[717] Chromogranin A Expression and Ki67 Index in Residual Rectal Cancer Treated with Preoperative Therapy.

Fabio Maria Vecchio, Vincenzo Arena, Maria Cristina Barba, Federica Castri, Giovan Battista Doglietto, Claudio Coco, Antonio Crucitti, Riccardo Ricci, Angela Corbosiero, Luca Valerio, Vincenzo Valentini. Catholic University, Rome, Italy

Background: This study was conducted to determine the significance of chromogranin A expression and Ki67 proliferative index in residual rectal cancer with good response after neoadjuvant therapy.
Design: The study population consisted of fifty-five patients with locally advanced rectal cancer treated with preoperative therapy and classified as Tumor Regression Grade (TRG) 3 according to the Mandard Score (Cancer 1994;73:2680-86), defined as regression greater than 50% with fibrosis outgrowing the tumor mass. Tumors expressing Chromogranin A were classified as either absent/low expression (≤30% cells staining positive) or high expression (>30% cells staining positive). The same cut-off was used to estimate the proliferative index by Ki67. The influence of these factors on disease-free survival was evaluated using Kaplan-Meier curves and Cox proportional hazards modeling.
Results: Of the fifty-five patients [33M/22F, mean age 58.3 (range 25 to 76)] 41 (75%) showed a Ki67 index > 30% and 14 (25%) showed a Ki67 index <30%. 10/55 (18%) expressed chromogranin A >30% and 45/55 (82%) expressed chromogranin A <30%. In multivariate analysis, a model for prediction of disease-free survival (five-ten years follow up) including the covariates chromogranin A expression >30%, age and Ki67 was found to be consistent with the assumption of proportional hazards. Statistical significance was reached for Chromogranin A (p=0.041) and age (p=0.019), while Ki67 displayed a “trend” (p=0.084) to be confirmed in a larger series.

Conclusions: This study demonstrates that expression of Chromogranin A is a predictive factor of disease-free survival in rectal cancer treated with neoadjuvant therapy in a regression model also including patient age and Ki67. Accordingly, chromogranin A expression may be considered as a variable useful for a better prognostic assessment of patients with TRG3 rectal cancer.
Category: Gastrointestinal

Wednesday, March 2, 2011 9:30 AM

Poster Session V # 54, Wednesday Morning


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