Pathologic Tumor Regression Grade (TRG) and 10-Year Outcomes in 502 Patients with Rectal Cancer Treated with Preoperative Therapy
FM Vecchio, MC Barba, MA Gambacorta, R Ricci, L Santoro, B Diletto, M Balducci, C Coco, GB Doglietto, A Crucitti, B Barbaro, V Valentini. Catholic University, Rome, Italy
Background: Pathologic downstaging in rectal cancer after preoperative therapy is associated with improved long term outcomes. The pathologic assessment of tumor regression grade (TRG) provides valuable prognostic informations and can be used in selecting patients for a more conservative procedure and in identifying high-risk patients who need additional therapy.
Design: The present study was undertaken to examine the relationship between TRG and 10-year outcomes in 502 patients with locally advanced rectal cancer treated with preoperative therapy. TRG was defined in five grades (according to the Mandard score, Cancer 1994; 73: 2680-2686) ranging from 1 (complete regression) to 5 (absence of regressive changes). 10-year outcomes were expressed by three parameters: cancer specific survival (CSS), local control (LC) and distant progression (DM).
Results: Of the 502 patients, 125 (24.9%) were TRG 1, 90 (17.9%) were TRG 2 (rare residual cancer cells), 177 (35.3%) were TRG 3 (fibrosis outgrowing residual cancer), 102 (20.3%) were TRG 4 (residual cancer outgrowing fibrosis) and 8 (1.6%) were TRG 5. To simplify the analysis, TRG was combined in three groups: TRG1, TRG2-3, TRG4-5. By covariate analysis, TRG1 was associated with 10-year CSS in 89±5.3% of cases at variance of TRG2-3 (84±4.6%) and TRG4-5 (46±10.3%), with a P-value = 0.002. 10-year LC was 97±1.5% in TRG1, 91±2.2% in TRG2-3 and 77±5.6% in TRG4-5, with a P-value = 0.001. 10-year DM was 10.7±3.1% in TRG1, 21,7±3.2% in TRG2-3 and 50.2±6.0% in TRG4-5 (P-value < 0.001).
Conclusions: This study, based on a very large group of patients with long term follow-up, demonstrates that TRG is a predictor for cancer specific survival, local control and distant progression after preoperative therapy in locally advanced rectal cancer patients. Moreover, covariate analysis indicates that TRG score can be simplified in three grades: 1, complete regression with absence of tumor cells, 2, incomplete regression with fibrosis predominant on cancer cells, 3, absent or poor regression with residual cancer outgrowing fibrosis .
Tuesday, March 23, 2010 9:30 AM
Poster Session III # 125, Tuesday Morning