The Conventional Technique Versus the No-touch Isolation Technique for Primary Tumor Resection in Patients With Colon Cancer (JCOG1006): A Multicenter, Open-label, Randomized, Phase III Trial.

OBJECTIVE: This phase III trial evaluated whether the no touch was superior to the conventional in patients with cT3/T4 colon cancer. BACKGROUND: No touch involves ligating blood vessels that feed the primary tumor to limit cancer cell spreading. However, previous studies did not confirm the efficacy of the no touch. METHODS: This open-label, randomized, phase III trial was conducted at 30 Japanese centers. The eligibility criteria were histologically proven colon cancer; clinical classification of T3-4, N0-2, andM0; and patients aged 20 to 80years. Patients were randomized (1:1) to undergo open surgery with conventional or the no touch. Patients with pathological stage III disease received adjuvant capecitabine chemotherapy. The primary endpoint was disease-free survival (DFS) according to the intention-to-treat principle. RESULTS: Between January 2011 and November 2015, 853 patients were randomized to the conventional group (427 patients) or the no touch group (426 patients). The 3-year DFS were 77.3% [95% confidence interval (CI) 73.1%-81.0%] and 76.2% (95% CI 71.9%-80.0%) in the conventional and no touch groups, respectively. The superiority of no touch was not confirmed: hazard ratio for DFS = 1.029 (95% CI 0.800- 1.324; 1-sided P = 0.59). Operative morbidity was observed in 31 of 427 conventional patients (7%) and 26 of 426 no touch patients (6%). All grade adverse events were similar between the conventional and no touch groups. No in-hospital mortality occurred in either group. CONCLUSION: The present study failed to confirm the superiority of the no touch.

Oncological outcomes of lateral lymph node dissection (LLND) for locally advanced rectal cancer: is LLND alone sufficient?

BACKGROUND: Lateral lymph node dissection (LLND) has been considered as the standard treatment strategy for locally advanced lower rectal cancer in Japan. Controversy remains around whether all patients require LLND. This study aims to examine the long-term outcomes of patients in which LLND was performed and clarify the value of LLND. METHOD: Consecutive 458 patients with lower rectal cancer who underwent total mesorectal excision (TME) plus LLND from 1992 to 2012 were included. The long-term outcomes and risk factors for recurrent in patients performed TME + LLND were examined. We assessed the impact of LLND on survival using an estimated therapeutic index. RESULTS: The incidence of LLNM was 15.5%. The 5-year RFS and OS rates of patients with LLNM were 40.9% and 47.7%, while patients without LLNM had a good prognosis. The 5-year local recurrence (LR) rate was 9.2%, and independent risk factors for LR were T4 and LLNM. The LR rate of patients with LLNM was high (22.8%). The LLNM rate of the groups with 0, 1, 2, 3, or 4 risk factors (male, tumor location < 4 cm from anal verge, T4, and MLNM) was 3.8%, 9.2%, 18.1%, and 50.0%. The 5-year OS of the groups was 96.2%, 86.1%, 69.7%, and 48.5%. CONCLUSION: Although patients with locally advanced lower rectal cancer who received LLND had a good prognosis, LLND alone was insufficient to control local recurrence in patients with metastatic lateral nodes.

A New N Staging System for Colorectal Cancer in the Era of Extended Lymphadenectomy.

BACKGROUND: Complete mesocolic excision is becoming popular in colon cancer surgery in Western countries, and in the tumor-node-metastasis (TNM) classification of rectal cancer, a part of the lateral pelvic lymph nodes is classified as regional. However, the appropriateness of TNM staging according to the assessment of nodal status exclusively by extended lymphadenectomy remains unclear. PATIENTS AND METHODS: Using a nationwide multicenter database in Japan, we retrospectively analyzed 6866 patients with stage III colorectal cancer (CRC) treated with extended (D3) dissection. First, the best cutoff values for the number of metastatic nodes were explored. Second, the utility of the metastatic status of the main lymph nodes (i.e., at the origin of the feeding artery) and the lateral pelvic lymph nodes ("jN3" category in the Japanese staging system) as N staging criteria was evaluated. The modified N staging system that had the best risk stratification power was determined according to the Akaike information criterion (AIC). RESULTS: Excellent performance was noted when the number of metastatic nodes was categorized by cutoff values of "3/4" and "6/7." Categorization of nodal metastasis was proven the most clinically efficacious when classified as modified-N1 (N1 and jN3-negative), modified-N2a (N2a and jN3-negative), and modified-N2b (N2b and/or jN3-positive; AIC, 22,810.8), rather than the classification based on the TNM (AIC, 22,849.2) or Japanese staging system (AIC, 22,811.1). CONCLUSIONS: We structured a modified N staging system according to the number and extent of lymph node metastases. The modified system may be used in stage III cases for precise risk stratification.

[A Case of Neuroendocrine Tumor G1 of the Ileum with Multiple Liver Metastases].

A 74-year-old man was admitted to our hospital with multiple liver tumors detected by routine ultrasonography. Colonoscopy showed a type 2 tumor measuring approximately 25mm in diameter at the terminal ileum. The biopsy specimen showed neuroendocrine tumor(NET)G1. The patient was diagnosed with NET G1 of the ileum with multiple liver metastases. Thus, he underwent ileocecal resection with lymph node dissection and liver(S2)biopsy. A tumor was observed at the terminal ileum with serosal invasion, and the mesenteric lymph nodes were enlarged. Multiple liver metastatic tumors were observed in S2, S5, and S8. The patient was diagnosed with NET G1 of the ileum, T4N1M1, Stage Ⅳ. He is receiving octreotide therapy and has maintained stable disease for about 24 months.

[Gallbladder Malignant Lymphoma Diagnosed after Surgery for Acute Cholecystitis - A Case Report].

An 84-year-old man visited our hospital with epigastralgia.Levels of hepatic and biliary enzymes and CRP were elevated, as detected by a blood test.On a CT scan, a swollen gallbladder with stones was detected.The patient was admitted to the hospital with a diagnosis of Grade I acute cholecystitis.Conservative treatment was continued with antibiotic administration and the patient was discharged from the hospital with improvement on day 6 after admission.Three months later, the patient underwent laparoscopic cholecystectomy.In the gallbladder, a 45×45 mm tumor was found.Upon pathological examination, diffuse proliferation of lymphocyte-like heterotypic cells and subserosal invasion were observed.Immunohistochemistry results were negative for MUM1 and positive for CD10 and Bcl6 markers.A malignant diffuse large B-cell lymphoma was diagnosed.We experienced a case of malignant lymphoma of the gallbladder diagnosed after surgery for acute cholecystitis, which we herein report with literature consideration.

Prediction of lateral pelvic lymph node metastasis from lower rectal cancer using magnetic resonance imaging and risk factors for metastasis: Multicenter study of the Lymph Node Committee of the Japanese Society for Cancer of the Colon and Rectum.

PURPOSE: The goal of the study was to examine prediction of lateral pelvic lymph node (LPLN) metastasis from lower rectal cancer using a logistic model including risk factors for LPLN metastasis and magnetic resonance imaging (MRI) clinical LPLN (cLPLN) status, compared to prediction based on MRI alone. METHODS: The subjects were 272 patients with lower rectal cancer who underwent MRI prior to mesorectal excision combined with LPLN dissection (LPLD) at six institutes. No patients received neoadjuvant therapy. Prediction models for right and left pathological LPLN (pLPLN) metastasis were developed using cLPLN status, histopathological grade, and perirectal lymph node (PRLN) status. For evaluation, data for patients with left LPLD were substituted into the right-side equation and vice versa. RESULTS: Left LPLN metastasis was predicted using the right-side model with accuracy of 86.5%, sensitivity 56.4%, specificity 92.7%, positive predictive value (PPV) 61.1%, and negative predictive value (NPV) 91.2%, while these data using MRI cLPLN status alone were 80.4, 76.9, 81.2, 45.5, and 94.5%, respectively. Similarly, right LPLN metastasis was predicted using the left-side equation with accuracy of 83.8%, sensitivity 57.8%, specificity 90.4%, PPV 60.5%, and NPV 89.4%, and the equivalent data using MRI alone were 78.4, 68.9, 80.8, 47.7, and 91.1%, respectively. The AUCs for the right- and left-side equations were significantly higher than the equivalent AUCs for MRI cLPLN status alone. CONCLUSIONS: A logistic model including risk factors for LPLN metastasis and MRI findings had significantly better performance for prediction of LPLN metastasis compared with a model based on MRI findings alone.

Preplanned safety analysis of the JFMC37-0801 trial: a randomized phase III study of six months versus twelve months of capecitabine as adjuvant chemotherapy for stage III colon cancer.

BACKGROUND: Six months of adjuvant chemotherapy is regarded as the standard of care for patients with stage III colon cancer. However, whether longer treatment can improve prognosis has not been fully investigated. We conducted a phase III study comparing 6 and 12 months of adjuvant capecitabine chemotherapy for stage III colon cancer, and report here the results of our preplanned safety analysis. METHODS: Patients aged 20-79 years with curatively resected stage III colon cancer were randomly assigned to receive 8 cycles (6 months) or 16 cycles (12 months) of capecitabine (2500 mg/m2/day on days 1-14 of each 21-day cycle). Treatment exposure and adverse events (AEs) were evaluated. RESULTS: A total of 1304 patients (642 and 636 in the 6-month and 12-month groups, respectively) were analyzed. The most common AE was hand-foot syndrome (HFS). HFS, leukocytopenia, neutropenia, and hyperbilirubinemia (any grade) occurred more frequently in the 12-month group than in the 6-month group. HFS was the only grade ≥3 AE to have a significantly higher incidence in the 12-month group (23 vs 17%, p = 0.011). The completion rate for 8 cycles was 72% in both groups, while that for 16 cycles was 46% in the 12-month group. HFS was the most common AE requiring dose reduction and treatment discontinuation. CONCLUSIONS: Twelve months of adjuvant capecitabine demonstrated a higher cumulative incidence of HFS compared to the standard 6-month treatment period, while toxicities after 12 months of capecitabine were clinically acceptable. TRIAL REGISTRATION: UMIN-CTR, UMIN000001367.

[The Case of HER2 Positive Advanced Gastric Cancer with Para-Aorta Lymph Node Recurrence Responding to Capecitabine plus CDDP plus Trastuzumab Chemotherapy].

We report the case of a 69-year-old man diagnosed with gastric cancer.The patient underwent distal gastrectomy(D2) and Billroth I reconstruction in March, 2010. Postoperative histopathological examination indicated M, Ant, Type 5, 100×50 mm, pap>por2>sig, T4aN3M0, pStage III C.We performed S-1 therapy as adjuvant chemotherapy.Abdominal CT showed para-aortic lymph node recurrence in February, 2015. Since HER2 protein was overexpressed in primary tumor immunostaining, he was treated with capecitabine plus CDDP plus trastuzumab therapy.After the chemotherapy, CEA levels decreased to the normal range and the enlarged lymph node was remarkably decreased in size in May, 2015.T he patient is alive 24 months after the chemotherapy with no evidence of recurrence.

Selection of Lymph Node-Positive Cases Based on Perirectal and Lateral Pelvic Lymph Nodes Using Magnetic Resonance Imaging: Study of the Japanese Society for Cancer of the Colon and Rectum.

PURPOSE: To investigate the optimum cutoff for lymph node size to identify cases positive for perirectal lymph node (PRLN) and lateral lymph node (LPLN) metastasis of lower rectal cancer on magnetic resonance imaging (MRI). METHODS: The subjects were 449 patients who underwent preoperative MRI. Mesorectal excision was performed in all patients (combined with lateral pelvic lymph node [LN] dissection in 324) between 2004 and 2013 at 6 institutes. Cases were classified as cN positive and cN negative on the basis of the short axis of the largest LN being greater than or equal to a cutoff or less than a cutoff, respectively. PRLN and LPLN diagnoses using 5 and 10 mm cutoffs were compared with histologic diagnoses. Of the 449 patients, 55 received preoperative chemoradiotherapy. MRI was only performed after this therapy in all of these patients. RESULTS: For PRLNs, 5 and 10 mm cutoffs gave area under the curve (AUC) values of 0.6364 and 0.5794, respectively. The 5 mm cutoff gave a significantly higher AUC value (P = 0.0152), with an accuracy of 63.7 %, sensitivity of 72.6 %, and specificity of 54.7 %. For right LPLNs, the respective AUC values were 0.7418 and 0.6326 (P = 0.0034), and the variables (5 mm cutoff) were 77.6, 68.6, and 79.7 %. For left LPLNs, AUC values were 0.7593 and 0.6559, respectively (P = 0.0057), and the variables (5 mm cutoff) were 79.3, 70.8, and 81.0 %. CONCLUSIONS: Identification of LN-positive cases on the basis of PRLN and LPLN sizes was superior at a short-axis 5 mm cutoff. Size-based diagnosis of LN metastasis is simple and useful, but further investigation is needed to clarify whether it is superior to diagnosis based on morphology, such as shape, border, and signal intensity.

The important risk factor for lateral pelvic lymph node metastasis of lower rectal cancer is node-positive status on magnetic resonance imaging: study of the Lymph Node Committee of Japanese Society for Cancer of the Colon and Rectum.

PURPOSE: This study seeks to evaluate lateral pelvic lymph node (LPLN) and perirectal lymph node (PRLN) status on magnetic resonance imaging (MRI) as potential risk factors for lymph node metastasis. METHODS: The subjects were 394 patients with lower rectal cancer who underwent MRI prior to mesorectal excision (combined with lateral pelvic lymph node dissection in 272 patients) at 6 institutes. No patients received neoadjuvant therapy. Cases were classified as cN(+) and cN(-) based on the short axis of the largest lymph node ≥5 and <5 mm, respectively. LPLN and PRLN status and other clinicopathologic factors were analyzed by multivariate logistic regression. The importance of identified risk factors for lymph node metastasis was examined using the area under the curve (AUC). RESULTS: Independent risk factors for right LPLN metastasis included histopathological grade (G3 + G4), pPRLN(+), M1, cLPLN(+) [odds ratio (OR) 10.73, 95 % confidence interval (CI) 4.59-27.1], and those for left LPLN metastasis were age (<64), histopathological grade (G3 + G4), pPRLN(+), and cLPLN(+) (OR 24.53, 95 % CI 9.16-77.7). ORs for cLPLN(+) were highest. The AUCs for right and left cLPLN status of 0.7484 (95 % CI 0.6672-0.8153) and 0.7904 (95 % CI 0.7088-0.8538), respectively, were significantly higher than those for other risk factors. In contrast, the ORs for cPRLN(+) and cPRLN status of 2.46 (95 % CI 1.47-4.18) and 0.6396 (95 % CI 0.5917-0.6848) were not much higher than for other factors. CONCLUSIONS: An LPLN-positive status with a short axis ≥5 mm on MRI is an important predictor of LPLN metastasis, but PRLN status is not a strong predictor of PRLN metastasis.

[A Case of Stage IV Gastric Cancer Successfully Treated Using Salvage Surgery after S-1/CDDP Therapy].

A 75-year-old man admitted for left lateral abdominal pain was found to have advanced poorly differentiated gastric adenocarcinoma with abdominal para-aortic and Virchow's lymph node metastases, which was diagnosed to be clinical Stage IV (T3N3H0M1[LYM]). As curative surgery was not deemed possible, we started chemotherapy administration using S-1 (120mg/day)administered orally for 3 weeks and cisplatin(CDDP 100mg/body)administered intravenously on day 8. After 6 courses of chemotherapy, a CT scan showed that all lymph nodes metastases had disappeared, resulting in downstaging to clinical Stage II (T3[SE]N0H0P0M0). Thus, we performed total gastrectomy, lymph node dissection(D2), and splenectomy. Histological findings showed no residual tumor cells in any of the lymph nodes. However, cancer cells remained in the primary gastric lesion. The pathological response to chemotherapy was judged to be Grade 2. The patient has been recurrence-free for 5 years after surgery.

[Experience of the Pharmacotherapy against Appendix and Sigmoid Colon Signet Ring Cell Carcinoma with the Peritoneal Dissemination].

We report 2 cases of signet ring cell carcinoma of the appendix and colon. Case 1: A 61-year-old man was admitted for lower abdominal pain. Colonoscopy revealed an elevated lesion in the orifice of the appendix. Signet ring cell carcinoma was diagnosed on biopsy. The surgical findings showed multiple peritoneal dissemination nodules, while the primary tumor was unresectable owing to extensive invasion into the retroperitoneum. The histopathological findings were signet ring cell carcinoma, T4b (retroperitoneum), NX, P3, Stage Ⅳ. Although the patient received 14 courses of treatment with S-1 as postoperative chemotherapy, he died of his illness at 32 postoperative months. Case 2: A 76-year-old man was admitted for abdominal pain. Perforation of the lower gastrointestinal tract was diagnosed on abdominal CT, and an emergency operation was performed. The surgical findings demonstrated a large number of peritoneal dissemination nodules, cecal invasion of a sigmoid tumor, and perforation of the ascending colon. The primary tumor was thought to be unresectable, and the perforated segment was resected. The histopathological findings were signet ring cell carcinoma, T4b (cecum), NX, P3, Stage Ⅳ. Although 11 courses of treatment using FOLFIRI+Bev were administered as postoperative chemotherapy, the patient died of his illness at 26 postoperative months.

[The Outcomes of Laparoscopy-Assisted Surgery in Elderly Patients with Colorectal Carcinoma].

AIM: To evaluate short-term outcomes of laparoscopy-assisted colectomy (LAC) in elderly patients with colorectal carcinoma. METHODS: A total of 289 colorectal cancer patients underwent LAC between 2008 and 2013. They were divided into an elderly group (<80 years of age, group E), and a younger group (<80 years of age, group Y). The treatment results, including the surgery-related factors, the perioperative course, and the pre- and postoperative complications, were retrospectively analyzed. RESULTS: There were 49 patients in group E, and 240 patients in group Y. There was no significant difference between the 2 groups considering the operative time, blood loss, rate of transfusion, post-operative hospital stay, rate of conversion to open surgery, or rate of complications, except for the number of patients with an ASA classification of greater than Grade 2 and the degree of lymph node dissection. CONCLUSIONS: LAC in elderly patients was found to be relatively safe because it was associated with a reduction in damage to the abdominal wall, and with an early recovery from surgery. These results suggest that the indications of LAC could be expanded for elderly patients.

[Clinicopathological Features and Outcomes of Treatment for HER2 Positive Gastric Cancer].

In March 2011, trastuzumab was approved for treating human epidermal growth factor receptor 2 (HER2) positive advanced gastric cancer (AGC) in Japan. Therefore, all patients with AGC should be evaluated for HER2 status. In this study, we analyzed the clinicopathological features and current status of treatment in HER2 positive gastric cancer. One hundred 6 gastric cancer patients were examined for HER2 expression in our hospital between March 2011 and August 2014. Sixteen patients (15.1%) were HER2 positive. There was no correlation between HER2 status and age, sex, and location of tumor; however, HER2 positivity was significantly more frequent in patients with intestinal type tumors and had a tendency towards being more frequent in patients with macroscopic types 0, 1 or 2. Trastuzumab was administered to 10 patients with HER2 positive AGC. The total number of doses of trastuzumab was 1 to 44 (median 7.5), and the therapeutic effect of trastuzumab combination chemotherapy was 1 patient with a complete response and 4 with a partial response. Adverse events due to trastuzumab were not observed. The incidence of HER2 over-expression was 15.1%, and trastuzumab combination chemotherapy was relatively safe and effective.

[Outcomes of laparoscopic surgery after preoperative metallic stent placement for obstructive colorectal cancer].

AIM: To assess the outcomes of preoperative colonic stent placement for obstructive colorectal cancer. PATIENTS AND METHODS: A total of 30 patients with colorectal cancer were treated after preoperative colonic metallic stent placement between July 2012 and March 2014. We reviewed their medical records to assess the usefulness of stent placement and the clinical course. The effects of various clinicopathological variables on post-operative complications were analyzed statistically. RESULTS: Stent insertion was effective in 93% of the 30 patients with obstructive colorectal cancer. Preoperative colonoscopy or enema for proximal colonic survey was possible in 70% of the patients after stent placement; colonic lesions requiring simultaneous resection were noted in 5 patients (24%). The mean interval between stent insertion and operation was 19 days, and 23%of the patients underwent laparoscopic surgery. Statistical analysis revealed that the occurrence of complications was associated with laparoscopic surgery and the amount of operative blood loss. CONCLUSION: Preoperative stent placement in patients with obstructive colorectal cancer is feasible and laparoscopic surgery can be selected after stent placement.

Investigation of the safety of topical metronidazole from a pharmacokinetic perspective.

Metronidazole (MTZ) ointment has been used widely as a hospital preparation against cancerous malodor. Although cancerous tissue with ulcer-like symptoms is likely to have a higher capacity to absorb drugs than normal skin, the extent to which MTZ is absorbed when a topical preparation is applied to cancerous tissue remains unclear. Furthermore, few studies have investigated the drug interactions involving MTZ despite its long use in clinical practice. In the present study, plasma concentration of MTZ was measured in a breast cancer patient using MTZ ointment for cancerous malodor and basic research was also conducted with the objective of investigating the safety of topical MTZ from a pharmacokinetic perspective. 4.75 µg/mL (27.8 µM) of MTZ was detected in the patient's plasma, which was close to the plasma concentration after oral dosage of MTZ. In a metabolic inhibition study using human liver microsomes, cytochrome P450 (CYP) 2C9-mediated hydroxylation of S-warfarin was almost unaffected by MTZ at the corresponding concentrations. In addition, 3-d repeated oral administration of MTZ (200 mg/kg/d) to rats did not show any significant effects on the hepatic mRNA levels of various CYP isozymes and CYP2C protein levels. These results suggest that the reported interaction of oral MTZ and S-warfarin was not due to CYP2C9 inhibition and that drug interactions via inhibition of CYP2C9 is unlikely to occur when MTZ ointment is applied to ulcerous skin. This information should be valuable for assessing the safety of MTZ ointment used for mitigating cancerous malodor.

A multicenter cohort study on mapping of lymph node metastasis for splenic flexural colon cancer.

Aim: There have been no reports of searching for metastases to lymph nodes along the accessory middle colic artery (aMCA). The aim of this study was to investigate the metastasis rate of the aMCA for splenic flexural colon cancer. Methods: Patients with histologically proven colon carcinoma located in the splenic flexure, clinically diagnosed as stage I-III were eligible for this study. Patients were retrospectively and prospectively enrolled. The primary endpoint was frequency of lymph node metastasis to the aMCA (station 222-acc and 223-acc). The secondary endpoint was the frequency of lymph node metastasis to the middle colic artery (MCA) (station 222-lt and 223) and left colic artery (LCA) (station 232 and 253). Results: Between January 2013 and February 2021, a total of 153 consecutive patients were enrolled. The location of the tumor was 58% in the transverse colon and 42% in the descending colon. Lymph node metastases were observed in 49 cases (32%). The presence of aMCA rate was 41.8% (64 cases). The metastasis rates of stations 221, 222-lt, and 223 were 20.0%, 1.6%, and 0%, and stations 231, 232, and 253 were 21.4%, 1.0%, and 0%, respectively. The metastasis rates of stations 222-acc and 223-acc were 6.3% (95% confidence interval: 1.7%-15.2%) and 3.7% (95% confidence interval: 0.1%-19%), respectively. Conclusions: This study identified the distribution of lymph node metastases from splenic flexural colon cancer. If the aMCA is present, this vessel should be targeted for dissection, taking into account the frequency of lymph node metastasis.

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.

Optimizing nodal and staging classification in low rectal cancers with lateral node metastasis: multicentre retrospective cohort study.

BACKGROUND: Patients with lateral node metastasis in low rectal cancers have a poor prognosis. However, variability in patient survival in terms of lateral metastatic status has not been thoroughly investigated. This study was conducted to assess the prognostic value of lateral node involvement and to review nodal classification. METHODS: Patients with stage III low rectal cancers who underwent lateral node dissection were retrospectively reviewed. Two cohorts were set: the first one (1995-2006) was selected using a Japanese multi-institutional database and was used for development of a new nodal system, and the second (2007-2013) was collected from referral institutions for validation of findings. Variables correlated with poor prognosis were investigated. Next, a modified classification of lateral-positive nodal cancers was created. Finally, this new classification was compared with TNM and Japanese classification-based systems according to the Akaike information criterion (AIC) and concordance index (c-index). RESULTS: Overall, 742 and 508 patients were selected for cohorts 1 and 2, respectively. Based on the analyses on cohort 1, patients with two or more lateral metastatic nodes partially spreading into regions outside of internal iliac area exhibited poor prognosis; accordingly, a modified N classification was created, where TNM-N1 and N2a cancers with this feature were upgraded, respectively, to N2a and N2b. The modified N classification yielded the most favourable indices (AIC = 2661.08; c-index = 0.6477) compared with the TNM (AIC = 2662.36; c-index = 0.6457) and Japanese classification-based systems (AIC = 2684.06; c-index = 0.6302). All findings were confirmed by analysing cohort 2. CONCLUSION: A modified nodal system is proposed to account for the significance of lateral node metastasis.