Discovery of New Histological Prognostic Factors in Rectal Adenocarcinocarcinoma Treated by Radiochemotherapy Followed by Total Mesorectum Excision
Aurelie Sannier, Jeremie Lefevre, Frederic Bretagnol, Dominique Cazals-Hatem, Yves Panis, Pierre Bedossa, Nathalie Guedj. Beaujon Hospital, Clichy, France, Metropolitan
Background: Radiochemotherapy (RCT) followed by surgical resection became treatment of choice for patients with locally advanced rectal cancer. Specimen pathological diagnosis determine prognosis and further clinical management of patients. The aim of our study was to identify new histological prognostic factors in a consecutive series of surgical specimens of patients treated by neoadjuvant RCT.
Design: 113 patients were included. Macroscopic and microscopic examinations were performed according to the AJCC recommendations, with some additional criteria as the presence of buds or calcifications in the tumor bed. Modified Rectal Cancer Regression Grade (m-RCRG) was assessed. Lymph node (LN) reshuffles as fibrosis, necrosis, calcifications or macrophagic infiltration were notified. LN metastasis regression grading was also evaluated regarding the percentage of residual tumor cells. Univariate and multivariate analyses were used to identify histological prognostic factors.
Results: Disease-free survival (DFS) was 69 % at a mean follow-up of 25.2±16 months [2-57]. In univariate analysis, ypTN stage, tumor budding, circumferential resection margin, invaded margin, vascular and perineural invasion were prognostic factors (p<0.05). In multivariate analysis, presence of calcifications in tumor bed (p=0.027) and small circumferential margin (p=0.032) were the only two independent factors of worse DFS. mRCRG was not correlated to DFS. However, among the 50 mRCRG1 tumors, DFS was significantly better in ypT0 patients than in other ypT stages (p=0.032). We observed LN reshuffles among ypN0 and ypN+ patients respectively in 6% and 94%. The mean percentage LN metastasis regression was 23±19% [2-70%]. Patients with at least or more of 30% of LN metastasis regression had a tendency to have a better DFS compared to patients with < 30% of LN metastasis regression (p=0.1).
Conclusions: Presence of calcifications in tumor bed is a new major prognostic factor described for the first time in rectal cancer. The presence of tumor buds at the edge of the tumor was confirmed to be of prognostic value. Lastly, ypT stage appears as a more reliable predictor of oncological outcome than the more reproducible histological tumor regression grade according to Bateman and al study. In our study, LN metastasis regression grade had a tendency to be correlated with DFS. However, further studies focusing specifically on LN metastasis regression are needed to confirm its potential prognostic value.
Tuesday, March 5, 2013 1:00 PM
Poster Session IV # 141, Tuesday Afternoon