Determinants of lymph node count and positivity in patients undergoing surgery for colon cancer

Preoperative Predictors of Lymph Node Metastasis in Colon Cancer

Background

Lymph node metastasis (LNM) is a well-established prognostic factor for colon cancer. Preoperative LNM evaluation is relevant for planning colon cancer treatment. The aim of this study was to construct and evaluate a nomogram for predicting LNM in primary colon cancer according to pathological features.

Patients and Methods

Six-hundred patients with clinicopathologically confirmed colon cancer (481 cases in the training set and 119 cases in the validation set) were enrolled in the Affiliated Cancer Hospital of Guangxi Medical University from January 2010 to December 2019. The expression of molecular markers (p53 and β-catenin) was determined by immunohistochemistry. Multivariate logistic regression was used to screen out independent risk factors, and a nomogram was established. The accuracy and discriminability of the nomogram were evaluated by consistency index and calibration curve.

Results

Univariate logistic analysis revealed that LNM in colon cancer is significantly correlated (P <0.05) with tumor size, grading, stage, preoperative carcinoembryonic antigen (CEA) level, and peripheral nerve infiltration (PNI). Multivariate logistic regression analysis confirmed that CEA, grading, and PNI were independent prognostic factors of LNM (P <0.05). The nomogram for predicting LNM risk showed acceptable consistency and calibration capability in the training and validation sets.

Conclusions

Preoperative CEA level, grading, and PNI were independent risk factor for LNM. Based on the present parameters, the constructed prediction model of LNM has potential application value.

Novel Model to Predict the Prognosis of Patients with Stage II-III Colon Cancer

Different opinions exist on the relationship between the C-reactive protein-to-albumin ratio (CAR) and the prognosis of colon cancer. This study is aimed at evaluating the relationship between CAR and prognosis of stage II–III colon cancer and establishing a clinical prognosis model. Patients were randomised to a training set (566 cases) and validation set (110 cases). The relationship between CAR and clinicopathological variables was calculated, and the Kaplan-Meier method was used to analyse the overall survival (OS) rate of colon cancer. In the training set, colon cancer independent risk factors were included in the prognosis model and then tested in the validation set. The accuracy and discrimination of the model were assessed using the C-index and calibration curves. Compared with patients with low CAR, patients with high CAR showed significantly poorer survival (P = 0.020). In the multivariate analysis, CAR, carcinoembryonic antigen (CEA), lymph node metastasis, operation mode, and perineural invasion were identified as independent prognostic indicators and adopted to establish the prediction model. The C-index of the nomogram for predicting OS reached 0.751 in the training set and 0.719 in the validation set. The calibration curve exhibited good consistency. In the present study, the CAR may be an independent prognostic factor for stage II–III colon cancer, and the nomogram has a certain predictive value. However, further prospective large-sample research needs to be conducted to validate our findings.

Colon cancer-specific diagnostic and prognostic biomarkers based on genome-wide abnormal DNA methylation

Abnormal DNA methylation is a major early contributor to colon cancer (COAD) development. We conducted a cohort-based systematic investigation of genome-wide DNA methylation using 299 COAD and 38 normal tissue samples from TCGA. Through conditional screening and machine learning with a training cohort, we identified one hypomethylated and nine hypermethylated differentially methylated CpG sites as potential diagnostic biomarkers, and used them to construct a COAD-specific diagnostic model. Unlike previous models, our model precisely distinguished COAD from nine other cancer types (e.g., breast cancer and liver cancer; error rate ≤ 0.05) and from normal tissues in the training cohort (AUC = 1). The diagnostic model was verified using a validation cohort from The Cancer Genome Atlas (AUC = 1) and five independent cohorts from the Gene Expression Omnibus (AUC ≥ 0.951). Using Cox regression analyses, we established a prognostic model based on six CpG sites in the training cohort, and verified the model in the validation cohort. The prognostic model sensitively predicted patients’ survival (p ≤ 0.00011, AUC ≥ 0.792) independently of important clinicopathological characteristics of COAD (e.g., gender and age). Thus, our DNA methylation analysis provided precise biomarkers and models for the early diagnosis and prognostic evaluation of COAD.

The quality of lymph node harvests in extralevator abdominoperineal excisions

Background

Lymph node (LN) harvest in colorectal cancer resections is a well-recognised prognostic factor for disease staging and determining survival, particularly for node-negative (N0) diseases. Extralevator abdominoperineal excisions (ELAPE) aim to prevent “waisting” that occurs during conventional abdominoperineal resections (APR) for low rectal cancers, and reducing circumferential resection margin (CRM) infiltration rate. Our study investigates whether ELAPE may also improve the quality of LN harvests, addressing gaps in the literature.

Methods

This retrospective observational study reviewed 2 sets of 30 consecutive APRs before and after the adoption of ELAPE in our unit. The primary outcomes are the total LN counts and rates of meeting the standard of 12-minimum, particularly for those with node-negative disease. The secondary outcomes are the CRM involvement rates. Baseline characteristics including age, sex, laparoscopic or open surgery and the use of neoadjuvant chemoradiotherapy were accounted for in our analyses.

Results

Median LN counts were slightly higher in the ELAPE group (16.5 vs. 15). Specimens failing the minimum 12-LN requirements were almost significantly fewer in the ELAPE group (OR 0.456, P = 0.085). Among node-negative rectal cancers, significantly fewer resections failed the 12-LN standard in the ELAPE group than APR group (OR 0.211, P = 0.044). ELAPE led to a near-significant decrease in CRM involvement (OR 0.365, P = 0.088). These improvements were persistently observed after taking into account baselines and potential confounders in regression analyses.

Conclusion

ELAPE provides higher quality of LN harvests that meet the 12-minimal requirements than conventional APR, particularly in node-negative rectal cancers. The superiority is independent of potential confounding factors, and may implicate better clinical outcomes.

Tumor sidedness influences prognostic impact of lymph node metastasis in colon cancer patients undergoing curative surgery

This study aimed to evaluate prognostic impacts of the number of lymph nodes (LNs) examined and LN ratio on cancer-specific mortality after surgery in patients with right-sided colon cancer (RCC) or left-sided colon cancer (LCC) using the Surveillance, Epidemiology, and End Results database. Number of LNs examined and LN ratio were treated as categorical and/or continuous. Competing risks proportional hazards regressions adjusted by propensity score were performed. All included patients had stage I, II, or III disease, and 45.1% of them had RCC. RCC and LCC patients with high level of LNs examined had better prognosis after segmental resection or hemicolectomy. RCC and LCC patients with higher LN ratio had worse prognosis regardless of surgery. Survival benefit of having high level of LNs examined was observed in RCC patients with stage I, II, or III disease, but only in LCC patients with stage II disease. Both higher LN ratio and high level of LN were negative prognostic factors for cancer-specific mortality in stage III patients regardless of tumor sidedness. In conclusion, RCC patients in various conditions had worse or comparable prognosis compared to their LCC counterparts, which reflected the severity of LN metastasis.

Prognostic impact of examined lymph node count in pT1N0M0 esophageal cancer: A population-based study

Background

Research on the impact of examined lymph node (ELN) count on node‐negative esophageal cancer (EC) especially pT1N0M0 EC is inadequate. This study was designed to analyze the prognostic impact of ELN count on pT1N0M0 EC.

Methods

Data of resected pT1N0M0 EC patients between 1988 and 2015 were extracted from the United States Surveillance, Epidemiology, and End Results (SEER) database. The association between ELN count and overall survival (OS) or esophageal cancer‐specific survival (ECSS) were investigated. Factors that may predict the outcome were identified using the Kaplan‐Meier method and the Cox proportional‐hazards model.

Results

A total of 906 patients who underwent resection with at least one lymph node (LN) retrieved met our criteria. The cumulative 5‐year OS was 67.6%, while the cumulative 5‐year ECSS was 75.4%. X‐Tile analysis showed that 12 was the optimal cutoff value for ELN count in terms of both OS (χ2 = 28.764, P < 0.0001) and ECSS (χ2 = 15.668, P = 0.0026). A Kaplan‐Meier survival analysis and log‐rank comparison revealed that ELN > 12 was significantly associated with better OS (HR, 0.532; 95% CI, 0.421–0.672; P < 0.001) and ECSS (HR, 0.561; 95% CI, 0.420–0.749; P < 0.001) rates than ELN ≤12. The OS and ECSS benefit of increasing ELN count were also reflected in the multivariate analysis after adjustment for age, sex, race, marital status, location, T stage, tumor size, pathology, and differentiation.

Conclusions

These findings indicated that greater number of ELN count exhibits prognostic significance in pT1N0M0 EC. We recommend more than 12 LNs should be examined in pT1N0M0 EC.

Assessment of the external validity of the AJCC 8th staging system for small intestinal adenocarcinoma: a time to reconsider the role of tumor location?

Background

The current study evaluates the validity and performance of the 8^th edition of the American Joint Committee on Cancer (AJCC) staging system for small intestinal adenocarcinoma patients.

Methods

Surveillance, Epidemiology and End Results (SEER) database [2004-2015] was explored and AJCC 6^th, 7^th, and 8^th versions were assigned for each patient. Through Kaplan-Meier estimates, overall survival analyses were conducted. Cox regression analysis (adjusted for age, race, gender, sub-site, grade and surgical treatment) was conducted for cancer-specific survival and additionally, pairwise hazard ratio comparisons were performed.

Results

A total of 2,997 small intestinal adenocarcinoma patients were eligible and included in the analysis. Overall survival was compared according to the three AJCC staging systems. For the three versions, the P value for the trend in overall survival was significant (P<0.0001). Cancer-specific Cox regression hazard was calculated for the three staging systems. Pairwise hazard ratio comparisons between different AJCC 6^th stages were conducted and all P values for comparisons were significant (P<0.0001). Pairwise hazard ratio comparisons between different AJCC 7^th and 8^th stages were also performed, and all comparisons were significant (P<0.05) except for stage IIB vs. IIIA. C-statistic (using death from small intestinal adenocarcinoma as the dependent variable) for AJCC 6^th staging system was: 0.645 [standard error (SE): 0.011; 95% CI: 0.623-0.668]; for c-statistic for AJCC 7^th staging system was 0.658 (SE: 0.011; 95% CI: 0.637-0.680); while c-statistic for AJCC 8^th staging system was 0.660 (SE: 0.011; 95% CI: 0.638-0.682). Multivariate analysis of factors affecting cancer-specific survival suggested that older age (P=0.005), higher lymph node ratio (P<0.0001) and duodenal localization of the primary are associated with worse outcomes (P=0.008).

Conclusions

There is no evidence that AJCC 8^th system provided better prognostic characterization compared to previous AJCC staging systems for small intestinal adenocarcinoma. Subsite-specific staging paradigms should be explored in future editions of the staging system.

Defining the Role of Lymphadenectomy for Pancreatic Neuroendocrine Tumors: An Eight-Institution Study of 695 Patients from the US Neuroendocrine Tumor Study Group

BACKGROUND

Preoperative factors that reliably predict lymph node (LN) metastases in pancreatic neuroendocrine tumors (PanNETs) are unclear. The number of LNs needed to accurately stage PanNETs has not been defined.

METHODS

Patients who underwent curative-intent resection of non-functional PanNETs at eight institutions from 2000 to 2016 were analyzed. Preoperative factors associated with LN metastases were identified. A procedure-specific target for LN retrieval to accurately stage patients was determined.

RESULTS

Of 695 patients who underwent resection, 33% of tumors were proximal (head/uncinate) and 67% were distal (neck/body/tail). Twenty-six percent of patients (n = 158) had LN-positive disease, which was associated with a worse 5-year recurrence-free survival (RFS; 60% vs. 86%; p < 0.001). The increasing number of positive LNs was not associated with worse RFS. Preoperative factors associated with positive LNs included tumor size ≥ 2 cm (odds ratio [OR] 6.6; p < 0.001), proximal location (OR 2.5; p < 0.001), moderate versus well-differentiation (OR 2.1; p = 0.006), and Ki-67 ≥ 3% (OR 3.1; p < 0.001). LN metastases were also present in tumors without these risk factors: < 2 cm (9%), distal location (19%), well-differentiated (23%), and Ki-67 < 3% (16%). Median LN retrieval was 13 for pancreatoduodenectomy (PD), but only 9 for distal pancreatectomy (DP). Given that PD routinely includes a complete regional lymphadenectomy, a minimum number of LNs to accurately stage patients was not identified. However, for DP, removal of less than seven LNs failed to discriminate 5-year RFS between LN-positive and LN-negative patients (less than seven LNs: 72% vs. 83%, p = 0.198; seven or more LNs: 67% vs. 86%; p = 0.002).

CONCLUSIONS

Tumor size ≥ 2 cm, proximal location, moderate differentiation, and Ki-67 ≥ 3% are preoperative factors that predict LN positivity in resected non-functional PanNETs. Given the 9-23% incidence of LN metastases in patients without such risk factors, routine regional lymphadenectomy should be considered. PD inherently includes sufficient LN retrieval, while DP should aim to remove seven or more LNs for accurate staging.

A New Metastatic Lymph Node Classification-based Survival Predicting Model in Patients With Small Bowel Adenocarcinoma: A Derivation and Validation Study

BACKGROUND

Current methods of lymph node (LN) staging are controversial in predicting the survival of SBA. We aimed to develop an alternative LN-classification-based nomogram to individualize SBA prognosis.

METHODS

Based on the data from the Surveillance, Epidemiology, and End Results (SEER) database of patients diagnosed with SBA between 2004 and 2014, we identified the cut-off points for the number of LNs examined and the number found to be metastatic using the K-adaptive partitioning (KAPS) algorithm. Using metastatic LNs, a nomogram predicting the survival of SBA was derived, internally and externally validated, and measured by calibration curve, C-index, and decision curve analysis (DCA), and compared to the 8th TNM stage.

RESULTS

A total of 1516 patients were included. The cut-off of 17 was the optimal examined LN number. For metastatic LN numbers, the cut-off points were 0, 2, and 8. The C-index for the nomogram was higher than the 8th TNM staging (internal: 0.734; 95% CI, 0.693 to 0.775 vs. 0.677; 95% CI, 0.652 to 0.702, P < 0.001; external: 0.715; 95% CI, 0.674 to 0.756 vs. 0.648; 95% CI, 0.602 to 0.693, P < 0.001). Also, the nomogram showed good calibration in internal and external validation and larger net benefit than TNM staging.

CONCLUSION

We modified current N staging into a 4-level staging system based on the number of metastatic LNs: N0, no LN metastasis; N1, 1-2 metastatic LNs; N2, 3-8 metastatic LNs, and N3, >8 metastatic LNs and set the least examined LN number to 17. A nomogram based on this staging showed great clinical usability than TNM staging for predicting the survival of SBA patients.