A Modified Classification of Prognostic Factors Based on Pathological Stage and Tumor Regression Grade in Patients with Rectal Cancer Who Receive Preoperative Chemoradiotherapy

Comparison of the diagnostic performance of changes in signal intensity and volume from multiparametric MRI for assessing response of rectal cancer to neoadjuvant chemoradiotherapy

AIM

To evaluate the change in signal intensity (SI) and volume (V) from multiparametric magnetic resonance imaging (MRI) for assessing the response of locally advanced rectal cancer (LARC) to chemoradiotherapy (CRT).

MATERIALS AND METHODS

Eight-two LARC patients who underwent pre- and post-CRT T2-weighted (T2W), apparent diffusion coefficient (ADC), and contrast-enhanced T1-weighted (ceT1W) MRI were retrospectively analyzed. The change of volume (%△V) and relative SI ratio (%△SIR) from each sequence were determined. All LARCs were confirmed pathologically and classified as tumor regression grade (TRG) -0, 1, 2,or 3. Descriptive statistics and receiver operating characteristic (ROC) analysis, with calculation of area under the curve (AUC), were used to compare the diagnostic performances.

RESULTS

Sixteen patients had TRG-0, 15 had TRG-1, 35 had TRG-2, and 16 had TRG-3. Except for ADC-%△SIR, the remaining %△V and %△SIR values on MR sequences had significant differences among the four groups. The %△V and %△SIR (alone or together) did not distinguish TRG-1 from TRG-2, nor TRG-2 from TRG-3; however, differences between other TRGs were identified by %△V and %△SIR. The combined use of ADC-%△V and T2W-%△SIR provided the best diagnostic performance in distinguishing of TRG-0 from TRG-2 (AUC: 0.954) and from TRG-3 (AUC: 1.000).

CONCLUSIONS

Preoperative MRI of LARC patients after CRT has high diagnostic value for determination TRG, and may therefore improve the selection of patients most suitable for surgery.

The concept and use of the neoadjuvant rectal score as a composite endpoint in rectal cancer

There is no universally accepted instrument to use as a validated surrogate endpoint for overall survival in phase 2 and phase 3 multimodal rectal cancer trials using chemoradiotherapy. Efforts are hampered by the inaccuracy of clinical TNM staging, the variability of indications for neoadjuvant treatment, and diverse definitions of tumour regression grade. Pathological complete response is commonly used, but fails to capture information from the majority of patients. The neoadjuvant rectal score categorises response and downstaging from the entire trial population to identify whether or not a novel treatment group in a chemoradiation trial is superior by predicting overall survival outcomes. Additionally, the neoadjuvant rectal score assesses the difference between initial clinical and pathological T stage and the presence or absence of nodal involvement after treatment. The neoadjuvant rectal score has been conceptually, but incompletely, statistically validated by two independent trial datasets. However, a fundamental weakness of the score is that no preoperative phase 3 trials in locally advanced rectal cancer in the past 20 years have provided a significant benefit in overall survival to statistically validate the neoadjuvant rectal score as a surrogate endpoint for overall survival. We review the robustness, practical value, applicability, generalisability, advantages, and disadvantages of the neoadjuvant rectal score as a surrogate endpoint for overall survival and recommend how this score could be improved and be acceptable as a standard endpoint in studies investigating neoadjuvant chemotherapy and chemoradiation in patients with rectal cancer.

Tumor-Infiltrating Lymphocytes in Biopsy Specimens Obtained 7 Days after Starting Chemoradiotherapy for Rectal Cancer Are Predictors of the Response to Chemoradiotherapy

BACKGROUND

Neoadjuvant chemoradiotherapy (nCRT) followed by total mesorectal excision surgery is a standard treatment for locally advanced rectal cancer (LARC). Tumor-infiltrating lymphocytes (TILs) have been reported to be associated with tumor response; however, this remains to be established. We previously reported that histological changes on biopsy specimens obtained 7 days after starting nCRT are strong predictors of response to nCRT.

METHODS

The subjects were 208 patients with LARC who received nCRT. TILs on hematoxylin-eosin staining together with immunohistochemical staining of lymphocyte surface markers including CD3, CD4, CD8, and FoxP3 were performed both on the biopsy specimens before and 7 days after starting nCRT.

RESULTS

The proportions of patients with high densities of CD3+, CD4+, CD8+, and FoxP3+ cells 7 days after starting CRT were significantly lower than the respective values before starting nCRT (p < 0.0001, p < 0.0001, p = 0.0023, and p = 0.0046). In biopsy specimens obtained before treatment, high-density CD4+ cells and FOXP3+ cells were significantly associated with tumor shrinkage rate. High-density FOXP3+ cells were significantly associated with marked tumor regression. In biopsy specimens obtained 7 days after starting treatment, high-density CD4+ cells were significantly associated with marked tumor regression, tumor regression grade 1, and tumor shrinkage rate. High-density FoxP3+ cells were significantly associated with marked tumor regression and tumor shrinkage rate.

CONCLUSIONS

In patients who received nCRT for LARC, the evaluations of immunohistochemical staining for CD4+ and FOXP3+ TILs were more intimately related to histological response to CRT and tumor shrinkage rates in biopsy specimens obtained 7 days after starting treatment than in biopsy specimens obtained before CRT.

The Prognostic Value of a Pathologic Complete Response After Neoadjuvant Therapy for Digestive Cancer: Systematic Review and Meta-Analysis of 21 Studies

BACKGROUND

Neoadjuvant therapy (NAT) before radical excision has become the preferred initial option for locally advanced digestive cancers such as esophageal cancer (EC), esophagogastric junction adenocarcinoma (EGJAC), gastric adenocarcinoma (GAC), rectal cancer (RC), and pancreatic cancer (PC). Although some patients reportedly achieve a pathologic complete response (pCR) after neoadjuvant therapy, the published data are inconsistent regarding whether pCR yields a survival benefit. The current meta-analysis was performed to assess the potential prognostic value of pCR after preoperative therapy for patients with digestive cancers.

METHODS

An extensive electronic search in PubMed, Web of Science, and the Cochrane Library was performed for relevant articles, from which data relative to independent correlations of pCR with overall survival (OS) and disease-free survival (DFS) were extracted for analysis. A random-effects model was used to calculate the pooled hazard ratios (HRs) with their corresponding 95% confidence intervals (CIs).

RESULTS

The study identified 6780 patients who met the inclusion and exclusion criteria. The results showed that pCR was significantly correlated with better OS (HR, 0.50; 95% CI, 0.43-0.58; P < 0.001) and DFS (HR, 0.49; 95% CI, 0.40-0.60; P < 0.001) for the digestive cancer patients who achieved pCR than for those who did not achieve pCR. Subgroup analysis showed that the correlation of pCR with OS was significant in EC (HR, 0.57; 95% CI, 0.47-0.69; P < 0.001), EGJAC/GAC (HR, 0.38; 95% CI, 0.17-0.86; P = 0.02), RC (HR, 0.48; 95% CI, 0.28-0.81; P = 0.006), and PC (HR, 0.41; 95% CI, 0.17-0.97; P = 0.04). In addition, the survival benefit for pCR patients was of similar magnitude, irrespective of the type of study, type of NAT, or ethnicity.

CONCLUSIONS

A pCR is correlated with favorable survival outcomes compared with a non-pCR for digestive cancer patients after NAT.

Impact of Tumor Regression Grade as a Major Prognostic Factor in Locally Advanced Rectal Cancer after Neoadjuvant Chemoradiotherapy: A Proposal for a Modified Staging System

There is ongoing debate regarding the significance of complete or near-complete response after neoadjuvant chemoradiotherapy (CRT) for rectal cancer. This study assessed the prognostic value of the Dworak tumor regression grade (TRG) following neoadjuvant CRT and surgery primarily in patients with pathological stage (ypStage) II and III rectal cancer. The records of 331 patients who underwent neoadjuvant CRT followed by total mesorectal excision between 2004 and 2015 were retrospectively reviewed. Patients were categorized as having a good response (GR, TRG 3/4, n = 122) or a poor response (PR, TRG 1/2, n = 209). At a median follow-up of 65 months, five-year disease-free survival (DFS) was higher in the GR group than in the PR group (91.3% vs. 66.6%, p < 0.001). Patients with a GR and ypStage II disease had a five-year DFS that was indistinguishable from that of patients with ypStage 0–I disease (92.3% vs. 90.7%, p = 0.885). Likewise, patients with a GR and ypStage III disease had a five-year DFS similar to those with ypStage II disease (76.0% vs. 75.9%, p = 0.789). A new modified staging system that incorporates grouped TRG (GR vs. PR) was developed. The prognostic performance of this modified stage and the ypStage was compared with the Harrell C statistic. C statistic of the modified stage was higher than that of the ypStage (0.784 vs. 0.757, p = 0.012). The results remained robust after multivariate Cox regression analyses. In conclusion, a GR to neoadjuvant CRT is an independent predictor of good DFS and overall survival and further stratifies patients so as to estimate the risk of recurrence and survival among patients with ypStage II and III rectal cancer.