Online

ESTRO 2020

Session Item

Clinical track: Lower GI (colon, rectum, anus)
9306
Poster
Clinical
23:00 - 23:00
WHAT’S THE ROLE OF TUMOR REGRESSION GRADE (TRG) IN RECTAL CANCER: AN ISTUTUTIONAL EXPERIENCE
PO-1115

Abstract

WHAT’S THE ROLE OF TUMOR REGRESSION GRADE (TRG) IN RECTAL CANCER: AN ISTUTUTIONAL EXPERIENCE
Authors: Guaineri|, Annamaria(1)*[anna.guaineri@gmail.com];Triggiani|, Luca(1);Frassine|, Francesco(1);Imbrescia|, Jessica(1);Barbera|, Fernando(1);Vitali|, Paola(1);Terraneo|, Fabrizia(1);Pegurri|, Ludovica(1);Ranghetti|, Elena(1);Taddeo|, Alessandra(1);Magrini|, Stefano Maria(1);Buglione|, Michela(1);
(1)Spedali Civili di Brescia, Radiation Oncology, Brescia, Italy;
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Purpose or Objective

The neoadjuvant treatment with long-course radiotherapy and concomitant chemotherapy (NA-CRT) or with short-course radiotherapy followed by surgery is now the standard treatment in locally advanced rectal tumors.
A parameter that allows us to have a degree of prediction of the response to neoadjuvant treatment is TRG (tumor regression grade), which is always included in the histopathological report and which defines the degree of tumor regression. In the literature TRG has shown to predict outcome after NACRT.
The objective of this retrospective study is to confirm the prognostic value of the TRG, evaluating if there is a significant correlation with disease features and the main oncological outcomes.

Material and Methods

The TRG was evaluated in 133 patients with histological diagnosis of adenocarcinoma of the rectum using the Ryan classification system (0-No viable cancer cells, 1-Single cells or small groups of cancer cells, 2-Residual cancer outgrown by fibrosis, 3-many tumor cells with poor fibrosis/extensive residual neoplasia). The patients undergo,from May 2004 to April 2017, a neoadjuvant treatment with long-course radiotherapy associated with fluoropyrimidine chemotherapy and subsequently undergo surgery. Disease basal and after surgery characteristics were analyzed and related to TRG and OS, DFS, DSS, MFS and LRFS. (SPSS® 25.0).

Results

133 patients were treated. Median age 64,5 (68%<70aa and 31,6%>70aa). Ninety-two patients (69.2%) hadcT3 disease, and 28 (21,1%) cT2; 10 patients hadcN1a, 42 cN1b (Tab1). After surgery the most patients were pT3(n=63, 51,1%), the other pT2 n=42(31,6%); 87 patients (65,4%) were pN0, 14 (10,5%) pN1a, 14 (10,5%) pN1b, 6 (4,5%) pN2a, 6 (4,5%) pN2b(Tab1. Staging before treatment was performed with TC and EUS (n=42), only TC (n=48), RMN (n=42). Chemotherapy was 5-FU in 126 cases and Capecitabine in 20 cases, 2 other. Median days between Rt and surgery were 46 days. For the 133 patients analyzed, 25 (18.8%) showed a TRG 3, 49 (36.8%) a TRG 2, 46 (34.6%) a TRG 1 and 13 (9.8%) a TRG 0.
The TRG was statistically related to DFS (p <0.001), to MFS (p = 0.003) but not to LRFS (p = 0.85) and to DSS (p = 0.132),indeed patients bad responders (TRG 4) have a minor time to relapse locally and for distant metastasis. At the multivariate analysis only the TRG and the pathological stage were significantly correlated with DFS. The Cox regression (p = 0.033) showed an increased risk for relapse in patients with TRG 4 compared to good responders (HR 5.3) in relation to DFS.

Conclusion

The TRG is confirmed as a fundamental parameter in determining the outcomes in patients with rectal cancer subjected to NA-CRT. A prospect still open for the future is the integration of the TRG in the staging of the patient to identify the classes of patients at risk and worthy of adjuvant therapy.