International Journal of Radiation Oncology*Biology*Physics
Clinical investigationRectumThe relationship of pathologic tumor regression grade (TRG) and outcomes after preoperative therapy in rectal cancer
Introduction
In the last several years, a number of studies examining the use of preoperative chemoradiation (CMT) in patients with cT3–4 rectal cancer have reported pathologic complete response rates (pCR) of 9–29%, as well as an increased ability to perform sphincter-sparing surgery (1, 2, 3, 4, 5, 6).
Many series report that patients who achieve a pCR after preoperative CMT, independent of their initial clinical T and N stage, have improved long-term outcomes, including local control, metastases-free survival, and overall survival (6, 7, 8, 9, 10, 11, 12). In patients who achieve less than a pCR, there is heterogeneity in definitions and techniques of identifying and scoring the presence of residual tumor after preoperative CMT. For example, stage pT3 has been defined as responses ranging from gross disease remains in the perirectal fat to those with a few foci of microscopic residual disease outside the bowel wall. Most series report that the degree of response is predictive of outcomes (6, 10). For example, Wheeler et al. have suggested that patients with only microscopic foci in the mesorectum had a better prognosis compared with patients with T3 (transmural) disease (13).
The aim of this study is to evaluate the relationship between the tumor regression grade (TRG) pathologic scoring system, which is based on the characteristics of the disposition of residual neoplastic cells in the specimen, and 5-year outcomes in patients with rectal cancer treated with preoperative radiation therapy with or without concomitant chemotherapy.
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Methods and materials
A total of 216 patients with cT3–4 and/or N* rectal cancer were treated with preoperative radiation with or without concurrent chemotherapy between March 1990 and February 2000 in the Department of Radiation Oncology at the Catholic University, Rome, Italy. For this analysis, 144 patients were identified who had a minimum follow-up of 3 years and the availability of the pathologic specimen for the determination of TRG score. The remaining 72 patients were excluded because of inadequate
Patient characteristics (pretreatment)
A total of 144 patients (96 male, 48 female) with a minimum follow-up of 3 years had TRG analysis of pathologic specimen. The median age was 64 years (range, 25–81 years). The tumor stage at initial (pretreatment) diagnosis and tumor grade are seen in Table 1.
The median length of the tumor was 50 mm (SD, 17.6, range, 10–150 mm). The number of quarters of rectal wall invaded by the tumor were measured on CT scan images; the results are as follows: 1 wall, 8 (6%); 2 walls, 69 (48%); 3 walls, 17
Discussion
Retrospective data suggest that pathologic downstaging after preoperative radiotherapy with or without concomitant chemotherapy is associated with improved outcomes (6, 7, 8, 9, 10, 12). Patients with pT0–2 stage disease after preoperative therapy have local failure rates of 0–6% and 5-year survivals of 90–100%. However, there is heterogeneity in the definitions as well as the techniques of identifying and scoring the presence of residual tumor after preoperative therapy. Therefore, we have
Conclusion
Tumor regression grade seems to be a prognostic factor for disease-free survival in patients receiving preoperative therapy for rectal cancer. In addition, it is a prognostic factor for local failure, metastasis-free survival, and overall survival. Given the ability of TRG to predict those patients with N* disease, in combination with other clinicopathologic factors, it may be helpful after preoperative therapy in selecting patients for a more conservative procedure, such as local excision
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