Enzymatic Fat Dissolution Improves Detection of Small Lymph Nodes in Colon Cancer Surgery

Background Accurate lymph node evaluation is essential for staging colon cancer and guiding postoperative treatment decisions. In this study, we compared the efficacy of a simple enzymatic fat dissolution method with the conventional method for lymph node sampling from specimens after colon cancer surgery. Methods We enrolled 58 patients who underwent elective laparoscopic surgery for colon adenocarcinoma between May 2018 and May 2021 at Fukuoka University Hospital in Fukuoka, Japan. The specimens from these patients were treated using fat dissolution and were compared with specimens from 58 patients for which conventional manual palpation was used. Results A significantly greater number of lymph nodes were detected by the fat dissolution method compared with the conventional method (average per patient, 27.5 vs. 22.6, P = 0.02). In particular, the between-group difference was significant for lymph nodes measuring <5 mm (average per patient, 26.1 vs. 20.9; P = 0.01). Multivariate analysis showed that, compared with the conventional method, the fat dissolution method was significantly associated with the identification of lymph node metastasis. The positive rate of lymph nodes ≥10 mm in diameter was markedly higher along the inferior mesenteric artery than the ileocolic artery (100% vs. 52.6%). Conclusions The use of the fat dissolution method led to an increase in the number of small lymph nodes detected. Rates of metastasis according to lymph node size may depend on the lymph node station.

Optimal bowel resection margin in colon cancer surgery: prospective multicentre cohort study with lymph node and feeding artery mapping

Background

There are no standardised criteria for the 'regional' pericolic node in colon cancer, which represents a major cause of the international uncertainty regarding the optimal bowel resection margin. This study aimed to determine 'regional' pericolic nodes based on prospective lymph node (LN) mapping.

Methods

According to preplanned in vivo measurements of the bowel, the anatomical distributions of the feeding artery and LNs were determined in 2996 stages I-III colon cancer patients who underwent colectomy with resection margin >10 cm at 25 institutions in Japan.

Findings

The mean number of retrieved pericolic nodes was 20.9 (standard deviation, 10.8) per patient. In all patients except seven (0.2%), the primary feeding artery was distributed within 10 cm of the primary tumour. The metastatic pericolic node most distant from the primary tumour was within 3 cm in 837 patients, 3-5 cm in 130 patients, 5-7 cm in 39 patients and 7-10 cm in 34 patients. Only four patients (0.1%) had pericolic lymphatic spread beyond 10 cm; all of whom had T3/4 tumours accompanying extensive mesenteric lymphatic spread. The location of metastatic pericolic node did not differ by the feeding artery's distribution. Postoperatively, none of the 2996 patients developed recurrence in the remaining pericolic nodes.

Interpretation

The pericolic nodes designated as 'regional' were those located within 10 cm of the primary tumours, which should be fully considered when determining the bowel resection margin, even in the era of complete mesocolic excision.

Funding

Japanese Society for Cancer of the Colon and Rectum.

Prognostic Nomogram for Rectal Cancer Patients With Tumor Deposits

Aim

Tumor deposits (TDs) are an aggressive hallmark of rectal cancer, but their prognostic value has not been addressed in current staging systems. This study aimed to construct and validate a prognostic nomogram for rectal cancer patients with TDs.

Methods

A total of 1,388 stage III–IV rectal cancer patients who underwent radical surgical resection from the Surveillance, Epidemiology, and End Results (SEER) database were retrospectively analyzed to identify the clinical value of TDs. TD-positive rectal cancer patients in the SEER database were used as the training set to construct a prognostic model, which was validated by Fujian Cancer Hospital. Three models were constructed to predict the prognosis of rectal cancer patients with TDs, including the least absolute shrinkage and selection operator regression (LASSO, model 1), backward stepwise regression (BSR, model 2), and LASSO followed by BSR (model 3). A nomogram was established among the three models.

Results

In the entire cohort, TD was also identified as an independent risk factor for overall survival (OS), even after adjusting for baseline factors, stage, other risk factors, treatments, and all the included variables in this study (all P < 0.05). Among patients with TDs, model 3 exhibited a higher C-index and area under the curves (AUCs) at 3, 4, and 5 years compared with the American Joint Committee on Cancer staging system both in the training and validation sets (all P < 0.05). The nomogram obtained from model 3 showed good consistency based on the calibration curves and excellent clinical applicability by the decision curve analysis curves. In addition, patients were divided into two subgroups with apparently different OS according to the current nomogram (both P < 0.05), and only patients in the high-risk subgroup were found to benefit from postoperative radiotherapy (P < 0.05).

Conclusion

We identified a novel nomogram that could not only predict the prognosis of rectal cancer patients with TDs but also provide reliable evidence for clinical decision-making.

The Value of Sentinel Lymph Node Mapping for the Staging of Node-Negative Colon Cancer: Propensity Score and Mediation Analyses

Objectives

Mediation analysis to assess the protective impact of sentinel lymph node (SLN) mapping on prognosis and survival of patients with colon cancer through a more precise evaluation of the lymph node (LN) status.

Background

Up to 20% of patients with node-negative colon cancer develop disease recurrence. Conventional histopathological LN examination may be limited in describing the real metastatic burden of LN.

Methods

Data of 312 patients with stage I & II colon cancer was collected prospectively. Patients were either staged using intraoperative SLN mapping with multilevel sectioning and immunohistochemical staining of the SLN or conventional techniques. The value of the SLN mapping for the detection of truly node-negative patients was assessed using Cox regression and mediation analysis.

Results

SLN mapping was performed in 143 patients. Disease recurrence was observed in 13 (9.1%) patients staged with SLN mapping and in 27 (16%) staged conventionally. Five-year overall survival (OS) rate was 82.7% (95% confidence interval [CI], 76.5-89.4%) with SLN mapping compared with 65.8% (95% CI, 58.8-73.7%). Five-year cancer-specific survival (CSS) was 95.1% (95% CI, 91.3-99.0%) with SLN mapping compared with 92.5% (95% CI, 88.0-97.2%). Node-negative staging with SLN mapping was associated with significantly better OS (hazard ratio [HR], 0.64; 95% CI, 0.56-0.72; P < 0.001) and CSS (HR, 0.49; 95% CI, 0.39-0.61; P < 0.001) in multivariate analysis. Mediation analysis confirmed a direct protective effect of SLN mapping on OS (HR, 0.78; 95% CI, 0.52-0.96; P < 0.01) and disease-free survival (DFS) (HR, 0.75; 95% CI, 0.48-0.89; P < 0.01).

Conclusions

Staging performed by SLN mapping with multilevel sectioning provides more accurate results than conventional staging. The observed clinically relevant and statistically significant benefit in OS and DFS is explained by a more accurate detection of positive LN by SLN mapping.

Penicillin disrupts mitochondrial function and induces autophagy in colorectal cancer cell lines

Colorectal cancer is a common malignant tumor of the gastrointestinal tract. Currently, the main treatment is surgical resection, which can be combined with other treatments. However, treatment efficacy is poor, and colorectal cancer is prone to relapse and metastasis; thus, identifying an effective anti-cancer drug is an urgent requirement. The present study examined the antagonistic effect of penicillin on cultured colorectal cancer cells and the related mechanism. A MTT assay was used to assess the growth of the colorectal cancer cells treated with penicillin and to determine the optimal drug concentration. The wound healing and Transwell invasion assays were performed to investigate the effect of penicillin on the migration and invasion of the colorectal cancer cells. Live cell mitochondrial energy metabolism analysis was performed to detect changes in mitochondrial energy metabolism of the colorectal cancer cells, while western blot analysis was used to measure the expression of cytochrome c and autophagy-related protein, LC3. RFP-GFP-LC3 lentivirus was used to detect autophagic flux, and autophagosomes were observed using a transmission electron microscope, while flow cytometry was used to analyze the effect of penicillin on cell cycle progression and apoptosis of the colorectal cancer cells. After penicillin treatment, the growth, migration and invasion ability of the colorectal cancer cells were inhibited. The mitochondrial energy metabolism of the cell was impaired, and the basic respiratory capacity, maximum respiratory capacity, respiratory potential, and ATP production were all reduced. The protein expression levels of the autophagy-related proteins, LC3-II/LC3-I increased in a dose- and time-dependent manner. In addition, autophagy flux and the number of autophagosomes increased, and mitochondrial structural damage was observed. The cell cycle was arrested at the G₁ phase, the number of early apoptotic cells increased and the protein expression level of cleaved caspase-3 increased, while penicillin-induced apoptosis was blocked by the autophagy inhibitor 3-MA. In conclusion, penicillin disrupted mitochondrial function and energy metabolism in the colorectal cancer cells, which resulted in the induction of autophagic apoptosis and ultimately the inhibition of cancer cell growth and metastasis.

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.

Lymph node retrieval after colorectal cancer surgery: a comparative study of the efficacy between the conventional manual method and a new fat dissolution method

PURPOSE

This study compared the efficacy of two different methods for lymph node (LN) searching after colorectal cancer surgery: the fat dissolution and the conventional manual method.

METHODS

For the fat dissolution method, we used a commercially available solution of collagenase and lipase (FD group). The primary endpoint was the number of identified LNs in the FD group compared to an historical control (control group) after adjusting by propensity score matching.

RESULTS

Using 37 matched patients from each group, we identified 20.6 ± 7.2 LNs using the fat dissolution method compared to 13.5 ± 5.9 using the conventional method (t test, P < 0.01). Three patients in the FD group received an inappropriate LN examination in terms of number, while the number of the retrieved LNs was < 12 in 12 patients in the control group. The mean diameter of LNs without metastasis was 3.2 ± 1.9 mm in the FD group, and 40% of metastasis cases were found in LNs < 5 mm in diameter. A pathological examination confirmed that using the fat resolution method did not change the morphological or immunochemical staining findings.

CONCLUSION

We demonstrated that fat dissolution had a positive impact on the number of retrieved LNs after colorectal cancer surgery without disturbing the microscopic observation.

Survival benefit of lymph node dissection in surgery for colon cancer in elderly patients: A multicenter propensity score-matched study in Japan

INTRODUCTION

In surgery for elderly patients with colorectal cancer, it is unclear whether radical lymph node (LN) dissection safely offers a survival benefit. The aim of the study was to evaluate the impact of the LN yield in elderly patients undergoing surgery for colorectal cancer.

METHODS

The subjects were selected from a surgical database of 2065 patients aged ≥80 years old who underwent surgery for colorectal cancer at 41 hospitals in Japan between 2003 and 2007. The patients were divided into groups according to the number LN harvested: <12 and ≥12. Propensity scores were subsequently matched to balance the baseline characteristics.

RESULTS

Of the 954 patients initially selected, 331 were in the <12 LN and 623 were in the ≥12 LN group. After cases were matched, 293 patients were allocated to each group, and all covariates were balanced. For short-term outcomes, the time for surgery was longer in the ≥12 LN group, but there was no significant difference in morbidity between the groups. Overall, relapse-free and cancer-specific survival rates were higher in the ≥12 LN group (P = 0.004, 0.001, and 0.02).

CONCLUSIONS

In patients aged ≥80 years old with stage II-III colon cancer, harvesting ≥12 LN provides a survival benefit, and therefore, limited LN dissection is not recommended in these patients.

Lymph node retrieval after dissolution of surrounding adipose tissue for pathological examination of colorectal cancer

Examination of >12 lymph nodes (LNs) is important for the diagnostic accuracy of nodal status following resection of colorectal cancer. In the present study, the efficacy of a fat dissolution technique for LN retrieval was evaluated using resected colon and rectum mesentery. First, the resected mesentery was searched for LNs by inspection and palpation immediately after surgery. Subsequently, fat dissolution liquid was applied to the remnant fat and the LN search was repeated. The primary endpoint was whether the second assessment would increase the number of evaluated LNs. Recruitment of 20 patients was planned. The study was conducted after institutional review board approval and written informed consent was obtained. Among 20 participants, 1 patient was excluded because LN dissection was not performed. The median number of LNs identified at the first and second assessments was 13 and 6, respectively, producing a significant increase in total LNs evaluated (13 vs. 20, respectively; P<0.01; paired t-test). One positive node was identified among the additionally identified LNs (0.9%, 1/107). The second assessment increased the number of LNs assessed to >12 in 4 patients, and although staging was not changed, the treatment was potentially altered in 2 stage II patients. The maximum diameter of the additionally obtained LNs was significantly smaller compared with those from the first assessment (4 vs. 7.7 mm, respectively; P<0.01; Wilcoxon signed-rank test). After the fat dissolution technique, the tumor cells were satisfactorily stained by carcinoembryonic antigen and cytokeratin-20. In conclusion, applying fat dissolution liquid to the remnant adipose tissue of the mesentery of the colon and rectum identified additional LNs. This method should be considered when insufficient LNs are identified after conventional LN retrieval.

12-Gene Recurrence Score Assay Stratifies the Recurrence Risk in Stage II/III Colon Cancer With Surgery Alone: The SUNRISE Study

PURPOSE

The 12-gene Recurrence Score assay has been validated in resected stage II colon cancer treated with or without chemotherapy and resected stage III disease treated with chemotherapy. This study evaluated the 12-gene Recurrence Score assay for stage II and III colon cancer without chemotherapy to reveal the natural course of recurrence risk in stage III disease.

METHODS

A cohort-sampling design was used. From 1,487 consecutive patients with stage II to III disease who had surgery alone, 630 patients were sampled for inclusion with a 1:2 ratio of recurrence and nonrecurrence. Sampling was stratified by stage (II v III). The assay was performed on formalin-fixed, paraffin-embedded primary cancer tissue. Association of the Recurrence Score result with recurrence-free interval (RFI) was assessed by using weighted Cox proportional hazards regression.

RESULTS

Overall, 597 of 630 patients were analyzable-247 patients had stage II, and 350 had stage III colon cancer. The continuous Recurrence Score was significantly associated with RFI after adjustment for disease stage (hazard ratio for a 25-unit increase in Recurrence Score, 2.05; 95% CI, 1.47 to 2.86; P < .001). With respect to prespecified subgroups, as defined by low (< 30), intermediate (30 to 40), and high (≥ 41) Recurrence Score risk groups, patients with stage II disease in the high-risk group had a 5-year risk of recurrence similar to patients with stage IIIA to IIIB disease in the low-risk group (19% v 20%), whereas patients with stage IIIA to IIIB disease in the high-risk group had a recurrence risk similar to that of patients with stage IIIC disease in the low-risk group (approximately 38%).

CONCLUSION

To our knowledge, this study provides the first validation of the 12-gene Recurrence Score assay in stage III colon cancer without chemotherapy and showed the heterogeneity of recurrence risks in stage III as well as in stage II colon cancer.