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Ann Surg Oncol. 2017 May;24(5):1289-1294. doi: 10.1245/s10434-016-5682-5. Epub 2016 Nov 16.

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).

Author information

1
Department of Oncology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
2
Department of Preventive Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
3
Department of Colorectal Surgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
4
Department of Pathology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
5
Department of Oncology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea. twkimmd@amc.seoul.kr.

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.

PMID:
27853901
DOI:
10.1245/s10434-016-5682-5
[Indexed for MEDLINE]

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