title: Microsatellite Instability was not Associated with Survival in Stage III Colon Cancer Treated with Adjuvant Chemotherapy of Oxaliplatin and Infusional 5-Fluorouracil and Leucovorin (FOLFOX).
abstract: BACKGROUND
  The impact of microsatellite instability (MSI) on survival in stage III colon cancer treated with adjuvant 5-fluorouracil-oxaliplatin combination (FOLFOX) chemotherapy is not clear. We evaluated the association between MSI and survival in this population.
  
  
  METHODS
  We analyzed 598 patients with curatively resected stage III colon cancer treated with adjuvant FOLFOX chemotherapy. We determined MSI status using polymerase chain reaction amplification; tumors were classified as high MSI (MSI-H, ≥2 unstable markers), low MSI (MSI-L, 1 unstable marker), or microsatellite stable (MSS, no unstable marker).
  
  
  RESULTS
  Of 598 patients, 8.4% showed MSI-H. Tumors classified as MSI-H were more commonly located in the ascending colon (54.0 vs. 27.7%, p < 0.0001) and had poorly differentiated features (32.0 vs. 8.0%, p < 0.0001). After the median follow-up of 52.8 months, 5-year disease-free (DFS) and overall survival (OS) rates were 77.0 and 85.9%, respectively. In univariate analysis, pathologic T4 (pT4) and pathologic N2 (pN2) was associated with reduced DFS (p < 0.0001 and p < 0.0001, respectively) and OS (p = 0.002 and p = 0.001, respectively), whereas MSI status did not affect either DFS (p = 0.114) or OS (p = 0.525). In patients with pN2 tumors; however, MSI-H was associated with better survival compared with MSS/MSI-L; DFS and OS in patients with MSI-H/pN2 were comparable to those in patients with pN1 tumors.
  
  
  CONCLUSIONS
  In patients with stage III colon cancer treated with adjuvant FOLFOX, pT4 and pN2 was associated with reduced survival, but MSI status alone did not affect survival.
authors.affiliation: Department of Oncology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Jeong Eun
authors.initials: JE
authors.lastname: Kim
authors.affiliation: Department of Oncology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Yong Sang
authors.initials: YS
authors.lastname: Hong
authors.affiliation: Department of Preventive Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Hwa Jung
authors.initials: HJ
authors.lastname: Kim
authors.affiliation: Department of Oncology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Kyu-Pyo
authors.initials: KP
authors.lastname: Kim
authors.affiliation: Department of Oncology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Sun Young
authors.initials: SY
authors.lastname: Kim
authors.affiliation: Department of Colorectal Surgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Seok-Byung
authors.initials: SB
authors.lastname: Lim
authors.affiliation: Department of Colorectal Surgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: In Ja
authors.initials: IJ
authors.lastname: Park
authors.affiliation: Department of Colorectal Surgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Chan Wook
authors.initials: CW
authors.lastname: Kim
authors.affiliation: Department of Colorectal Surgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Yong Sik
authors.initials: YS
authors.lastname: Yoon
authors.affiliation: Department of Colorectal Surgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Chang Sik
authors.initials: CS
authors.lastname: Yu
authors.affiliation: Department of Colorectal Surgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Jin Cheon
authors.initials: JC
authors.lastname: Kim
authors.affiliation: Department of Pathology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Ji Hun
authors.initials: JH
authors.lastname: Kim
authors.affiliation: Department of Oncology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea. twkimmd@amc.seoul.kr.
authors.forename: Tae Won
authors.initials: TW
authors.lastname: Kim
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000008:administration & dosage / Q000627:therapeutic use*; D017024:Chemotherapy, Adjuvant; D044682:Colon, Ascending; D003110:Colonic Neoplasms / Q000235:genetics* / Q000401:mortality / Q000473:pathology / Q000628:therapy*; D018572:Disease-Free Survival; D005260:Female; D005472:Fluorouracil / Q000008:administration & dosage / Q000627:therapeutic use; D006801:Humans; D002955:Leucovorin / Q000008:administration & dosage / Q000627:therapeutic use; D008207:Lymphatic Metastasis; D008297:Male; D053842:Microsatellite Instability; D008875:Middle Aged; D060787:Neoplasm Grading; D009367:Neoplasm Staging; D009944:Organoplatinum Compounds / Q000008:administration & dosage / Q000627:therapeutic use; D000077150:Oxaliplatin; D015996:Survival Rate; D047368:Tumor Burden; D055815:Young Adult
chemical_list: D009944:Organoplatinum Compounds; D000077150:Oxaliplatin; D002955:Leucovorin; D005472:Fluorouracil