Does reevaluation of colorectal cancers with inadequate nodal yield lead to stage migration or the identification of metastatic lymph nodes?

A Modified Tumor-Node-Metastasis Classification for Primary Operable Colorectal Cancer

Background

The American Joint Committee on Cancer (AJCC) 8th tumor-node-metastasis (TNM) classification for colorectal cancer (CRC) has limited ability to predict prognosis.

Methods

We included 45 379 eligible stage I-III CRC patients from the Surveillance, Epidemiology, and End Results Program. Patients were randomly assigned individually to a training (n = 31 772) or an internal validation cohort (n = 13 607). External validation was performed in 10 902 additional patients. Patients were divided according to T and N stage permutations. Survival analyses were conducted by a Cox proportional hazard model and Kaplan-Meier analysis, with T1N0 as the reference. Area under receiver operating characteristic curve and Akaike information criteria were applied for prognostic discrimination and model fitting, respectively. Clinical benefits were further assessed by decision curve analyses.

Results

We created a modified TNM (mTNM) classification: stages I (T1-2N0-1a); IIA (T1N1b, T2N1b, T3N0); IIB (T1-2N2a-2b, T3N1a-1b, T4aN0); IIC (T3N2a, T4aN1a-2a, T4bN0); IIIA (T3N2b, T4bN1a); IIIB (T4aN2b, T4bN1b); and IIIC (T4bN2a-2b). In the internal validation cohort, compared with the AJCC 8th TNM classification, the mTNM classification showed superior prognostic discrimination (area under receiver operating characteristic curve = 0.675 vs 0.667, respectively; 2-sided P < .001) and better model fitting (Akaike information criteria = 70 937 vs 71 238, respectively). Similar findings were obtained in the external validation cohort. Decision curve analyses revealed that the mTNM had superior net benefits over the AJCC 8th TNM classification in the internal and external validation cohorts.

Conclusions

The mTNM classification provides better prognostic discrimination than AJCC 8th TNM classification, with good applicability in various populations and settings, to help better stratify stage I-III CRC patients into prognostic groups.

Fat clearance and conventional fixation identified ypN0 rectal cancers following intermediate neoadjuvant radiotherapy have similar long-term outcomes

BACKGROUND

As a prognostic factor for colorectal cancer, lymph node (LN) status, particularly the number of LN harvested, has been demonstrated to be essential in the evaluation of quality control in terms of surgical specimen. Neoadjuvant chemoradiation, however, decreases the LN harvest. Therefore, certain approaches (such as fat clearance or methylene blue) has drawn significant attention in order to raise LN yield.

AIM

To compare the long-term oncologic outcome of ypN0 rectal cancer identified using fat clearance (FC) or conventional fixation (CF) following 30 Gy in 10 fractions (30 Gy/10f) of neoadjuvant radiotherapy (nRT).

METHODS

Three hundred and eighty-two patients with resectable and locally advanced rectal cancer were treated by 30 Gy/10f intermediate nRT (biologically equivalent dose of 36 Gy) plus total mesorectal excision. Two specimen fixation methods (FC or CF) were non-randomly used. The ypN0 status was identified in 124 and 101 patients in the FL and CF groups, respectively. Primary endpoints were local recurrence-free survival (LRFS) and cancer-specific survival (CSS).

RESULTS

The median follow-up of patients was 5.1 years. The median numbers of retrieved LNs in the FC and CF groups were 19.5 (range, 4-47) and 12 (range, 0-44), respectively, with a significant difference (P = 0.000). The percentages of patients with 12 or more retrieved nodes were 82.3% and 50.5% (101/159) in the FC and CF groups, respectively, with a significant difference (P = 0.000). The LRFS at 5 years were 95.7% and 94.6% in the FC and CF groups, respectively, without statistical difference (P = 0.819). The CSS at 5 years were 92.0% and 87.2% in the FC and CF groups, respectively, without statistical difference (P = 0.482).

CONCLUSION

For patients with ypN0 rectal cancer who underwent 30 Gy/10f preoperative radiotherapy, the increased retrieval of LNs using fat clearance is not associated with survival benefit. This time-consuming fixation method has a low efficacy as a routine practice.

Effect of Responsiveness of Lymph Nodes to Preoperative Chemoradiotherapy in Patients With Rectal Cancer on Prognosis After Radical Resection

BACKGROUND

The influence of lymph node (LN) response to preoperative chemoradiotherapy (PCRT) has not been well evaluated for prognosis and additional use of adjuvant treatment after PCRT in rectal cancer patients. The aim of this study was to evaluate the prognostic effect of LN regression grade (LRG) in rectal cancer after PCRT and radical resection.

PATIENTS AND METHODS

From 2008 to 2011, 389 patients with rectal cancer treated with PCRT followed by radical resection were identified. The pathologic LRG (pLRG) score was determined on the basis of the proportion of tumor cells and fibrosis. The sum of the pLRG of each evaluated LN was used as the final LRG score, LRG-sum. Cox regression analysis was used to evaluate the association of LRG-sum and recurrence-free survival (RFS).

RESULTS

The distribution of LRG-sum was significantly associated with tumor regression grade of the primary tumor (P < .001). LRG-sum showed different values even in patients with the same number of metastatic LNs. LRG-sum was confirmed as the most relevant associated factor among LN-related variables with RFS along with ypT stage in multivariate analysis. Patients were categorized according to the cutoff points of LRG-sum distribution: LRG1 (LRG-sum 0 to ≤3), LRG2 (LRG-sum 3 to ≤21), and LRG3 (LRG-sum >21). RFS showed a significant difference according to LRG group (P < .001) and showed more effective difference in RFS in the same ypN stage subgroup on the basis of the number of metastatic LNs.

CONCLUSION

LRG was a prognostic factor of oncologic outcomes of rectal cancer. LN response to PCRT might help in prognostication and determination of treatments after PCRT.

A Nomogram to Predict Adequate Lymph Node Recovery before Resection of Colorectal Cancer

Increased lymph node count (LNC) has been associated with prolonged survival in colorectal cancer (CRC), but the underlying mechanisms are still poorly understood. The study aims to identify new predictors and develop a preoperative nomogram for predicting the probability of adequate LNC (≥ 12). 501 eligible patients were retrospectively selected to identify clinical-pathological factors associated with LNC ≥ 12 through univariate and multivariate logistic regression analyses. The nomogram was built according to multivariate analyses of preoperative factors. Model performance was assessed with concordance index (c-index) and area under the receiver operating characteristic curve (AUC), followed by internal validation and calibration using 1000-resample bootstrapping. Clinical validity of the nomogram and LNC impact on stage migration were also evaluated. Multivariate analyses showed patient age, CA19-9, circulating lymphocytes, neutrophils, platelets, tumor diameter, histology and deposit significantly correlated with LNC (P < 0.05). The effects were marginal for CEA, anemia and CRC location (0.05 < P < 0.1). The multivariate analyses of preoperative factors suggested decreased age, CEA, CA19-9, neutrophils, proximal location, and increased platelets and diameter were significantly associated with increased probability of LNC ≥ 12 (P < 0.05). The nomogram achieved c-indexes of 0.75 and 0.73 before and after correction for overfitting. The AUC was 0.75 (95% CI, 0.70–0.79) and the clinically valid threshold probabilities were between 10% and 60% for the nomogram to predict LNC < 12. Additionally, increased probability of adequate LNC before surgery was associated with increased LNC and negative lymph nodes rather than increased positive lymph nodes, lymph node ratio, pN stages or AJCC stages. Collectively, the results indicate the LNC is multifactorial and irrelevant to stage migration. The significant correlations with preoperative circulating markers may provide new explanations for LNC-related survival advantage which is reflected by the implication of regional and systemic antitumor immune responses.

Lymph Node Yield in Colon Cancer: Individuals Can Make the Difference

AIM

To investigate the influence of individual surgeons and pathologists on examining an adequate (i.e. ≥10) number of lymph nodes in colon cancer resection specimens.

PATIENTS AND METHODS

The number of lymph nodes was evaluated in surgically treated patients for colon cancer at our hospital from 2008 through 2010, excluding patients who had received neo-adjuvant treatment. The patient group consisted of 156 patients with a median age of 73 (interquartile range (IQR) 63-82 years) and a median of 12 lymph nodes per patient (IQR 8-15). In 106 patients (67.9%), 10 or more nodes were histopathologically examined.

RESULTS

At univariate analysis, the examination of ≥10 nodes was influenced by tumour size (p = 0.05), tumour location (p = 0.015), type of resection (p = 0.034), individual surgeon (p = 0.023), and pathologist (p = 0.005). Neither individual surgeons nor pathologists did statistically and significantly influence the chance of finding an N+ status. Age (p = 0.044), type of resection (p = 0.007), individual surgeon (p = 0.012) and pathologist (p = 0.004) were independent prognostic factors in a multivariate model for finding ≥10 nodes.

CONCLUSION

Though cancer staging was not affected in this study, individual efforts by surgeons and pathologists play a critical role in achieving optimal lymph node yield through conventional methods.