Metachronous colorectal cancer risk in Lynch syndrome patients-should the endoscopic surveillance be more intensive? 
Regular follow-up for patients with Lynch syndrome (LS) is vital due to the increased risk of colorectal (50-80%), endometrial (40-60%), and other cancers.  However, there is an ongoing debate concerning the best interval between colonoscopies.  Currently, no specific endoscopic follow-up has been decided for LS patients who already have an index colorectal cancer (CRC).  The aim of this study was to evaluate the risk of metachronous cancers (MC) after primary CRC in a LS population and to determinate if endoscopic surveillance should be more intensive.  A prospective cohort of patients with a confirmed diagnosis of hereditary CRC since 2009 was included.  Patients with LS and a primary CRC were the cohort of choice.  One hundred twenty-one patients were included with a median age of 44 years(16-70).  At least one MC occurred in 39 patients (32.2%), with a median interval of 67 months (6-300) from index cancer.  Fifteen (38.5%) developed two or more MCs during follow-up, with a median number of two (2-6) tumors occurring.  Metachronous CRC were diagnosed after a median interval of 24 (6-57) months since last colonoscopy and were more commonly seen in MSH2 mutation carriers (58 vs. 35%, p = 0.001).  After a median follow-up of 52.9 (3-72) months, no cancer-related deaths were recorded.  Patients with LS have an increased risk of MC, especially CRCs.  With a median time period of 24 months between colonoscopy and metachronous CRC, the interval between surveillance colonoscopies following primary CRC should not exceed 18 months, especially in patients with MSH2 mutation.