This study aimed to determine the risk of developing a second colorectal cancer (CRC) in patients with Lynch syndrome previously treated with surgical resection of a CRC tumor. The main finding was that patients treated with a partial resection were at a higher risk of a second cancer than those treated with a total resection of the colon.

Lynch syndrome, or Hereditary nonpolyposis colorectal cancer (HNPCC), is a genetic disorder that leads to a higher than normal predisposition to developing colorectal cancer (CRC) as well as other types of cancer. Diagnosis of HNPCC can be made clinically using the Amsterdam criteria. Families with Lynch syndrome usually have several generations and more than three members affected by CRC or other HNPCC-related cancers. In recent years, genetic testing for Lynch syndrome has also become available.

This study analyzed data from 296 patients who had been treated for Lynch syndrome-associated CRC between 1950 to 2009. Most patients were diagnosed with HNPCC based on the Amsterdam criteria. 253 of the patients in the study were treated with partial colon resection (partial colectomy) and 43 with total resections of the colon. Follow up involved regular colonoscopies.

Results showed that 25% of patients in the partial colectomy group had developed a second CRC (recurrence). The second cancer occurred, on average, 69 months (almost 6 years) after surgery. Only 8% of the patients with a total colectomy developed a second cancer (rectal cancer). The number of high-risk pre-cancerous lesions was also higher in the partial colectomy group.

Based on these results, in patients with HNPCC, the authors recommend treating CRC with a total colon resection (total colectomy).

It is important to note that the study included patients diagnosed with Lynch syndrome based on the Amsterdam criteria which are not as sensitive as laboratory genetic testing.