LS could impact decisions, such as the extent of resection and the need for additional risk-reducing surgeries for uterine and ovarian cancers. Few studies have addressed this issue2-5 and surveys indicate that most gastroenterologists are unsure that LS can be screened for preoperatively.6 We compared the yield of preoperative versus postoperative screening of LS by immunohistochemistry (IHC) and microsatellite instability (MSI) in unselected patients with newly diagnosed CRC who underwent testing under real-life laboratory conditions to mimic clinical practice.