[603] Evaluation of Tumor Regression on Primary Tumors and Corresponding Lymph Nodes of Locally Advanced Rectal Adenocarcinomas after Neoadjuvant Treatment. A Prospective Study of 254 Cases.

Frederic Bibeau, Helene Frugier, Julien Palasse, Christina Leaha, Amelie Gudin de Vallerin, Marie-Francoise Jourdan, Xavier Bodin, Veronique Perrault, Celine Cantos, Florence Boissiere-Michot. CRLCC Val d'Aurelle, Montpellier, France

Background: Tumor regression (TR) of locally advanced rectal adenocarcinomas after neoadjuvant treatment gives prognostic information and pathologic complete response (pCR) is associated with better outcome. Major TR may lead to conservative surgery while poor TR can isolate high risk patients. However, most of the studies about TR have concerned the primary tumor without considering lymph nodes evaluation and correlations on response between the 2 sites.
Design: We aimed to evaluate: 1) TR on primary tumor and corresponding lymph nodes after neoadjuvant treatment, 2) the impact of therapeutic options (chemoradiation versus radiotherapy or chemotherapy) on TR. 254 locally advanced rectal adenocarcinomas have been prospectively collected in a database according to standardized reports between 2006 and 2010. TR grade on primary was assessed according to the Dworak (Dw) grading: Dw 0: no regression, Dw 1: dominant residual tumor with morphologic alterations (necrosis, fibrosis, colloid response), Dw 2: dominant morphologic alterations with residual tumor, Dw 3: very few tumors cells with dominant morphologic alterations, Dw 4: pCR. Lymph nodes were classified as: sterilized, metastatic with morphologic alterations, metastatic with no morphologic alterations.
Results: Dw 0, 1, 2, 3, 4 were found in 4, 27, 29, 27 et 13 % of the cases, respectively. Chemoradiation was more often associated with major TR(Dw 2-4), than chemotherapy or radiotherapy alone (p<0.001). The rate of metastatic lymph nodes was lower in pCR than in tumors with partial (Dw 1-3) or no response (Dw 0) (p = 0.014). Sterilized lymph nodes were found in 12% of negative lymph nodes patients. They were more often encountered among primary tumors with major TR (Dw 2-4 vs Dw 0-1, p = 0.015). When primary tumor showed no features of TR, corresponding metastatic lymph nodes displayed no morphologic alterations. Colloid and major colloid (more than 50% of mucin pools) responses were observed in 35 % and 17% of primary tumors, respectively. Colloid response in the primary, whatever the extent of mucin pools, was significantly associated with colloid responses in lymph nodes (p<0.001).
Conclusions: These results indicate that TR is more important in case of chemoradiation. TR in primary tumor is significantly associated with TR in metastatic or sterilized lymph nodes. These data, which are not integrated to the available TR classifications, could better reflect the impact of induction treatment and lead to an optimized management of patients.
Category: Gastrointestinal

Wednesday, March 2, 2011 9:30 AM

Poster Session V # 49, Wednesday Morning


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