A minimum yield of twelve lymph nodes in rectal cancer remains valid in the era of neo-adjuvant treatment : results from a national cohort study

Rectal Cancer: Are 12 Lymph Nodes the Limit?

Lymph node dissection is a crucial element of oncologic rectal surgery. Many guidelines regard the removal of at least 12 lymph nodes as the quality criterion in rectal cancer. However, this recommendation remains controversial. This study examines the factors influencing the lymph node yield and the validity of the 12-lymph node limit. Patients with rectal cancer who underwent low anterior resection or abdominoperineal amputation between 2000 and 2010 were analyzed. In total, 20,966 patients from 381 hospitals were included. Less than 12 lymph nodes were found in 20.53% of men and 19.31% of women (p = 0.03). The number of lymph nodes yielded increased significantly from 2000, 2005 and 2010 within the quality assurance program for all procedures. The univariate analysis indicated a significant (p < 0.001) correlation between lymph node yield and gender, age, pre-therapeutic T-stage, risk factors and neoadjuvant therapy. The multivariate analyses found T3 stage, female sex, the presence of at least one risk factor and neoadjuvant therapy to have a significant influence on yield. The probability of finding a positive lymph node was proportional to the number of examined nodes with no plateau. There is a proportional relationship between the number of examined lymph nodes and the probability of finding an infiltrated node. Optimal surgical technique and pathological evaluation of the specimen cannot be replaced by a numeric cut-off value.

Role of lymph node yield and lymph node ratio in predicting outcomes in non-metastatic colorectal cancer

Background

Lymph node yield (LNY) of 12 or more in resection of colorectal cancer is recommended in current international guidelines. Although a low LNY (less than 12) is associated with poorer outcome in some studies, its prognostic value is unclear in patients with early‐stage colorectal or rectal cancer with a complete pathological response following neoadjuvant therapy. Lymph node ratio (LNR), which reflects the proportion of positive to total nodes obtained, may be more accurate in predicting outcome in stage III colorectal cancer. This study aimed to identify factors correlating with LNY and evaluate the prognostic role of LNY and LNR in colorectal cancer.

Methods

An observational study was performed on patients with colorectal cancer treated at three hospitals in Melbourne, Australia, from January 2010 to March 2016. Association of LNY and LNR with clinical variables was analysed using linear regression. Disease‐free (DFS) and overall (OS) survival were investigated with Cox regression and Kaplan–Meier survival analyses.

Results

Some 1585 resections were analysed. Median follow‐up was 27·1 (range 0·1–71) months. Median LNY was 16 (range 0–86), and was lower for rectal cancers, decreased with increasing age, and increased with increasing stage. High LNY (12 or more) was associated with better DFS in colorectal cancer. Subgroup analysis indicated that low LNY was associated with poorer DFS and OS in stage III colonic cancer, but had no effect on DFS and OS in rectal cancer (stages I–III). Higher LNR was predictive of poorer DFS and OS.

Conclusion

Low LNY (less than 12) was predictive of poor DFS in stage III colonic cancer, but was not a factor for stage I or II colonic disease or any rectal cancer. LNR was a predictive factor in DFS and OS in stage III colonic cancer, but influenced DFS only in rectal cancer.

Lymph Node Yield After Neoadjuvant Chemoradiotherapy in Rectal Cancer Specimens: A Randomized Trial Comparing Two Fixatives

BACKGROUND

It is widely reported that neoadjuvant chemoradiation reduces lymph node yield in rectal cancer specimens. Some have questioned the adequacy of finding ≥12 lymph nodes for accurate staging, and fewer nodes were correlated with good response. Others reported that low lymph node count raises the chance for understaging and correlates with worse survival. In addition, a few studies demonstrated that diligent specimen analysis increases lymph node count.

OBJECTIVE

The aim of this study was to compare Carnoy's solution and formalin concerning lymph node yield in specimens of patients with rectal cancer after neoadjuvant chemoradiation.

DESIGN

This is a prospective randomized trial that was conducted from 2012 to 2015.

SETTINGS

This study was performed in a reference cancer center in Brazil.

PATIENTS

Patients who underwent low anterior resection with total mesorectal excision after neoadjuvant chemoradiation for rectal adenocarcinoma were included.

INTERVENTION

Rectosigmoid specimens were randomized for fixation with Carnoy's solution or formalin.

MAIN OUTCOME MEASURES

A total of 130 specimens were randomized. After dissection, the residual fat from the formalin group was immersed in Carnoy's solution in search for missed lymph nodes (Revision).

RESULTS

The Carnoy's solution group had superior lymph node count (24.0 vs 16.3, p < 0.01) and fewer cases with <12 lymph nodes (6 vs 22, p = 0.001). The Revision group found lymph nodes in all cases (mean, 11.1), retrieving metastatic lymph nodes in 6 patients. It reduced the formalin cases with <12 lymph nodes from 33.8% to 4.6% and upstaged 2 patients. Tumor response to neoadjuvant chemoradiotherapy was not associated with lymph node count.

LIMITATIONS

This was a unicentric study.

CONCLUSIONS

Compared with formalin, the Carnoy's solution increases lymph node count and reduces the cases with <12 lymph nodes. Harvested lymph nodes are missed following routine analysis and this is clinically relevant. Finding <12 lymph nodes is not a sign of good response to neoadjuvant chemoradiation (www.clinicaltrials.gov. Unique identifier: NCT02629315). See Video Abstract at http://links.lww.com/DCR/A694.

What Is the Minimum Number of Examined Lymph Nodes After Neoadjuvant Therapy in Rectal Cancer?

BACKGROUND

To date, no guidelines have standardized the number of examined lymph nodes (eLNs) after neoadjuvant treatment. This study investigated the minimum number of eLNs required for patients with rectal cancer (RC) who received neoadjuvant treatment.

MATERIAL AND METHODS

This study was based on data from the Surveillance, Epidemiology, and End Results (SEER)-Medicare-linked database. We included 2173 patients with RC who received neoadjuvant therapy. Restricted cubic spline was used to analyze the association between eLNs and lymph node metastasis (LNM).

RESULTS

The number of eLNs was an independent predictive factor for the presence of LNM (odds ratio 1.033; 95% confidence interval 1.020-1.046; P < 0.001). When the number of eLN ≤ 16, 10 and 11 eLNs had the highest rates of positive LNM. Analysis of the restricted cubic spline method found that when number of eLNs was < 10, the LNM rate increased rapidly, but this increase was not so obviously when there were > 10 eLNs.

CONCLUSIONS

Among RC patients who receive neoadjuvant therapy, the minimum number of eLNs may be 10 to ensure pathological quality.

Lower lymph node yield following neoadjuvant therapy for rectal cancer has no clinical significance

Background

Obtaining 12 lymph nodes following resection for rectal cancer is an important prognostic marker. However, patients who have received neoadjuvant therapy are known to have a lower lymph node yield. We conducted this study to determine the clinical significance of evaluating <12 versus ≥12 lymph nodes in individuals who underwent surgery following neoadjuvant therapy for rectal cancer.

Methods

A retrospective analysis of all patients who received neoadjuvant therapy for locally advanced rectal cancer between January 2008 and December 2014 followed by proctectomy was conducted.

Results

In total, 217 patients were treated for rectal cancer. Mean follow-up was 23.4 (interquartile range, 9-40.5) months. Sixty-three (29.0%) patients received neoadjuvant therapy. There was a statistically significant difference in the number of patients with <12 lymph node yield between those who received neoadjuvant therapy and those who did not (27.0% vs. 9.1%, P=0.001). Amongst the 63 patients who received neoadjuvant therapy, lymph node yield of ≥12 was not associated with a statistically significant difference in time to recurrence [hazard ratio (HR) 0.17; 95% confidence interval (CI), 0.01-2.01, P=0.160] or time to death (HR 1.07; 0.15-7.90, P=0.946). Kaplan-Meier curves also did not show any significant difference between those with <12 lymph nodes and those with ≥12 lymph nodes in terms of recurrence and death (P=0.203 and P=0.762 respectively).

Conclusions

Although neoadjuvant therapy reduces the lymph node yield during surgery for locally advanced rectal cancer, this has no significance on the overall survival of the patient.

Resected irradiated rectal cancers: Are twelve lymph nodes really necessary in the era of neoadjuvant therapy?

BACKGROUND

Our study aims to identify the minimum number of lymph nodes (LN) associated with improved survival in patients who underwent NRT for stage II-III rectal cancer.

METHODS

Adults with clinical stage II and III rectal adenocarcinoma in the National Cancer Data Base were stratified by NRT. Multivariable Cox regression modeling with restricted cubic splines was used to determine the minimum number of LNs associated with improved survival.

RESULTS

Of 38,363 patients, 76% received NRT. After adjustment, a LNY≥12 was associated with improved survival among patients receiving NRT (HR 0.79, p < 0.0001) and those without NRT (HR 0.88, p = 0.04). Among patients receiving NRT, factors independently associated with LNY≥12 were younger age, private insurance, low comorbidity score, a recent year of diagnosis, higher T stage and grade, APR resection, and academic institution.

CONCLUSIONS

A minimum LNY of 12 confers a survival benefit for rectal cancer patients regardless of receiving neoadjuvant radiation therapy.

NEOADJUVANT THERAPY AND SURGERY FOR RECTAL CANCER. Comparative study between partial and complete pathological response

BACKGROUND

The approach of locally advanced extra-peritoneal rectal adenocarcinoma implies a treatment with neoadjuvant chemoradiotherapy associated with total mesorectal excision surgery. However, the tumors respond variably to this neoadjuvant therapy, and the mechanisms for response are not completely understood.

OBJECTIVE

Evaluate the variables related to the complete tumor response and the outcomes of patients who underwent surgery, comparing those with partial tumor regression and those with total remission of rectal lesion, at the pathological examination.

METHODS

Retrospective analysis of medical records of 212 patients operated between 2000 and 2010, in which 182 (85.9%) obtained partial remission at neoadjuvant therapy (Group 1) and 30 (14.1%), total remission (Group 2).

RESULTS

No difference was found between the groups in relation to gender, ethnicity, age, tumor distance from the anal verge, occurrence of metastases and synchronous lesions on preoperative staging, dose of radiotherapy and performed surgery. In Group 2, was verified high rate of complete remission when the time to surgery after neoadjuvant therapy was equal or less than 8 weeks (P=0.027), and a tendency of lower levels of pretreatment carcinoembryonic antigen (P=0.067). In pathological analysis, the Group 1 presented in relation to Group 2, more affected lymph nodes (average 1.9 and 0.5 respectively; P=0.003), more angiolymphatic (19.2% and 3.3%; P=0.032) and perineural involvement (15.4% and 0%; P=0.017) and greater number of lymph nodes examined (16.3 and 13.6; P=0.023). In the late follow-up, Group 1 also had lower overall survival than Group 2 (94.1 months and 136.4 months respectively; P=0.02) and disease-free survival (85.5 months and 134.6 months; P=0.004). There was no statistical difference between Group 2 and Group 1 in local recurrence (15% and 3.4%, respectively) and distant metastasis (28% and 13.8%, respectively).

CONCLUSION

In this study, the only factor associated with complete remission of rectal adenocarcinoma was the time between neoadjuvant therapy and surgery. This group of patients had less affected lymph nodes, less angiolymphatic and perineural involvement, a longer overall and disease-free survival, but no significant statistical difference was observed in local recurrence and distant metastasis. Although the complete pathologic remission was associated with better prognosis, this not implied in the cure of the disease for all patients.

The prognostic value of lymph node ratio in a national cohort of rectal cancer patients

OBJECTIVE

To analyze the prognostic implications of the lymph node ratio (LNR) in curative resected rectal cancer.

SUMMARY BACKGROUND DATA

It has been proposed that the LNR has a high prognostic impact in colorectal cancer, but the lymph node ratio has not been evaluated exclusively for rectal cancer in a large national cohort study.

METHODS

All 6793 patients in Denmark diagnosed with stage I to III adenocarcinoma of the rectum, and so treated in the period from 2003 to 2011, were included in the analysis. The cohort was divided into two groups according to whether or not neo-adjuvant treatment had been given.

RESULTS

In a multivariate analysis the pN status, ypN status and lymph node yield were found to be independent prognostic factors for overall survival, irrespective of neo-adjuvant therapy. The LNR was also found to be a significant prognostic factor with a Hazard Ratio ranging from 1.154 (95% CI: 0.930-1.432) (LNR: 0.01-0.08) to 2.974 (95% CI: 2.452-3.606) (LNR > 0.5) in the group of patients who had surgery to begin with and from 1.381 (95% CI: 0.891-2.139) (LNR: 0.01-0.08) to 2.915 (95% CI: 2.244-3.787) (LNR > 0.5) in the group of patients who had neo-adjuvant treatment.

CONCLUSIONS

The LNR reflects the influence on survival from N-status and the lymph node yield and since LNR was shown to be a significant prognostic predictor for overall survival in patients with curatively resected stage III rectal cancer irrespective of neo-adjuvant therapy we recommend that the introduction of LNR should be considered for rectal cancer in a revised TNM classification.