RT Journal
A1 Chang EY, Dorsey PB, Frankhouse J, et al
T1 COmbination of microsatellite instability and lymphocytic infiltrate as a prognostic indicator in colon cancer
JF Archives of Surgery
JO Archives of Surgery
YR 2009
FD June 1
VO 144
IS 6
SP 511
OP 515
DO 10.1001/archsurg.2009.40
UL http://dx.doi.org/10.1001/archsurg.2009.40
AB Background 
    Microsatellite instability (MSI) is a genetic aberration associated with less aggressive tumor biology. Some tumors with MSI also have lymphocytic infiltrate (LI), which suggests a heightened immune response against the tumor.Objective 
    To evaluate the combined prognostic significance of MSI and LI in a colon cancer population.Design 
    Colon cancers were prospectively evaluated for MSI by assessing 11 satellite markers and were classified as MSI+ if 2 or more satellite markers displayed instability. Tumors were classified as LI+ if at least 5 lymphocytes were observed per 10 high-power fields.Setting 
    Community hospital system.Patients 
    Individuals undergoing definitive surgery for colon cancer.Main Outcome Measures 
    Overall and disease-free survival were compared according to combined MSI and LI status.Results 
    In 150 patients, tumors were classified as follows: 95 were MSI−/LI−, 9 were MSI−/LI+, 30 were MSI+/LI−, and 16 were MSI+/LI+. Median follow-up was 40.6 months. Five-year disease-free survival was 56.7% for patients with MSI−/LI− tumors and 88.9% for those with MSI+/LI+ tumors (P = .01). Patients with MSI+/LI− and MSI−/LI+ tumors had 5-year survival of 75.4% and 75.0%, respectively.Conclusions 
    Patients with colon cancer and MSI−/LI− tumors have worse disease-free survival rate regardless of stage at diagnosis. Patients exhibiting both MSI+ and LI+ tumors have more favorable disease-free survival rates. Both MSI and LI show promise as a combined prognostic marker and with further study may prove to be particularly useful in selecting patients with stage II disease for adjunctive therapy.