title: The benefit of microsatellite instability is attenuated by chemotherapy in stage II and stage III gastric cancer: Results from a large cohort with subgroup analyses.
abstract: We previously reported that the prognosis of microsatellite instability high (MSI-H) gastric cancer is similar to that of MSI-low/microsatellite stable (MSI-L/MSS) gastric cancer. The reason for this seemed to be related to the effects of chemotherapy. To verify this hypothesis, we expanded the study population and reanalyzed the prognosis of MSI-H gastric cancer. Data from 1,276 patients with Stage II and III gastric cancer who underwent gastrectomy with curative intent between January 2005 and June 2010 were reviewed. The prognosis of MSI-H tumors in comparison with MSI-L/MSS tumors was analyzed, according to the administration of chemotherapy and other clinicopathologic features. A total of 361 (28.3%) patients did not receive chemotherapy (MSI-H = 47 and MSI-L/MSS = 314), whereas 915 (71.7%) patients did receive chemotherapy (MSI-H = 58 and MSI-L/MSS = 857). The hazard ratio of MSI-H versus MSI-L/MSS was 0.49 (95% confidence interval: 0.26-0.94, p = 0.031) when chemotherapy was not received and 1.16 (95% confidence interval: 0.78-1.71, p = 0.466) when chemotherapy was received. In subgroup analyses, the prognosis of MSI-H was better in Stage III, women, with lymph node metastasis, and undifferentiated histology subgroups when chemotherapy was not received. However, in patients treated with chemotherapy, prognosis was worse for MSI-H tumors in Stage III, undifferentiated histology, and diffuse type subgroups of gastric cancer. In conclusion, MSI-H tumors were associated with a good prognosis in Stage II and III gastric cancer when patients were treated by surgery alone, and the benefits of MSI-H status were attenuated by chemotherapy.
authors.affiliation: Department of Surgery, Yonsei University College of Medicine, Seoul, Republic of Korea.
authors.forename: Soo Young
authors.initials: SY
authors.lastname: Kim
authors.affiliation: Department of Surgery, Yonsei University College of Medicine, Seoul, Republic of Korea.
authors.forename: Yoon Young
authors.initials: YY
authors.lastname: Choi
authors.affiliation: Department of Surgery, Yonsei University College of Medicine, Seoul, Republic of Korea.
authors.forename: Ji Yeong
authors.initials: JY
authors.lastname: An
authors.affiliation: Department of Surgery, Yonsei University College of Medicine, Seoul, Republic of Korea.
authors.forename: Hyun Beak
authors.initials: HB
authors.lastname: Shin
authors.affiliation: Brain Korea 21 Plus Project for Medical Science, Yonsei University Health System, Yonsei University College of Medicine, Seoul, Republic of Korea.
authors.forename: Ara
authors.initials: A
authors.lastname: Jo
authors.affiliation: Brain Korea 21 Plus Project for Medical Science, Yonsei University Health System, Yonsei University College of Medicine, Seoul, Republic of Korea.
authors.forename: Hyeji
authors.initials: H
authors.lastname: Choi
authors.affiliation: Department of Surgery, Yonsei University College of Medicine, Seoul, Republic of Korea.
authors.forename: Sang Hyuk
authors.initials: SH
authors.lastname: Seo
authors.affiliation: Department of Surgery, Yonsei University College of Medicine, Seoul, Republic of Korea.
authors.forename: Hui-Jae
authors.initials: HJ
authors.lastname: Bang
authors.affiliation: Department of Surgery, Yonsei University College of Medicine, Seoul, Republic of Korea.
authors.forename: Jae-Ho
authors.initials: JH
authors.lastname: Cheong
authors.affiliation: Department of Surgery, Yonsei University College of Medicine, Seoul, Republic of Korea.
authors.forename: Woo Jin
authors.initials: WJ
authors.lastname: Hyung
authors.affiliation: Department of Surgery, Yonsei University College of Medicine, Seoul, Republic of Korea.|Brain Korea 21 Plus Project for Medical Science, Yonsei University Health System, Yonsei University College of Medicine, Seoul, Republic of Korea.
authors.forename: Sung Hoon
authors.initials: SH
authors.lastname: Noh
mesh_terms: D000328:Adult; D000368:Aged; D004358:Drug Therapy; D005260:Female; D005472:Fluorouracil / Q000008:administration & dosage; D006801:Humans; D008207:Lymphatic Metastasis / Q000235:genetics / Q000473:pathology; D008297:Male; D053842:Microsatellite Instability; D008875:Middle Aged; D009367:Neoplasm Staging; D011379:Prognosis; D013274:Stomach Neoplasms / Q000188:drug therapy* / Q000235:genetics* / Q000473:pathology
chemical_list: D005472:Fluorouracil
keywords: chemotherapy; gastric cancer; microsatellite instability; prognosis