Pathologic evaluation of the response of mesorectal positive nodes to preoperative chemoradiotherapy in patients with rectal cancer

Post-Chemoradiation Metastatic, Persistent and Resistant Nodes in Locally Advanced Rectal Cancer: Metrics and Their Impact on Long-Term Outcome

BACKGROUND

The purpose of this study was to evaluate the long-term oncological progression pattern of locally advanced rectal cancer patients with post-neoadjuvant nodal metastatic disease (ypN+) and correlate potential prognostic features associated with proven radiochemoresistant nodal biology.

METHODS

Individual patient data (100 variables) from a 20-year consecutive single-institution multidisciplinary experience (1995-2015), delivering multimodal therapy to rectal cancer patient candidates for radical treatment, including a neoadjuvant component and surgical resection with or without intraoperative radiotherapy followed by optional adjuvant chemotherapy. The ypN+ disease data was registered in the context of initial staging categories post-neoadjuvant T status (ypT).

RESULTS

Data on 487 patients showed histologically confirmed diagnoses of metastatic nodal disease in 108 specimens (ypN+, 22.1). There was a significant age difference (p = 0.009) between the ypN groups: age ≥ 65 was 57.6% in pN0 and 43.5% in ypN+ and patients aged < 65 constituted 42.4% of pN0 and 56.5% of ypN+. According to the clinical stage there were statistically significant differences (p = 0.001) in the categories' distribution: ypN+ patients 10.8% were stage II and 89.2% were stage III. Univariant analysis on outcome variables showed statistically significant differences in overall survival at 7 years (63.8% vs. 55.7%, p = 0.016) disease-free survival (DFS) (78% vs. 53.8%, p = 0.000) and local recurrence-free survival (LRFS) (93.6% vs. 84%, p = 0.002).

CONCLUSIONS

The presence of nodal metastases (ypN+) after neoadjuvant therapy containing long-course pelvic irradiation severely impacts the long-term outcome for patients with locally advanced rectal cancer and correlates with multiple clinical and therapeutic variable metrics. Implementation of local and systemic therapies should be adapted and intensified in relation to the finding of ypN+ category in surgical specimens.

Lymph node regression grading of locally advanced rectal cancer treated with neoadjuvant chemoradiotherapy

Neoadjuvant chemoradiotherapy (nCRT) and total rectal mesenteric excision are the main standards of treatment for locally advanced rectal cancer (LARC). Lymph node regression grade (LRG) is an indicator of prognosis and response to preoperative nCRT based on postsurgical metastatic lymph node pathology. Common histopathological findings in metastatic lymph nodes after nCRT include necrosis, hemorrhage, nodular fibrosis, foamy histiocytes, cystic cell reactions, areas of hyalinosis, residual cancer cells, and pools of mucin. A number of LRG systems designed to classify the amount of lymph node regression after nCRT is mainly concerned with the relationship between residual cancer cells and regressive fibrosis and with estimating the number of lymph nodes existing with residual cancer cells. LRG offers significant prognostic information, and in most cases, LRG after nCRT correlates with patient outcomes. In this review, we describe the systematic classification of LRG after nCRT, patient prognosis, the correlation with tumor regression grade, and the typical histopathological findings of lymph nodes. This work may serve as a reference to help predict the clinical complete response and determine lymph node regression in patients based on preservation strategies, allowing for the formulation of more accurate treatment strategies for LARC patients, which has important clinical significance and scientific value.

Lymph Node Regression to Neoadjuvant Chemoradiotherapy in Patients with Locally Advanced Rectal Cancer: Prognostic Implication and a Predictive Model

AIM

Currently, few studies have focused on the prognostic impact of lymph node regression to neoadjuvant chemoradiotherapy (NCRT) in rectal cancer. This study aimed to explore the prognostic impact of lymph node regression grade (LRG) in patients with locally advanced rectal cancer (LARC) following NCRT and radical surgery and develop a predictive nomogram for disease-free survival (DFS).

METHODS

LARC patients undergoing NCRT and radical surgery between 2013 and 2014 were enrolled and divided into LRG low (≤ 2), middle (3-9), and high (≥ 10) groups. Clinicopathological characteristics and survival outcomes were compared. Predictors for DFS were identified by Cox regression analysis, and a nomogram was constructed.

RESULTS

A total of 257 LARC patients were eligible, including LRG low (n = 149), middle (n = 59), and high (n = 49) groups. Higher LRG score was associated with higher TRG, more advanced ypT and ypN stages, and poorer OS and DFS (all P < 0.001). Cox regression analysis demonstrated that tumor differentiation (poor and anaplastic, HR = 2.048, P = 0.048), ypTNM stage (HR = 2.389, P = 0.015), and LRG-sum (HR = 1.020, P = 0.029) were independent prognostic determinants for DFS after NCRT. A nomogram for DFS was developed with a C-index of 0.68 (95%CI 0.64-0.72).

CONCLUSION

LRG is an important prognostic indicator for DFS in LARC patients after NCRT. A predictive nomogram based on LRG was developed to guide more tailored adjuvant treatment and surveillance.

The prognostic significance of the treatment response of regional lymph nodes and the refinement of the current TNM staging system in locally advanced rectal cancer after neoadjuvant chemoradiotherapy

The current TNM staging system uses the same category definitions for both rectal cancer patients with and without neoadjuvant chemoradiotherapy (NCRT). However, ypTNM stage, especially ypN stage does not predict patient survival after NCRT well. Whether tumor regression in lymph nodes (LRG) may improve the prediction has not been well studied. In total, 358 patients with rectal cancer who received NCRT followed by radical resection were recruited from 2004 to 2015, and the median follow‐up time was 57.5 months. The main outcome measure was disease‐free survival (DFS). In univariate analysis, factors associated with DFS were ypT stage, ypN stage, number of negative lymph nodes (NLN), lymph node ratio (LNR), tumor regression grade (TRG), M‐TTRG (modified ypT stage by combining ypT stage and TRG), maximum LRG (LRGmax), sum score of LRG (LRGsum), LRG ratio (average value of LRGsum), and M‐NLRG (modified ypN stage by combining LRGmax and LNR). In the multivariate Cox regression analysis, M‐TTRG and M‐NLRG (p < 0.001 and p = 0.030, respectively) were significantly associated with DFS. The estimated 5‐year DFS rates were 86.6%, 60.3%, and 36.4% for patients with M‐NLRG‐0, M‐NLRG‐1, and M‐NLRG‐2, respectively (p < 0.001). A significant difference in survival was observed among patients with NCRT after incorporating TRG and LRG simultaneously into the current ypTNM staging system (p < 0.001). LRG was an important prognostic factor in rectal cancer patients treated with NCRT and could refine the ypTNM staging system. The modified ypTNM staging system in combination with LRGmax, LNR, and TRG could improve the DFS prediction in each subset of patients.

YpN0 rectal cancer patients with sterilized lymph nodes after neoadjuvant chemoradiotherapy are of greater risk of recurrence

BACKGROUND

Indication for adjuvant chemotherapy in ypN0 rectal cancer patients after chemoradiotherapy (CRT) is debated. The clinical significance of the presence of sterilized lymph nodes (LNS) in ypN0 patients remains to be determined.

AIMS

To assess the prognostic value of LNS in ypN0 rectal cancers after neoadjuvant CRT.

METHODS

From 2006-2016, 235 patients underwent TME surgery for non-metastatic mid-low rectal cancer after CRT. A lymph node was considered sterilized if there were signs of treatment response (fibrosis, necrosis or mucus) without residual tumor cells.

RESULTS

180 patients (77%) were classified ypN0 and 55 (23%) ypN+. LNS was present in 20 patients (9%). In ypN0 patients, 5-year OS was similar between patients with and without LNS. In contrast, 5-year DFS was significantly lower in ypN0/LNS + patients (58% vs. 78%, p = 0.043) and was similar to those staged ypN+. In multivariate analysis, two factors were independent predictors of DFS: mesorectal grading (OR = 3.14; 95%CI: 1.10-8.34; p = 0.033) and the presence of LNS (OR = 3.93, 95% CI: 1.06-11.81, p = 0.042) CONCLUSION: The presence of LNS in ypN0 rectal cancer after neoadjuvant CRT is associated with an increased risk of recurrence and may be taken into account for the discussion of adjuvant chemotherapy.

Model predicting the ypN0 status after good response to chemoradiotherapy in rectal cancer

BACKGROUND

The purpose of this study was to identify the predictive factors for ypN0 status in tumors with good pathologic response to chemoradiotherapy (CRT).

METHODS

A retrospective chart review was conducted on patients at two tertiary cancer center who underwent rectal resection after good response to CRT between 2000 and 2013.

RESULTS

No preoperative treatment (oxaliplatin use, radiotherapy boost of 5,4 Gy, delay CRT-surgery) impacted on the ypN status. In the multivariate analysis, only a ypT<3 (HR 7.5 [2,9-19.5]) was significant and no lymphovascular invasion (HR 8,9 [1.6-49.8]) was limited to significance.The best model predicting the ypN0 status used only the ypT status<3. The major part (92.2%) of patients with ypT0-2 tumors had no LN invasion.

CONCLUSION

The risk of lymph node involvement metastases was only 7.8% for the patients with an ypT0-2 status. A fullthickness transanal resection coud be the futur treatment of these patients.

Is the pathological regression level of metastatic lymph nodes associated with oncologic outcomes following preoperative chemoradiotherapy in rectal cancer?

Purpose

The oncologic impact of the lymph node (LN) regression level after preoperative chemoradiotherapy (PCRT) has not been thoroughly evaluated. Hence, this study aimed to examine whether the regression level of metastatic LNs following PCRT is associated with oncologic outcomes in rectal cancer.

Results

The optimal number of cut points for LRG sum was determined to be three. The three LRG groups demonstrated different distributions according to the ypT and ypN stages (p < 0.001 for both). However, the distribution of the LRG groups was not associated with the TRG of the primary tumor (p = 0.527). The RFS significantly differed according to the LRG groups (p = 0.001). Moreover, the differences in RFS remained when the LRG groups were analyzed within each separate ypN stage. The LRG group was confirmed as a factor associated with RFS in the multivariate analysis (p=0.018), while the ypN stage was not (p=0.4).

Patients and Methods

We analyzed the outcomes of 142 rectal cancer patients diagnosed with ypN1 disease after PCRT followed by radical resection. The pathological responses of the primary tumor and LNs to PCRT were evaluated using the tumor regression grade (TRG) and LN regression grade (LRG), respectively. The impact of LRG on recurrence-free survival (RFS) was analyzed. The K-adaptive partitioning for survival data method was applied to determine the optimal number of cut points for the LRG-sum and the optimal number of subgroups.

Conclusion

The LRG as an indicator of response to PCRT should be considered as a prognostic determinant in rectal cancer patients. Future large-scale prospective studies are needed to confirm this finding.

A single institution's long-term follow-up of patients with pathological complete response in locally advanced rectal adenocarcinoma following neoadjuvant chemoradiotherapy

PURPOSE

This paper aimed to study the long term follow-up of patients with primary rectal adenocarcinoma receiving neoadjuvant chemoradiotherapy who obtained a pathological complete response (pCR) and identify factors predicting complete response.

METHODS

Retrospective review of notes, histology, pre-operative full blood count and imaging of patients with primary rectal adenocarcinoma diagnosed in our institute from 2000 to 2012 from a prospectively maintained database were used. SPSS version 22.0 was used for statistical analysis.

RESULTS

Three hundred eighty patients diagnosed with primary rectal adenocarcinoma were identified, 277 received neoadjuvant chemoradiotherapy followed by curative resection. Forty-six patients obtained a pCR (ypT0N0) with no local recurrence and two metastatic recurrences on follow-up. Patients with a pCR have a significantly improved overall survival and disease-free survival compared to a non-pCR (150.0 and 136.1 vs 77.5 and 84.7 months, p = 0.001). On univariate analysis, increased tumour height above anal verge, low lymph node yield, high pre-operative haemoglobin and a low neutrophil-lymphocyte ratio are significant factors identifying a pCR. Multivariable analysis of the above factors confirmed tumour height above anal verge as significant in obtaining a pCR.

CONCLUSION

Patients with rectal adenocarcinoma who develop a pCR following neoadjuvant chemoradiotherapy have improved overall and disease-free survival. We have identified distance from anal verge, low lymph node yield, high pre-operative haemoglobin and low neutrophil-lymphocyte ratio as significant predictors of developing a pCR.

Is it time to rethink the rule of total mesorectal excision? A prospective radiological and pathological study in 49 consecutive patients with mid-rectal cancer

AIM

Total mesorectal excision (TME) after neoadjuvant chemoradiotherapy is the standard treatment for T3-T4 and/or N+ mid-rectal tumours, regardless of the exact tumour level. This leads to optimal oncological results but possible impaired functional results. Reducing rectal excision could reduce the functional drawbacks. This study prospectively assessed the risk of N+ or other mesorectal tumour deposit (OTD) below the tumour level by magnetic resonance imaging (MRI) performed after chemoradiotherapy and pathological examination of the TME specimen.

METHOD

Consecutive patients with mid-rectal cancer who underwent TME after chemoradiotherapy were included. A prospective evaluation by postchemoradiotherapy MRI and pathological examination was performed to assess the location of N+ nodes and/or OTDs.

RESULTS

Of 49 consecutive patients, 27 (55%) presented with nodes on postchemoradiotherapy MRI. However, only 12 nodes (size 2-4 mm) in 9 patients (18%) were under the tumour level. On pathological examination, 717 total lymph nodes were found, with 37 N+ and 22 OTD. According to the tumour level: (i) above tumour level, 21/453 nodes were N+ and 6 OTD; (ii) at tumour level, 16/166 nodes were N+ and 15 OTD; (iii) below tumour level, 0/98 nodes (0%) was N+ and only 1 OTD (2%) was noted at 2 cm below tumour level.

CONCLUSION

After chemoradiotherapy, N+ and/or OTD located under the level of the rectal cancer seems to be a very rare event. A postchemoradiotherapy MRI could help detect such patients. For others patients, conservation of the lower rectum with only a subtotal mesorectal excision could possibly improve function.

Prognostic significance of tumor regression in lymph nodes after neoadjuvant therapy for rectal carcinoma

Neoadjuvant therapy (NAT) is mainly indicated for locally advanced rectal carcinoma. Many reports have shown that regression of the primary tumor is a prognostic factor. However, few reports to date have analyzed the potential prognostic significance of lymph node regression in rectal carcinoma. The aim of the present study is to describe the pattern of tumor regression in lymph nodes after NAT for rectal carcinoma and its potential prognostic significance. We have retrospectively reviewed 106 cases of rectal carcinoma treated at a single institution. We have retrieved data from the patients and reviewed the histopathological slides to evaluate tumor regression both of the primary tumor and of LN metastases. Prognosis has been defined both in terms of disease-free survival (DFS) and disease-specific survival (DSS). Of the patients, 16% showed complete response of the primary tumor, while 24% showed poor response, according to the CAP regression grading system. Absence of lymph node involvement after therapy was found in 80% of the patients (ypN0 cases), while 20% were ypN+. We reviewed 639 LN; 85 were involved by tumor, and 170 showed histological signs of tumor regression. The main pattern of tumor regression in lymph nodes was fibrosis (66.3%), followed by hystiocytosis (29.1%) and mucin pools (4.6%). We found histological signs of regression in 57% of ypN0 cases and 76% of ypN+ cases. We found a significant association between regression grade of the primary tumor and of lymph node metastases. For ypN0 patients with persistence of the primary tumor after NAT, the median DFS was significantly shorter in patients showing tumor regression in the LN. In a Cox multivariate survival model for DFS, this prognostic influence was independent of the regression grade of the primary tumor and also of the ypTNM stage. We found no significant association between any factor and DSS. The pattern of tumor regression in lymph nodes was not significantly associated with prognosis. Tumor regression in lymph nodes is an important prognostic factor in rectal carcinoma after NAT and should be specifically looked for and included in pathology reports.

The short-term outcomes of induction SOX (S-1 + oxaliplatin) ± cetuximab chemotherapy followed by short-course chemoradiotherapy in patients with poor-risk locally advanced rectal cancer

PURPOSE

To evaluate the safety and efficacy of induction SOX (S-1 + oxaliplatin) ± cetuximab chemotherapy followed by short-course chemoradiotherapy and surgery in patients with poor-risk locally advanced rectal cancer.

METHODS

We enrolled eligible patients with poor-risk rectal cancer defined as T3 lower rectal cancer with mesorectal fascia involvement, T4a or T4b tumors or cases with lateral lymph node swelling. The primary endpoint was a pathological complete response (pCR), and the secondary endpoints were the objective response rate (ORR) and the pathological high response rate (Grade 2 plus 3).

RESULTS

Twenty eligible patients were enrolled. The majority (75.0 %, 15/20) of the patients completed four cycles of induction chemotherapy, and all patients completed the radiotherapy (25 Gy/10 fractions/5 days). The global rate of Grade 3-4 toxicities was 30.0 % (6/20 patients). The ORRs were 85.0 % (17/20) and 95.0 % (19/20) in the patients who underwent R0 and R1 resection, respectively. The pathological high response rate was 70.0 % (14/20) and the pCR was 10.0 % (2/20).

CONCLUSION

The regimen of induction SOX (S-1 + oxaliplatin) ± cetuximab chemotherapy followed by short-course chemoradiotherapy is safe and is associated with good tumor regression in patients with poor-risk locally advanced rectal cancer.

Comparison of the pathological response of the mesorectal positive nodes between short-course chemoradiotherapy with delayed surgery and long-course chemoradiotherapy in patients with rectal cancer

BACKGROUND

The aim of this study was to compare the pathological response of mesorectal positive nodes between short-course chemoradiotherapy with delayed surgery (SCRT-delay) and long-course chemoradiotherapy (LC-CRT) in patients with rectal cancer.

METHOD

The resected primary tumor specimens following the two different approaches were assessed utilizing the tumor regression grade (TRG 0-4), and each positive lymph node was assessed according to the lymph node regression grade (LRG 1-3), with TRG 4 and LRG 3 indicating total regression. The lymph node sizes were measured to elucidate any correlation with LRG scores.

RESULTS

Seventy-four patients with ypN-positive rectal cancer had 220 positive lymph nodes following the SCRT-delay, and 48 patients had 141 positive lymph nodes following the LC-CRT. The distribution of LRG 1/2/3 in the two groups was 123/72/25 and 60/31/50 (p < 0.001), respectively, and the distribution of TRG 0/1/2/3/4 in the two groups was 36/19/19/0 and 12/15/20/1 (p = 0.005), respectively. The requirements of total regression of positive lymph nodes were a primary tumor degenerated to TRG 3 with a size less than 6 mm in SCRT-delay (sensitivity, 60.9 %) or a primary tumor degenerated to TRG 2-4 with a size less than 5 mm at TRG 2 (sensitivity, 57.6 %) or 6 mm at TRG 3 and 4 (sensitivity, 84.2 %) in LC-CRT as indicated by the receiver operating characteristic curve analysis.

CONCLUSION

The tumor regression effect of LC-CRT on the primary tumor and positive nodes was more favorable than SCRT-delay, and LC-CRT is able to predict the LRG 3 response with a high sensitivity.

Diffusion-weighted magnetic resonance imaging for prediction of tumor response to neoadjuvant chemoradiotherapy using irinotecan plus S-1 for rectal cancer

The purpose of this study was to investigate the clinical value of diffusion-weighted (DW) magnetic resonance imaging (MRI) as a predictor of tumor response in patients receiving neoadjuvant chemoradiotherapy (NA-CRT) for rectal cancer (RC) through measurement of the apparent diffusion coefficient (ADC) value in each tumor. Neoadjuvant radiotherapy with a total dose of 45 Gy in 25 fractions was performed in all 16 patients with RC, combined with irinotecan and S-1. MRI was performed before and after NA-CRT. Multiple factors were assessed to predict the pathological response to NA-CRT. The pathological response rate was determined in 9 patients (56.3%). Statistical analyses indicated that the ADC value prior to NA-CRT was significantly lower in patients with a better response to NA-CRT (P=0.023). A cut-off value of 0.750×10^-3 mm²/sec obtained by a receiver operating characteristic curve analysis indicated a sensitivity of 77.8% and specificity of 85.7% for pathological responders to NA-CRT. In addition, the patients with lower ADC values exhibited a greater pathological response to NA-CRT (P=0.041). In conclusion, the ADC value of MRI of RC patients treated with NA-CRT followed by surgery may provide valuable information to predict the response to NA-CRT.