Can tumor regression grade influence survival outcome in ypT3 rectal cancer?

An investigation into tumor regression grade as a parameter for locally advanced rectal cancer and 5-year overall survival rate

PURPOSE

The standard treatment for locally advanced rectal cancer (LARC) is neoadjuvant chemoradiation (nCRT) followed by surgery. Several parameters are associated with patient survival in LARC. One of these parameters is tumor regression grade (TRG); however, the significance of TRG remains controversial. In this study, we aimed to examine the correlations of TRG with 5-year overall (OS) and relapse-free survival (RFS) and identify other factors that influence the survival rates in LARC after nCRT followed by surgery.

METHODS

This retrospective study included 104 patients diagnosed with LARC who underwent nCRT followed by surgery at Songklanagarind Hospital from January 2010 to December 2015. All patients received fluoropyrimidine-based chemotherapy at a total dose of 45.0 to 50.4 Gy in 25 daily fractions. Tumor response was evaluated using the 5-tier Mandard TRG classification. TRG was categorized into good (TRG 1-2) and poor (TRG 3-5) responses.

RESULTS

TRG (classified by either the 5-tier classification system or the 2-group classification system) was not correlated with 5-year OS or RFS. The 5-year OS rates were 80.0%, 54.5%, 80.8%, and 67.4% in patients with TRG 1, 2, 3, and 4, respectively (P=0.22). Poorly differentiated rectal cancer and systemic metastasis were associated with poor 5-year OS. Intraoperative tumor perforation, poor differentiation, and perineural invasion were correlated with inferior 5-year RFS.

CONCLUSION

TRG was probably not associated with either 5-year OS or RFS; however, poor differentiation and systemic metastasis were strongly associated with poor 5-year OS.

Magnetic resonance imaging tumor response score (mrTRS) predicts therapeutic effect and prognosis of locally advanced rectal cancer after neoadjuvant chemoradiotherapy: A prospective, multi-center study

BACKGROUND AND PURPOSE

The MRI-assessed tumor regression grade (mrTRG) is limited due to its subjectivity and poor consistency on pathological tumor regression grade (pTRG). A new MRI criterion was established to predict the prognosis of locally advanced rectal cancer (LARC).

MATERIALS AND METHODS

The new MRI criterion magnetic resonance imaging tumor response score (mrTRS) was based on the retrospective sample of 214 LARC patients (unpublished data). Subsequently, 878 LARC patients were enrolled for a prospective, multicenter study. Baseline and postoperative MRI were obtained, and imaging features were measured by collecting the pathological, clinical and follow-up data. Kaplan-Meier method with log-rank estimate and multivariate cox regression model was used to determine the prognosis of mrTRS in LARC patients with neoadjuvant chemoradiotherapy (NACRT). The predictive capability of 3-year prognosis between mrTRS and mrTRG was determined by time-dependent ROC curves.

RESULTS

The results demonstrated that mrTRS acted as an independent predictor of survival outcomes. mrTRS stratified by good and moderate responders showed significantly lower risk of death (HR = 0.04, 95%CI 0.01-0.31; HR = 0.35, 95%CI 0.23-0.52), distant metastasis (HR = 0.25, 95%CI 0.13-0.52; HR = 0.42, 95%CI 0.30-0.58), and local recurrence when compared with poor responders(HR = 0.01 95%CI 0.23-0.52;HR = 0.38, 95%CI 0.16-0.90). In contrast, no significant difference was observed among mrTRG stratified groups. Excellent and substantial interobserver agreement for mrTRS and mrTRG evaluation was observed (κ = 0.92 and 0.62), respectively.

CONCLUSION

mrTRS can serve as an effective predictor for assessing tumor regression grade in LARC patients with NACRT.