[725] The Prognostic Value of Oncocytic Change and Dvorak Grade of Regression in Rectal Adenocarcinoma Treated with Neo-Adjuvant Chemoradiotherapy

P Roy, S Serra, R Chetty. University Health Network, Toronto, ON, Canada

Background: Neo-adjuvant chemoradiation (NACRT) is a standard treatment option for locally advanced rectal adenocarcinoma. Oncocytic change (OC) has been described in this context as a reflection of cytotoxic damage or cellular hypoxia induced by chemoradiation. The aim of this study was to asses the incidence of oncocytic change in the residual tumor and its possible significance on clinical outcome.
Design: 40 cases of rectal adenocarcinomas treated with NACRT followed by surgery were examined for degree of regression (DR) using Dvorak's regression scoring system and OC. The latter was expressed as a percentage of the entire tumor population. Progression-free survival (PFS) and overall survival (OS) were assessed using the Kaplan Meier curve. The impact of pre-operative and post-operative T and N status as well as DR and OC were assessed using the log-rank test.
Results: Only one case had a complete response (DR4), 12/40 and 10/40 had a partial response with DR3 and DR2, respectively, while 17/40 had poor response with DR1. OC content was <35% in 29/40 case and >35% in 11 cases. A definite predictive trend showed that patients with OC > 35% in residual tumor had a poorer prognosis. However, it was not significant in our small series (3yr PFS 75% in <35% vs 65% in >35%, p=0.2851). A similar non-significant relation was also noted with the DR and PFS (3yr PFS 59% in DR1/2 vs 90% in DR3/4, p=0.3495). The pre-operative T and N stage were not significant predictors of PFS or OS. However, the post-operative T stage showed a statistically significant impact (p=0.0018).
Conclusions: Our study is the first to correlate OC as a possible prognostic marker in rectal adenocarcinoma patients receiving NACRT. Though we found that post-operative T stage was the only significant prognostic factor, OC and DR showed a definite trend to predict outcome. Although non-significant in our study, this may have significance in a larger cohort of patients.
Category: Gastrointestinal

Tuesday, March 23, 2010 9:30 AM

Poster Session III # 108, Tuesday Morning


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