A comparison of formalin and GEWF in fixation of colorectal carcinoma specimens: rates of lymph node retrieval and effect on TNM staging

Lymph node stain after radical resection of rectal cancer mainly increased the harvest of mini lymph node: A randomized controlled trial

AIM

The lymph node status plays an important role in rectal cancer, which depends on adequate lymph node harvest. Lymph node stain techniques increase the lymph node harvest. The aim of this prospective study is to investigate which subgroups of lymph nodes harvested were increased mostly.

METHODS

From May 2020 to May 2022, 172 stage II-III rectal cancer patients were randomized to methylene blue (MB) stained group or unstained group to retrieve the lymph nodes. Methylene blue solution was injected into the inferior mesenteric artery, we dissected lymph nodes by palpation and sight. The lymph nodes were divided into 3 groups depending on the anatomy (main lymph nodes, superior rectal and perirectal lymph nodes (SPLNs), and pericolic lymph nodes located beyond 10 cm proximal to the tumor), and 3 groups depending on the short diameter of the nodes (big: ≥ 5 mm, small: 5-2 mm, mini: ≤ 2 mm).

RESULTS

The number of lymph nodes harvested with MB was significantly higher (22.0 (14.8, 32.0) vs 14.5 (11.0, 22.0); p < 0.001) without difference in positive patients or number of positive nodes. The positive rate of the big node was 3.5%, the small node was 1.9%, and the mini node was 0.2%. In the subgroup analysis, the median number of mini lymph nodes in the MB-stained group was significantly more than that of the unstained group (median (IQR): 9.0 (6.0, 14.0) vs 4.0 (2.0,6.0), p < 0.001); and the median number of SPLNs in the MB-stained group were significantly more than that of the unstained group (median (IQR): 15.0 (9.0, 19.0) vs 10.0 (6.0, 13.3), p < 0.001); these differences were existing in both patients with and without neoadjuvant treatments.

CONCLUSION

Intra-arterial injection of MB can significantly increase the number of lymph nodes harvested in rectal cancers, especially those mini lymph nodes. However, methylene blue staining did not significantly increase the number of positive lymph nodes and the proportion of patients with more than 12 lymph nodes, or affect lymph node staging accuracy after radical resection of rectal cancer.

CARNOY'S SOLUTION INCREASES LYMPH NODES COUNT IN COLON CANCER SPECIMENS WHEN COMPARED TO FORMALIN FIXATION: A RANDOMIZED TRIAL

AIM

At least 12 lymph nodes (LNs) should be examined following surgical resection of colon cancer. As it is difficult to find small LNs, fat clearing fixatives have been proposed, but there is no consensus about the best option. The objective of this study was to verify if Carnoy's solution (CS) increases the LN count in left colon cancer specimens.

METHODS

A prospective randomized trial (clinicaltrials.gov registration: NCT02629315) with 60 patients with left colon adenocarcinoma who underwent rectosigmoidectomy. Specimens were randomized for fixation with CS or 10% neutral buffered formalin (NBF). After dissection, the pericolic fat from the NBF group was immersed in CS and re-dissected (Revision). The primary endpoint was the total number of LNs retrieved.

RESULTS

Mean LN count was 36.6 and 26.8 for CS and NBF groups, respectively (p=0.004). The number of cases with <12 LNs was 0 (CS) and 3 (NBF, p=0.237). The duration of dissection was similar. LNs were retrieved in all cases during the revision (mean: 19, range: 4-37), accounting for nearly 40% of the LNs of this arm of the study. After the revision, no case was found in the NBF arm with <12 LNs. Two patients had metastatic LNs during the revision (no upstaging occurred).

CONCLUSION

Compared to NBF, CS increases LN count in colon cancer specimens. After conventional pathologic analysis, fixing the pericolic fat with CS and performing a second dissection substantially increased the number of LNs.

Comparative effectiveness of pathologic techniques to improve lymph node yield from colorectal cancer specimens. A systematic review and network meta-analysis

BACKGROUND

A number of randomized controlled trials (RCT) have compared different techniques to improve lymph node yield (LNY) in colorectal cancer specimens but data on comparative effectiveness are sparse. Our aim was to compare the relative effectiveness and rank all available techniques.

METHODS

A systematic search of Embase, Cochrane, PubMed and Scopus was performed for randomized trials. Pairwise meta-analysis performed if more than two homogeneous studies were available for each comparison. Network meta-analysis was used to rank and compare all available techniques.

RESULTS

Fifteen studies fulfilled the inclusion criteria. Techniques that were compared included methylene blue (MB), GEWF, Carnoy solution (CS), patent blue (PB), formalin, fat clearing (FC) and their combinations. The overall quality of studies was found to be fair. In pairwise meta-analysis MB had a higher lymph node yield weighted mean difference [WMD] 13.67 [4.83-22.51], P<0.01, lower number of specimens with less than 12 lymph nodes log Odds Ratio= -1.88(-2.8, -0.91), P<0.01 and higher LNY in patients with prior chemoradiotherapy (WMD 9.11 [3.15,15.08], p=0.02) as compared to formalin. Evaluation of the network plot revealed a well-connected network. In network meta-analysis MBFC had a higher LNY with [Mean Difference (MD) 13 and 95% credible interval (CI) (2.09- 23.91)] as compared to formalin. MBFC probability of being the best technique for LNY was 91.4%. In network meta-analysis MB did not have a statistically significant difference when compared to formalin.

CONCLUSIONS

MBFCS seems to be the most effective technique for LNY. Further studies are required to make safe conclusions for outcomes such positive lymph nodes and upstaging.

Carnoy solution versus GEWF solution for lymph node revealing in colorectal cancer: a randomized controlled trial

PURPOSE

This study aimed to compare the performance of two lymph node revealing solutions.

METHODS

This randomized clinical trial (NTC02704988) investigated patients with colon or rectal cancer who underwent surgical resection with D2 lymphadenectomy. Specimens submitted for conventional pathological examination were randomly assigned for additional fixation with Carnoy or GEWF solution, and dissection was performed to examine the missed lymph nodes. The number of lymph nodes retrieved, additional identified metastatic lymph nodes, lymph node upstaging, and complementary indication of adjuvant therapy were investigated.

RESULTS

The number of lymph nodes retrieved was significantly higher with the use of lymph node revealing solutions than with the conventional method in colon cancer (GEWF: 29.5 vs 27; p < 0.001; Carnoy: 27.7 vs 25.2; p < 0.001) and rectal cancer (GEWF: 25.8 vs 23.6; p < 0.001; Carnoy: 23.1 vs 20.8; p < 0.001). There were no differences between the solutions and conventional examination with respect to the median number of additional metastatic lymph nodes identified (0 in all arms), the number of patients with lymph node upstaging (colon cancer: 1 in the Carnoy arm, 0 in the GEWF arm; rectal cancer: 1 in the GEWF arm, 0 in the Carnoy arm), or the number of patients with complementary indication of adjuvant therapy (colon cancer: 1 in the Carnoy arm, 0 in the GEWF arm; rectal cancer: 0 in both arms).

CONCLUSION

Despite the higher number of lymph nodes retrieved, neither solution resulted in significant changes in patient staging or treatment. Both solutions exhibited equal performance with respect to all outcomes.

TRIAL REGISTRATION

NTC02704988.

Preoperative endoscopic tattooing technique improved lymph node retrieval in rectal cancer patients receiving neoadjuvant concurrent chemoradiotherapy

Aims

To describe the clinical utility of lymph node retrieval and prognostic value of tattooing in rectal cancer (RC) patients undergoing neoadjuvant concurrent chemoradiotherapy (CCRT).

Methods

A total 97 RC patients underwent preoperative CCRT, and 38 patients had preoperative endoscopic tattooing. Surgical intervention was performed after CCRT and the specimens were sampled as standard protocol in all patients. Other clinicopathological parameters correlated with lymph node retrieval status were also analysed.

Results

Fifteen patients (39.5%) of 38 RC patients in the tattooing group (TG) had adequate lymph node retrieval (>12) compared with 12 (20.3%) of 59 in the non-tattooing group. Higher lymph node retrieval rate was noted in the TG (p=0.04). In multivariable analysis, it showed tattooing was an independent predictive factor for higher lymph node retrieval in RC patients after CCRT (p=0.024) by logistic regression modelling. Besides histological grade, positive lymphovascular invasion, presence of lymph node metastasis, poor CCRT response and advanced pathological stage, inadequate lymph node retrieval was significantly associated with poor survival (all p<0.05) by Kaplan-Meier analysis. In multivariable analyses, the results revealed that lymph node retrieval (p=0.005), pathological stage (p=0.001) and tumour progression grade (p=0.02) were independent prognostic markers in RC patients receiving CCRT.

Conclusion

Preoperative endoscopic tattooing is a useful technique for RC patient receiving neoadjuvant CCRT. It can improve lymph node retrieval and provide an adequate diagnosis for proper treatment and prognosis.

Fat clearance of upper gastrointestinal resection specimens increases lymph node yield and may result in nodal upstaging

INTRODUCTION

Lymph node retrieval and quantification is an important element in staging upper gastrointestinal cancers. Our department introduced fat clearance for oesophagectomy and gastrectomy specimens in 2014. This study assessed the impact of this change on lymph node yield and upstaging.

METHODS

We reviewed histopathology data for upper gastrointestinal resection specimens. Patient demographics, clinical, macroscopic and microscopic data were compared with a historical cohort who did not undergo fat clearance.

RESULTS

Of 158 patients, 133 resection specimens received fat clearance resulting in a significantly higher lymph node yield than the historical cohort (22 vs 13 lymph nodes, p<0.0001). Fat clearance found additional positive nodes in 24.1% of patients and increased the number of cases achieving a minimum node yield of 15. Nodes found by fat clearance caused upstaging in 15% of the cohort.

DISCUSSION

Fat clearance increases node yield in upper gastrointestinal resection specimens and may cause nodal upstaging.