Analysis of long-term oncological results of clinical versus pathological responses after neoadjuvant treatment in locally advanced rectal cancer

The ultimate local failure rate after the watch-and-wait strategy for rectal cancer: a systematic review of literature and meta-analysis

BACKGROUND

We hypothesise that a high rate of tumour regrowth after the watch-and-wait (w&w) strategy may lead, despite salvage surgery, to a significant impairment of ultimate local control compared with immediate surgery.

MATERIALS AND METHODS

To test this hypothesis, we conducted meta-analyses of studies on the w&w strategy (both opportunistic and planned) with an ultimate local failure rate as an endpoint in three patient groups: (1) in all starting radio(chemo)therapy as potential w&w candidates, (2) in a subgroup starting w&w, and (3) in a subgroup with regrowth.

RESULTS

We identified eight studies for evaluation of local failure in group 1 (N = 837) and 36 studies in group 2 (N = 1914) and in group 3 (N = 439). The meta-analysis revealed an ultimate local failure rate of 8.0% (95% CI 4.8%-12.1%) in group 1 and 5.4% (95% CI 3.9%-7.1) in group 2. These rates are similar to those reported in the literature following preoperative chemoradiation and surgery. However, in the most unfavourable group 3 (with regrowth), the rate of ultimate local failure was 24.1% (95% CI 17.9%-30.9%), with the most common causes being patients' refusal of salvage total mesorectal excision (TME) (9.1%), recurrence after salvage TME (7.8%), distant metastases (4.1%), frailty (2.4%), and pelvic tumour unresectability (1.7%).

CONCLUSION

Nearly 25% of patients with regrowth (unfavourable subgroup) experienced ultimate local failure, primarily due to refusing salvage TME. The risk of ultimate local failure in patients initiating radio(chemo)therapy as potential w&w candidates, or in patients starting w&w, appears comparable to that reported after preoperative chemoradiation and surgery. However, this comparison may be biased, because w&w studies included more early tumours compared with surgical studies.

Cytokeratin 7 Expression and Mismatch Repair Status for Survival Prediction in Patients With Low Rectal Cancer After Neoadjuvant Therapy

BACKGROUND

More than half of the patients with locally advanced low rectal cancer exhibit no or minor response to nCRT. It is important to investigate the predictive and prognostic values of potential biomarkers in patients with locally advanced low rectal cancer receiving nCRT.

MATERIALS AND METHODS

This retrospective study included 162 patients with locally advanced low rectal cancer who underwent nCRT, followed by total mesorectal excision (TME) between 2016 and 2019. Cytokeratin 7 (CK7) expression and mismatch repair (MMR) status were determined by immunohistochemistry (IHC). Categorical variables were compared using the chi-square test. Overall survival (OS) and disease-free survival (DFS) curves were estimated using the Kaplan-Meier and Cox methods.

RESULTS

There were predominance significant differences in distance from anus margin (P < .0001) and circumferential extent of the tumor (P < .0001).CK7 positive expression was detected in 21 of the 162 patients (13%). The univariate and multivariate analysis revealed that patients whose tumors had CK7 positive expression had significantly shorter OS (HR = 3.878, P = .038; HR = 1.677, P = .035) and DFS (HR = 3.055, P = .027;HR = 3.569, P = .038) than those with CK7 negative expression. While patients with CK7 positive expression had a higher proportion of worse TRG compared with CK7 negative patients (P = .001). Patients with deficient mismatch repair (dMMR) just occupied a small proportion (8.6%), but there was still a close connection between the MMR status and recurrence after TME (P = .045). MMR status was an independent risk factor affecting the OS (HR = .307, P < .0001; HR = .123, P < .0001) and DFS (HR = .288, P < .0001; HR = .286, P < .0001) by univariate and multivariate analysis. But no significant difference in the proportion of TRG was observed between patients with dMMR and pMMR (P = .920).

CONCLUSIONS

The result confirms negative prognostic role of CK7-positive and dMMR statuses, which have potential predictive value for neoadjuvant chemoradiotherapy response. This provides opportunity to modify individualized treatment strategies for patients with different CK7 expression levels and dMMR statuses.

Neoadjuvant Short-Course Radiotherapy Followed by Consolidation Chemotherapy before Surgery for Treating Locally Advanced Rectal Cancer: A Systematic Review and Meta-Analysis

Neoadjuvant short course radiotherapy (SCRT) followed by consolidation chemotherapy (CCT) is an alternative treatment for locally advanced rectal cancer (LARC). We performed this systematic review and meta-analysis to explore the tumor response and oncological outcomes of this new approach compared to conventional chemoradiotherapy (CRT). An online search of the PubMed, Embase, and Cochrane Library databases was performed. This review included 7507 patients from 14 different cohorts. The pCR rate was higher with SCRT + CCT than that with CRT (RR: 1.60; 95% CI: 1.35−1.91; p < 0.01). SCRT + CCT provided a higher ypN0 response (RR: 1.06; 95% CI: 1.01−1.12; p = 0.02). There were no differences in R0 resection and positive CRM rates; however, more sphincter-preservation surgeries were performed in the SCRT + CCT arm (RR: 1.06; 95% CI: 1.01−1.11; p = 0.02). There was no difference in the OS and DFS between the SCRT + CCT and the CRT arms (OS: HR: 0.85, p = 0.07; DFS: HR: 0.88, p = 0.08). The compliance and toxicity were comparable between the SCRT and CRT groups. In the subgroup analysis, patients who underwent four or more cycles of CCT had better pCR and DFS events. Therefore, SCRT followed by consolidation chemotherapy might be an effective alternative treatment for LARC.

Endoscopy-Based Deep Convolutional Neural Network Predicts Response to Neoadjuvant Treatment for Locally Advanced Rectal Cancer

Background and Aims: Although the wait and watch (W&W) strategy is a treatment choice for locally advanced rectal cancer (LARC) patients who achieve clinical complete response (cCR) after neoadjuvant therapy (NT), the issue on consistency between cCR and pathological CR (pCR) remains unsettled. Herein, we aimed to develop a deep convolutional neural network (DCNN) model using endoscopic images of LARC patients after NT to distinguish tumor regression grade (TRG) 0 from non-TRG0, thus providing strength in identifying surgery candidates. Methods: A total of 1000 LARC patients (6,939 endoscopic images) who underwent radical surgery after NT from April 2013 to April 2021 at the Sixth Affiliated Hospital, Sun Yat-sen University were retrospectively included in our study. Patients were divided into three cohorts in chronological order: the training set for constructing the model, the validation set, and the independent test set for validating its predictive capability. Besides, we compared the model's performance with that of three endoscopists on a class-balanced, randomly selected subset of 20 patients' LARC images (10 TRG0 patients with 70 images and 10 non-TRG0 patients with 72 images). The measures used to evaluate the efficacy for identifying TRG0 included overall accuracy, sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and area under the receiver operating characteristic curve (AUROC). Results: There were 219 (21.9%) cases of TRG0 in the included patients. The constructed DCNN model in the training set obtained an excellent performance with good accuracy of 94.21%, specificity of 94.39%, NPV of 98.11%, and AUROC of 0.94. The validation set showed accuracy, specificity, NPV, and AUROC of 92.13%, 93.04%, 96.69%, and 0.95, respectively; the corresponding values in the independent set were 87.14%, 92.98%, 91.37%, and 0.77, respectively. In the reader study, the model outperformed the three experienced endoscopists with an AUROC of 0.85. Conclusions: The proposed DCNN model achieved high specificity and NPV in detecting TRG0 LARC tumors after NT, with a better performance than experienced endoscopists. As a supplement to radiological images, this model may serve as a useful tool for identifying surgery candidates in LARC patients after NT.

Prognostic Impact of An Integrative Landscape of Clinical, Immune, and Molecular Features in Non-Metastatic Rectal Cancer

Rectal Cancer (RC) is a complex disease that involves highly variable treatment responses. Currently, there is a lack of reliable markers beyond TNM to deliver a personalized treatment in a cancer setting where the goal is a curative treatment. Here, we performed an integrated characterization of the predictive and prognostic role of clinical features, mismatch-repair deficiency markers, HER2, CDX2, PD-L1 expression, and CD3-CD8+ tumor-infiltrating lymphocytes (TILs) coupled with targeted DNA sequencing of 76 non-metastatic RC patients assigned to total mesorectal excision upfront (TME; n = 15) or neoadjuvant chemo-radiotherapy treatment (nCRT; n = 61) followed by TME. Eighty-two percent of RC cases displayed mutations affecting cancer driver genes such as TP53, APC, KRAS, ATM, and PIK3CA. Good response to nCRT treatment was observed in approximately 40% of the RC cases, and poor pathological tumor regression was significantly associated with worse disease-free survival (DFS, HR = 3.45; 95%CI = 1.14-10.4; p = 0.028). High neutrophils-platelets score (NPS) (OR = 10.52; 95%CI=1.34-82.6; p = 0.025) and KRAS mutated cases (OR = 5.49; 95%CI = 1.06-28.4; p = 0.042) were identified as independent predictive factors of poor response to nCRT treatment in a multivariate analysis. Furthermore, a Cox proportional-hazard model showed that the KRAS mutational status was an independent prognostic factor associated with higher risk of local recurrence (HR = 9.68; 95%CI = 1.01-93.2; p <0.05) and shorter DFS (HR = 2.55; 95%CI = 1.05-6.21; p <0.05), while high CEA serum levels were associated with poor DFS (HR = 2.63; 95%CI = 1.01-6.85; p <0.05). Integrated clinical and molecular-based unsupervised analysis allowed us to identify two RC prognostic groups (cluster 1 and cluster 2) associated with disease-specific OS (HR = 20.64; 95%CI = 2.63-162.2; p <0.0001), metastasis-free survival (HR = 3.67; 95%CI = 1.22-11; p = 0.012), local recurrence-free survival (HR = 3.34; 95%CI = 0.96-11.6; p = 0.043) and worse DFS (HR = 2.68; 95%CI = 1.18-6.06; p = 0.012). The worst prognosis cluster 2 was enriched by stage III high-risk clinical tumors, poor responders to nCRT, with low TILs density and high frequency of KRAS and TP53 mutated cases compared with the best prognosis cluster 1 (p <0.05). Overall, this study provides a comprehensive and integrated characterization of non-metastatic RC cases as a new insight to deliver a personalized therapeutic approach.

Combination of extramural venous invasion and lateral lymph node size detected with magnetic resonance imaging is a reliable biomarker for lateral lymph node metastasis in patients with rectal cancer

PURPOSE

Pathological extramural venous invasion (EMVI) is defined as the active invasion of malignant cells into veins beyond the muscularis propria in colorectal cancer. It is associated with poor prognosis and increases the risk of disease recurrence. Specific findings on MRI (termed MRI-EMVI) are reportedly associated with pathological EMVI. In this study, we aimed to identify risk factors for lateral lymph node (LLN) metastasis related to rectal cancer and to evaluate whether MRI-EMVI could be a new and useful imaging biomarker to help LLN metastasis diagnosis besides LLN size.

METHODS

We investigated 67 patients who underwent rectal resection and LLN dissection for rectal cancer. We evaluated MRI-EMVI grading score and examined the relationship between MRI-EMVI and LLN metastasis.

RESULTS

Pathological LLN metastasis was detected in 18 cases (26.9%), and MRI-EMVI was observed in 32 cases (47.8%). Patients were divided into two cohorts, according to LLN metastasis. Multivariate analyses demonstrated that higher risk of LLN metastasis was significantly associated with MRI-EMVI (P = 0.0112) and a short lateral lymph node axis (≥ 5 mm) (P = 0.0002). The positive likelihood ratios of MRI-EMVI alone, LLN size alone, and the combination of both factors were 2.12, 4.84, and 16.33, respectively. Patients negative for both showed better 2-year relapse-free survival compared to other patients (84.4% vs. 62.1%, P = 0.0374).

CONCLUSIONS

MRI-EMVI was a useful imaging biomarker for identifying LLN metastasis in patients with rectal cancer. The combination of MRI-EMVI and LLN size can improve diagnostic accuracy.

A meta-analysis of the watch-and-wait strategy versus total mesorectal excision for rectal cancer exhibiting complete clinical response after neoadjuvant chemoradiotherapy

Background

Some clinical researchers have reported that patients with cCR (clinical complete response) status after neoadjuvant chemoradiotherapy (nCRT) could adopt the watch-and-wait (W&W) strategy. Compared with total mesorectal excision (TME) surgery, the W&W strategy could achieve a similar overall survival. Could the W&W strategy replace TME surgery as the main treatment option for the cCR patients? By using the meta-analysis method, we evaluated the safety and efficacy of the W&W strategy and TME surgery for rectal cancer exhibiting cCR after nCRT.

Methods

We evaluated two treatment strategies for rectal cancer with cCR after nCRT up to July 2021 by searching the Cochrane Library, PubMed, Wanfang, and China National Knowledge Infrastructure (CNKI) databases. Clinical data for primary outcomes (local recurrence, cancer-related death and distant metastasis), and secondary outcomes (disease-free survival (DFS) and overall survival (OS)) were collected to evaluate the efficacy and safety in the two groups.

Results

We included nine studies with 818 patients in the meta-analysis, and there were five moderate-quality studies and four high-quality studies. A total of 339 patients were in the W&W group and 479 patients were in the TME group. The local recurrence rate in the W&W group was greater than that in the TME group in the fixed-effects model (OR 8.54, 95% CI 3.52 to 20.71, P < 0.001). The results of other outcomes were similar in the two groups.

Conclusion

The local recurrence rate of the W&W group was greater than that in the TME group, but other results were similar in the two groups. With the help of physical examination and salvage therapy, the W&W strategy could achieve similar treatment effects with the TME approach.

Trial registration

Protocol registration number: CRD42021244032.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12957-021-02415-y.

Effect of mistletoe extract on tumor response in neoadjuvant chemoradiotherapy for rectal cancer: a cohort study

Background

Mistletoe extract, used as a complementary chemotherapeutic agent for cancer patients, has anticancer effects against various malignancies. The aim of the present study was to evaluate the effect of mistletoe extract (Abnoba Viscum Q®) on tumor responses to neoadjuvant chemoradiotherapy (NCRT) for locally advanced rectal cancer.

Methods

This study included patients with rectal cancer who underwent NCRT between January 2018 and July 2020. In the mistletoe group (MG), the patients were administered Abnoba Viscum Q® subcutaneously during chemoradiotherapy—maintained just before surgery. Patient demographics, clinical outcomes, histopathological outcomes, and terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end labeling (TUNEL) assay results were compared between the MG and non-mistletoe group (NMG). Two rectal cancer cell lines (SNU-503 and SNU-503R80Gy) were treated with Abnoba Viscum Q® to assess its mechanistic effects in vivo.

Results

Overall, the study included 52 patients (MG: n = 15; NMG: n = 37). Baseline demographics between the two groups were similar, except carbohydrate antigen 19-9 levels and tumor location from the anal verge. There was no difference in the clinical stage between the two groups. A better tumor response in the MG, relative to the NMG, was observed with respect to tumor regression grade (TRG), T stage, and overall tumor–node–metastasis stage. Tumor response was significantly better in the MG than in the NMG in terms of pathologic complete response rate (53.3% vs. 21.6%, P = 0.044), good TRG response (66.7% vs. 32.4%, P = 0.024), T downstaging (86.7% vs. 43.2%, P = 0.004), and overall downstaging (86.7% vs. 56.8%, P = 0.040). The toxicities during NCRT were minimal in both groups. More apoptotic cells were noted in MG samples than in the NMG samples on TUNEL staining. Cleaved caspase-3 level following treatment with Abnoba Viscum Q® was higher in SNU-503R80Gy cells than in SNU-503 cells.

Conclusion

Patients treated with chemoradiation combined with mistletoe extract showed better outcomes than patients not treated with mistletoe extract in terms of tumor responses. This diversity in treatment may improve the efficacy of NCRT, leading to better oncologic outcomes. Prospective and randomized studies with long-term follow-up are warranted to confirm and extend these results.

The assessment of risk factors for long-term survival outcome in ypN0 patients with rectal cancer after neoadjuvant therapy and radical anterior resection

BACKGROUND

The main negative prognostic factors in patients with rectal cancer after radical treatment include regional lymph node involvement, lymphovascular invasion, and perineural invasion. However, some patients still develop cancer recurrence despite the absence of the above risk factors. The aim of the study was to assess clinicopathological factors influencing long-term oncologic outcomes in ypN0M0 rectal cancer patients after neoadjuvant therapy and radical anterior resection.

METHODS

A retrospective survival analysis was performed on a group of 195 patients. We assessed clinicopathological factors which included tumor regression grade, number of lymph nodes in the specimen, Charlson comorbidity index (CCI), and colorectal anastomotic leakage (AL).

RESULTS

In the univariate analysis, AL and CCI > 3 had a significant negative impact on disease-free survival (DFS), disease-specific survival (DSS), and overall survival (OS). After the division of ALs into early and late ALs, it was found that only patients with late ALs had a significantly worse survival. The multivariate Cox regression analysis showed that CCI > 3 was a significant adverse risk factor for DFS (HR 5.78, 95% CI 2.15-15.51, p < 0.001), DSS (HR 7.25, 95% CI 2.25-23.39, p < 0.001), and OS (HR 3.9, 95% CI 1.72-8.85, p = 0.001). Similarly, late ALs had a significant negative impact on the risk of DFS (HR 5.05, 95% CI 1.97-12.93, p < 0.001), DSS (HR 10.84, 95% CI 3.44-34.18, p < 0.001), and OS (HR 4.3, 95% CI 1.94-9.53, p < 0.001).

CONCLUSIONS

Late AL and CCI > 3 are the factors that may have an impact on long-term oncologic outcomes. The impact of lymph node yield on understaging was not demonstrated.