We examined the clinicopathological features of 4 patients with
Lynch syndrome (including those with strongly suspected
Lynch syndrome) who had undergone
chemotherapy as part of the treatment for
colon cancer. The study population included 3 men and 1 woman. The median age at diagnosis was 72 years (range, 24-40 years). Two patients relapsed and 2 patients had Stage IV
cancer. All the patients had primary right-sided
colon cancer. On histopathological examination, well differentiated
adenocarcinoma, moderately differentiated
adenocarcinoma, and poorly differentiated
adenocarcinoma were observed in 1, 2, and 1 patients, respectively. Components of
mucinous adenocarcinoma or poorly differentiated
adenocarcinoma were observed in all patients.
Microsatellite instability (MSI) testing revealed high MSI (MSI-H) in all patients. Immunostaining results indicated loss of expression of the MSH2/MSH6
proteins at the
tumor site in all patients. With regard to
chemotherapy, a 5-fluorouracil-based regimen was selected as the first-line of
therapy. Although 1 patient experienced long-term survival (alive at 48 months after surgery), the other 3 patients died of
cancer within 9 months. The median overall survival was 8.5 months. Active assessment and accumulation of such cases is essential for the establishment of appropriate and effective treatments for
colon cancer in patients with
Lynch syndrome.