[672] Colon Cancer Nodal Staging Score: A Tool To Assess Adequacy of Nodal Harvesting in Pathology Practice

Aya Kuchiba, Paul Lochhead, Shuji Ogino. Dana-Farber Cancer Institute, Boston, MA; Brigham and Women's Hospital, Boston, MA

Background: Lymph node status remains the most important predictor of patient survival in stage I-III colon cancer. A nodal staging score (NSS) is a function of pT-stage and the number of examined lymph nodes, and is an estimate of the negative predictive value (NPV, a probability of true negative given a negative result) in colon cancer nodal staging. We examined whether NSS could be improved by additional variables, including tumor molecular features.
Design: We utilized 1139 stage I-III colon cancer cases, with available information on the node count and patient survival. We created a “modified” NSS using a subset of 688 colon cancers with available data on additional pathologic, and tumor molecular characteristics, including microsatellite instability (MSI) and KRAS, BRAF, and PIK3CA mutations. We compared performance of our modified NSS to the original NSS, using patient survival as an outcome measure.
Results: Modified NSS was a function of pT-stage, the node count, plus tumor mucinous component, tumor grade, MSI, and colorectal cancer family history. Modified NSS was associated with patient survival, (Figure 1) and the performance of modified NSS was similar to the original NSS, using survival data.

Concordance statistics for colon-cancer specific survival were 0.61 [95% confidence interval (CI), 0.49-0.73] and 0.60 (95% CI, 0.47-0.73) for modified and original NSS, respectively.
Conclusions: Both the original NSS and the modified NSS are valid tools to estimate NPV in nodal staging for colon cancer. Our data support the utility of the easily-calculable original NSS (as a function of pT stage and the node count) for stage I-II colon cancer in routine pathology practice. NSS can be used to refine the recommendations in nodal harvesting in colorectal cancer.
Category: Gastrointestinal

Wednesday, March 6, 2013 9:30 AM

Poster Session V # 89, Wednesday Morning


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