Heterogeneous survival between stage IIA and stage IIIA colon cancer when different numbers of lymph nodes are harvested

Lymph node yield in the pathological staging of resected nonmetastatic colon cancer: The more the better?

INTRODUCTION

Guidelines recommend regional lymphadenectomy with a lymph node yield (LNY) of at least 12 lymph nodes (LN) for adequate colon cancer (CC) staging. LNY ≥22LN may improve survival, especially in right-sided CC [Lee et al., Surg Oncol, 27(3), 2018]. This multicentric retrospective cohort study evaluated the impact of LNY and tumor laterality on CC staging and survival.

MATERIALS AND METHODS

Patients with stage I-III CC that underwent surgery from 2012 to 2018 were grouped according to LNY: <22 and ≥ 22. Primary outcomes were LN positivity (N+ rate) and disease-free survival (DFS). Overall survival (OS) was the secondary outcome. Exploratory analyses were performed for laterality and stage.

RESULTS

We included 795 patients (417 < 22LN, 378 ≥ 22LN); 53% had left-sided CC and 29%/37%/38% had stage I/II/III tumors. There was no association between LNY ≥22LN and N+ rate after adjustment for grade, T stage, lymphovascular invasion (LVI) and perineural invasion; a trend for a higher N+ rate in left-sided CC was identified (interaction p = 0.033). With a median follow-up of 63.6 months for DFS and 73.2 months for OS, 254 patients (31.9%) relapsed and 207 (26.0%) died. In multivariate analysis adjusted for age, ASA score, laparoscopic approach, T/N stage, mucinous histology, LVI and adjuvant chemotherapy, LNY ≥22LN was significantly associated with both DFS (HR 0.75, p = 0.031) and OS (HR 0.71, p = 0.025). Restricted cubic spline analysis showed a more significant benefit for right-sided CC.

CONCLUSION

LNY ≥22LN was associated with longer DFS and OS in patients with operable CC, especially for right-sided CC.

Optimal examined lymph node count in node-negative colon cancer should be determined

Background: We aimed to investigate the association between optimal examined lymph node (ELNs) and overall survival to determine the optimal cutoff point. Methods: Cox models and locally weighted scatterplot smoothing were used to fit hazard ratios and explore an optimal cutoff point based on the Chow test. Results: Overall survival increased significantly with the corresponding increase in the number of ELNs after adjusting for covariates. In Chow's test, the optimal cutoff point for node-negative colon cancer was 15, which was validated in both cohorts after controlling for confounders (Surveillance, Epidemiology, and End Results database: hazard ratio: 0.701, p < 0.001; single-center: HR: 0.563, p = 0.031). Conclusions: We conservatively suggest that the optimal number of ELNs for prognostic stratification is 15 in node-negative colon cancer.

A Modified Tumor-Node-Metastasis Staging System for Colon Cancer Patients with Fewer than Twelve Lymph Nodes Examined

BACKGROUND

To construct a modified tumor-node-metastasis (TNM) staging system for stage I-III colon cancer patients with lymph nodes examined (LNE) < 12.

METHODS

The clinicopathological and survival data of 3870 stage I-III colon cancer patients with LNE < 12 from the Surveillance, Epidemiology, and End Results (SEER) database between 2010 and 2015 (development cohort) and 126 stage I-III patients with LNE < 12 from the Second Affiliated Hospital of Harbin Medical University between 2011 and 2015 (validation cohort) were identified. The optimal stratification of LNR for cancer-specific survival (CSS) was achieved using X-tile software. The predictive accuracy of the modified stage (mStage) was determined by the concordance index (C-index).

RESULTS

The modified N stage (mN stage) was built based on the LNR (mN0: LNR = 0, mN1: 0 < LNR < 0.4 or cancer nodule formation and mN2: 0.4 ≤ LNR ≤ 1). Preferable C-indices could be found for mStage compared with TNM stage in both development (0.750 vs 0.727) and validation cohorts (0.682 vs 0.646). Besides, patients with mStage A and B diseases could not benefit from adjuvant chemotherapy, while in patients with mStage C-F diseases, those receiving radical surgery plus adjuvant chemotherapy presented better CSS than those with radical surgery alone.

CONCLUSIONS

The mStage system could predict the prognosis of colon cancer patients with LNE < 12 accurately and showed superior predictive power compared with conventional TNM staging system. Moreover, adjuvant chemotherapy might play inequable roles in patients with different mStage diseases.

Lymph Node Ratio as a Prognostic Marker in Rectal Cancer Survival: A Systematic Review and Meta-Analysis

Introduction 

The lymph node ratio (LNR) is defined as the ratio of the number of positive lymph nodes to the total number of nodes retrieved. LNR has recently emerged as a prognostic factor in rectal cancer. The objective of our study was to pool eligible studies to elucidate the prognostic role of LNR on overall survival (OS) and disease-free survival (DFS) in rectal cancer patients using a meta-analysis.

Methods

A systematic database search was performed in MEDLINE and Embase for relevant studies that reported LNR in rectal cancer. Two authors independently screened the relevant articles for selection and data extraction. As a result, a list of such studies and references, published in English up to December 2019, was obtained, and a total of 4,486 node-positive patients in 18 studies were included in this meta-analysis. RevMan software 5.3 (Cochrane Collaboration, the Nordic Cochrane Centre, Copenhagen) was used for conducting all statistical analyses.

Results

A higher LNR was significantly correlated with worse OS [hazard ratio (HR): 2.60; 95% confidence interval (CI): 2.21-3.06; p≤.00001] and DFS (HR: 2.43; 95% CI: 2.11-2.80; p≤.00001) in node-positive rectal cancer patients. Besides, LNR is an independent predictive and prognostic marker of OS and DFS (HR: 2.52; 95% CI: 2.17-2.94; p≤.00001 with I²=0%; p=.32 and HR: 2.63; 95% CI: 2.17-3.18; p≤.00001 with I²=0%; p=.63 respectively, irrespective of lymph nodal harvest).

Conclusions

Our present study demonstrates that LNR is an independent predictor of survival in rectal cancer. LNR should be considered as a parameter in future oncological staging systems. Further well-designed randomized control trials to prospectively assess LNR as an independent predictor of rectal cancer survival are necessary before its application in daily practice.

Factors affecting the number of lymph nodes retrieved after colo-rectal cancer surgery: A prospective single-centre study

BACKGROUND

The number of harvested lymph nodes (LNs) in colorectal cancer surgery relates to oncologic radicality and accuracy of staging. In addition, it affects the choice of adjuvant therapy, as well as prognosis. The American Joint Committee on Cancer defines at least 12 LNs harvested as adequate in colorectal cancer resections. Despite the importance of the topic, even in high-volume colorectal centres the rate of adequacy never reaches 100%. The aim of this study was to identify factors that affect the number of harvested LNs in oncologic colorectal surgery.

MATERIALS AND METHODS

We prospectively collected all consecutive patients who underwent colorectal cancer resection from January 1st 2013 to December 31st 2017 at Emergency Surgery Unit St Orsola University Hospital of Bologna.

RESULTS

Six hundred and forty-three consecutive patients (382 elective, 261 emergency) met the study inclusion criteria. Emergency surgery and laparoscopic approach did not have a significant influence on the number of harvested LNs. The adequacy of lymphadenectomy was negatively affected by age >80 (OR 3.47, p < 0.001), ASA score ≥3 (OR 3.48, p < 0.001), Hartmann's or rectal resection (OR 3.6, p < 0.001) and R1-R2 resection margins (OR 3.9, p = 0.006), while it was positively affected by T-status ≥3 (OR 0.33 p < 0.001).

CONCLUSION

Both the surgical technique and procedure regimen did not affect the number of lymphnodes retrieved. Age >80 and ASA score ≥3 and Hartmann's procedure or rectal resection showed to be risk factors related to inadequate lymphadenectomy in colorectal cancer surgery.

Metastatic Lymph Node Ratio (mLNR) is a Useful Parameter in the Prognosis of Colorectal Cancer; A Meta-Analysis for the Prognostic Role of mLNR

Background and objectives: The presenting study aimed to elucidate the prognostic role of the metastatic lymph node ratio (mLNR) in patients with colorectal cancer (CRC), using a meta-analysis. Materials and Methods: Using data from 90,274 patients from 14 eligible studies, we performed a meta-analysis for the correlation between mLNR and survival rate. Besides, subgroup analyses were performed, based on tumor stage, tumor location, and mLNR. Results: A high mLNR showed significant correlation with worse overall survival and disease-free survival rates in CRC patients (hazard ratio (HR), 1.617, 95% confidence interval (CI) 1.393-1.877, and HR 2.345, 95% CI 1.879-2.926, respectively). In patients with stage III, who had regional LN metastasis, the HRs were 1.730 (95% CI 1.266-2.362) and 2.451 (95% CI 1.719-3.494) for overall and disease-free survival, respectively. According to tumor location, rectal cancer showed a worse survival rate when compared to colon cancer. In the analysis for overall survival, when mLNR was 0.2, HR was the highest across the different subgroups (HR 5.040, 95% CI 1.780-14.270). However, in the analysis for disease-free survival, the subgroup with an mLNR < 0.2 had a higher HR than the other subgroups (HR 2.878, 95% CI 1.401-5.912). Conclusions: The mLNR may be a useful prognostic factor for patients with CRC, regardless of the tumor stage or tumor location. Further studies are necessary for the detailed criteria of mLNR before its application in daily practice.