Combined Pubic Arch and Ischial Bone Resection for Metachronous and Frequent Local Recurrences of Rectal Cancer.

BACKGROUND/AIM: Complete surgical resection with negative margins remains the cornerstone for curative treatment of rectal cancer; however, local recurrence can pose a significant challenge. Herein, we aimed to introduce a novel surgical technique for combined resection of the pubic arch and ischial bone in the context of treating recurrent rectal cancer. CASE REPORT: We present a case of a patient with a fourth local recurrence of rectal cancer, with no evidence of distant metastasis. The tumor directly invaded the posterior wall of the pubic arch. To achieve complete tumor resection, an osteotomy was performed using a thread wire saw at the bilateral pubic rami and ischial bones. Intraoperative frozen section analysis (rapid tissue examination) was conducted on tissue samples from the lateral margins of the planned osteotomy line. Samples were negative for adenocarcinoma (cancerous cells). The combined resection of the pubic arch and ischial bone was successfully performed with negative margins for adenocarcinoma, as confirmed by frozen section analysis. CONCLUSION: Mastery of the surgical technique for combined resection of the pubic arch and ischial bone may be clinically significant for achieving complete resection in cases of multiple resections for locally recurrent rectal cancer.

Risk factors affecting delay of initiating adjuvant chemotherapy for stage III colorectal cancer.

PURPOSE: Delay in initiating adjuvant chemotherapy (AC) after curative resection of colorectal cancer (CRC) has been reported to lead to poor prognosis, but few studies have looked at associated factors. This study aimed to identify risk factors for delay in initiating AC. METHODS: Data from 200 consecutive patients who underwent curative resection and AC for stage III CRC between 2013 and 2018 were retrospectively collected and analyzed. RESULTS: AC was initiated more than 8 weeks after surgery in 12.5% of patients (the delay group). Compared to those with no delay (the non-delay group), patients in the delay group had significantly higher rates of synchronous double cancers (2.3% vs. 16.0%, p = 0.001), preoperative bowel obstruction (10.3% vs. 32.0%, p = 0.003), laparotomy (56.0% vs. 80.0%, p = 0.02), concomitant resection (2.9% vs. 24.0%, p < 0.001), and postoperative complications (32.0% vs. 56.0%, p = 0.02), and a significantly longer length of hospital stay (median 12 vs. 30 days, p < 0.001). In multivariate analysis, synchronous double cancers (odds ratio 10.2, p = 0.008), preoperative bowel obstruction (odds ratio 4.6, p = 0.01), concomitant resection (odds ratio 5.2, p = 0.03), and postoperative complications of Clavien-Dindo grade ≥ IIIa (odds ratio 4.0, p = 0.03) were identified as independent risk factors for delay in initiating AC. CONCLUSION: Careful preoperative treatment planning for CRC patients with synchronous double cancers, preoperative bowel obstruction, and concomitant resection, and management for postoperative complication are necessary to avoid delay in initiating AC.

Artificial Intelligence Imaging Diagnosis Using Super-Resolution and 3D Shape for Lymph Node Metastasis of Low Rectal Cancer: A Pilot Study From a Single Center.

BACKGROUND: Although accurate preoperative diagnosis of lymph node metastasis is essential for optimizing treatment strategies for low rectal cancer, the accuracy of present diagnostic modalities has room for improvement. OBJECTIVE: To establish a high-precision diagnostic method for lymph node metastasis of low rectal cancer using artificial intelligence. DESIGN: A retrospective observational study. SETTINGS: A single cancer center and a college of engineering in Japan. PATIENTS: Patients with low rectal adenocarcinoma who underwent proctectomy, bilateral lateral pelvic lymph node dissection, and contrast-enhanced multi-detector row computed tomography (slice ≤1 mm) between July 2015 and August 2021 were included in the present study. All pelvic lymph nodes from the aortic bifurcation to the upper edge of the anal canal were extracted, regardless of whether within or beyond the total mesenteric excision area, and pathological diagnoses were annotated for training and validation. MAIN OUTCOME MEASURES: Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy. RESULTS: A total of 596 pathologically negative and 43 positive nodes from 52 patients were extracted and annotated. Four diagnostic methods, with and without using super-resolution images and without using 3D shape data, were performed and compared. The super-resolution + 3D shape data method had the best diagnostic ability for the combination of sensitivity, negative predictive value, and accuracy (0.964, 0.966, and 0.968, respectively), while the super-resolution only method had the best diagnostic ability for the combination of specificity and positive predictive value (0.994 and 0.993, respectively). LIMITATIONS: Small number of patients at a single center and the lack of external validation. CONCLUSIONS: Our results enlightened the potential of artificial intelligence for the method to become another game changer in the diagnosis and treatment of low rectal cancer. See Video Abstract.

Thoracoscopic salvage esophagectomy with prophylactic mediastinal lymph node dissection after definitive chemoradiotherapy for patients with esophageal cancer.

BACKGROUND: Salvage esophagectomy for residual tumor and localized relapses after definitive chemoradiotherapy (dCRT) for patients with esophageal cancer is associated with a high rate of postoperative complications and in-hospital mortality. In addition, there are many controversial issues associated with salvage esophagectomy, such as the acceptability of minimally invasive surgery and the need for prophylactic dissection of mediastinal lymph nodes. The aim of this study was to evaluate the safety and usefulness of thoracoscopic salvage esophagectomy with prophylactic mediastinal lymph node dissection. METHODS: The study included 31 patients who underwent thoracoscopic salvage esophagectomy with prophylactic mediastinal lymph node dissection after dCRT between 2013 and 2022 (salvage patients) and 610 nonsalvage patients who underwent conventional thoracoscopic esophagectomy during the same time period. RESULTS: Differences between the median ages and sexes of the 2 patient groups were not significant. The dominant location of tumors in the salvage patients was the upper thoracic esophagus. More salvage patients had clinical T4 disease. The salvage patients had a lower median number of retrieved mediastinal lymph nodes than the nonsalvage patients. The differences between the rates of R0, postoperative complications, and in-hospital deaths in the 2 patient groups were not significant. The 3-year overall survival (OS) rates for the salvage patients were 73%, with 3-year OS rates for R0 vs non-R0 of 81% vs 0%, p < 0.01 and pN0 vs pN1-3 of 89% vs 49%, p < 0.01. CONCLUSION: Regarding short-term outcomes, prophylactic mediastinal lymph node dissection for patients undergoing thoracoscopic salvage esophagectomy was as safe as prophylactic dissection for patients undergoing conventional thoracoscopic esophagectomy. R0 surgery and pN0 are important factors for long-term survival in patients undergoing thoracoscopic salvage esophagectomy.

A case of acinar cell carcinoma originating from the accessory papilla of the duodenum.

CASE PRESENTATION: A 61-year-old female was referred to our hospital with a neoplastic lesion in the duodenum. Computed tomography with contrast enhancement revealed a 10-mm tumor in the duodenum. Upper gastrointestinal endoscopy revealed a submucosal tumor-like lesion in the descending part of the duodenum. Endoscopic ultrasound revealed a well-defined hypoechoic tumor. Biopsy and immunohistochemical findings including negative Synaptophysin and Chromogranin A staining and positive Trypsin and BCL10 staining suggested a carcinoma with acinar cell differentiation. Pancreatoduodenectomy was performed, and the resected specimen had a 15-mm solid nodule in the submucosal layer of the duodenum. Pancreatogram of the resected specimen revealed a tumor localized in the accessory papilla region. In histopathological examination, the tumor was found in the submucosa of the duodenum with pancreatic tissue present nearby, and these were separated from the pancreatic parenchyma by the duodenal muscle layer. These findings led to a diagnosis of acinar cell carcinoma originating from the accessory papilla of the duodenum. CONCLUSION: Acinar cell carcinoma originating from the accessory papilla of the duodenum is exceptionally rare, with no reported cases to date. The origin was considered to be pancreatic tissue located in the accessory papilla region.

Factors Affecting Nonfunctioning Small Pancreatic Neuroendocrine Neoplasms and Proposed New Treatment Strategies.

BACKGROUND & AIMS: Despite previously reported treatment strategies for nonfunctioning small (≤20 mm) pancreatic neuroendocrine neoplasms (pNENs), uncertainties persist. We aimed to evaluate the surgically resected cases of nonfunctioning small pNENs (NF-spNENs) in a large Japanese cohort to elucidate an optimal treatment strategy for NF-spNENs. METHODS: In this Japanese multicenter study, data were retrospectively collected from patients who underwent pancreatectomy between January 1996 and December 2019, were pathologically diagnosed with pNEN, and were treated according to the World Health Organization 2019 classification. Overall, 1490 patients met the eligibility criteria, and 1014 were included in the analysis cohort. RESULTS: In the analysis cohort, 606 patients (59.8%) had NF-spNENs, with 82% classified as grade 1 (NET-G1) and 18% as grade 2 (NET-G2) or higher. The incidence of lymph node metastasis (N1) by grade was significantly higher in NET-G2 (G1: 3.1% vs G2: 15.0%). Independent factors contributing to N1 were NET-G2 or higher and tumor diameter ≥15 mm. The predictive ability of tumor size for N1 was high. Independent factors contributing to recurrence included multiple lesions, NET-G2 or higher, tumor diameter ≥15 mm, and N1. However, the independent factor contributing to survival was tumor grade (NET-G2 or higher). The appropriate timing for surgical resection of NET-G1 and NET-G2 or higher was when tumors were >20 and >10 mm, respectively. For neoplasms with unknown preoperative grades, tumor size >15 mm was considered appropriate. CONCLUSIONS: NF-spNENs are heterogeneous with varying levels of malignancy. Therefore, treatment strategies based on tumor size alone can be unreliable; personalized treatment strategies that consider tumor grading are preferable.

Heparan Sulfate Chain-Conjugated Laminin-E8 Fragments Advance Paraxial Mesodermal Differentiation Followed by High Myogenic Induction from hiPSCs.

Human-induced pluripotent stem cells (hiPSCs) have great therapeutic potential. The cell source differentiated from hiPSCs requires xeno-free and robust methods for lineage-specific differentiation. Here, a system is described for differentiating hiPSCs on new generation laminin fragments (NGLFs), a recombinant form of a laminin E8 fragment conjugated to the heparan sulfate chains (HS) attachment domain of perlecan. Using NGLFs, hiPSCs are highly promoted to direct differentiation into a paraxial mesoderm state with high-efficiency muscle lineage generation. HS conjugation to the C-terminus of Laminin E8 fragments brings fibroblast growth factors (FGFs) bound to the HS close to the cell surface of hiPSCs, thereby facilitating stronger FGF signaling pathways stimulation and initiating HOX gene expression, which triggers the paraxial mesoderm differentiation of hiPSCs. This highly efficient differentiation system can provide a roadmap for paraxial mesoderm development and an infinite source of myocytes and muscle stem cells for disease modeling and regenerative medicine.

BARD1 deletion in a patient with suspected hereditary colorectal cancer.

Deleterious germline variants in the BRCA1-associated ring domain (BARD1) gene moderately elevate breast cancer risk; however, their potential association with other neoplasms remains unclear. Here, we present the case of a 43-year-old female patient diagnosed with sigmoid colon adenocarcinoma whose maternal family members met the Amsterdam Criteria II for Lynch syndrome. Comprehensive multigene panel testing revealed a heterozygous BARD1 exon 3 deletion.

Novel Repair Technique for Oral and Anal Side Stoma Prolapse of a Loop Colostomy With the Stapled Modified Altemeier Method Using Indocyanine Green Fluorescence Imaging.

BACKGROUND/AIM: Stoma prolapse is a common complication in the late phase after stoma creation. With advances in chemotherapy, a double-orifice colostomy or ileostomy and chemotherapy are used to treat primary unresectable colorectal cancer. Preoperative therapy with a double-orifice colostomy or ileostomy is performed to aid primary colorectal cancer miniaturization. Therefore, the number of stoma prolapses will likely increase in the future. Previous reports on the repair of stoma prolapse focused on unilateral stoma prolapse of loop colostomy, and there are no reports about the bilateral stoma prolapse of loop colostomy or ileostomy. CASE REPORT: We report a novel repair technique for oral and anal side (bilateral) stoma prolapse of a loop colostomy with the stapled modified Altemeier method using indocyanine green (ICG) fluorescence imaging considering the distribution of marginal artery in preventing marginal artery injury which has considerable clinical significance. CONCLUSION: Our novel technique for the oral and anal side prolapse of a loop colostomy is considered effective and safe.

A Japanese school urine screening program led to the diagnosis of KCNJ11-MODY: A case report.

Although KCNJ11 mutation is the main cause of neonatal diabetes mellitus, reports of maturity-onset diabetes in the young (MODY) related to KCNJ11 are rare. Here, we report a case of KCNJ11-MODY in a 12-yr-old Japanese female. Hyperglycemia was initially detected during a school urine screening program. Subsequent laboratory examinations revealed impaired insulin secretion; however, no islet autoantibodies were detected. Genetic testing of KCNJ11 revealed a novel heterozygous variant, c.153G>C, p.Glu51Asp. The patient's father had the same mutation and was diagnosed with diabetes at 46 yr of age. KCNJ11-MODY was suspected, and sulfonylurea administration resulted in adequate glycemic control in the patient. The American College of Medical Genetics and Genomics guidelines classify this variant as likely pathogenic, and the effectiveness of sulfonylureas supports its pathogenicity. The patient could be treated with 0.02-0.03 mg/kg/d of glibenclamide, as this mutation may be responsive to only a small amount of sulfonylurea. A detailed family history and sequencing of causative genes, including KCNJ11, may help diagnose diabetes in school-aged patients.

Critical swallowing functions contributing to dysphagia in patients with recurrent laryngeal nerve paralysis after esophagectomy.

BACKGROUND: Recurrent laryngeal nerve paralysis (RLNP) after esophagectomy can cause aspiration because of incomplete glottis closure, leading to pneumonia. However, patients with RLNP often have preserved swallowing function. This study investigated factors that determine swallowing function in patients with RLNP. METHODS: Patients with esophageal cancer who underwent esophagectomy and cervical esophagogastric anastomosis were enrolled between 2017 and 2020. Videofluoroscopic examination of swallowing study (VFSS) and acoustic voice analysis were performed on patients with suspected dysphagia including RLNP. Dysphagia in VFSS was defined as score ≥ 3 of the 8-point penetration-aspiration scale VFSS and acoustic analysis results related to dysphagia were compared between patients with and without RLNP. RESULTS: Among 312 patients who underwent esophagectomy, 74 developed RLNP. The incidence of late-onset pneumonia was significantly higher in the RLNP group than in the non-RLNP (18.9 vs. 8.0%, P = .008). Detailed swallowing function was assessed by VFSS in 84 patients, and patients with RLNP and dysphagia showed significantly shorter maximum diagonal hyoid bone elevation (10.62 vs. 16.75 mm; P = .003), which was a specific finding not seen in patients without RLNP. For acoustic voice analysis, the degree of hoarseness was not closely related to dysphagia. The length of oral intake rehabilitation for patients with and without RLNP was comparable if they did not present with dysphagia (8.5 vs. 9.0 days). CONCLUSIONS: Impaired hyoid bone elevation is a specific dysphagia factor in patients with RLNP, suggesting compensatory epiglottis inversion by hyoid bone elevation is important for incomplete glottis closure caused by RLNP.

Genetic architecture of alcohol consumption identified by a genotype-stratified GWAS and impact on esophageal cancer risk in Japanese people.

An East Asian-specific variant on aldehyde dehydrogenase 2 (ALDH2 rs671, G>A) is the major genetic determinant of alcohol consumption. We performed an rs671 genotype-stratified genome-wide association study meta-analysis of alcohol consumption in 175,672 Japanese individuals to explore gene-gene interactions with rs671 behind drinking behavior. The analysis identified three genome-wide significant loci (GCKR, KLB, and ADH1B) in wild-type homozygotes and six (GCKR, ADH1B, ALDH1B1, ALDH1A1, ALDH2, and GOT2) in heterozygotes, with five showing genome-wide significant interaction with rs671. Genetic correlation analyses revealed ancestry-specific genetic architecture in heterozygotes. Of the discovered loci, four (GCKR, ADH1B, ALDH1A1, and ALDH2) were suggested to interact with rs671 in the risk of esophageal cancer, a representative alcohol-related disease. Our results identify the genotype-specific genetic architecture of alcohol consumption and reveal its potential impact on alcohol-related disease risk.

Is preoperative pancreatic juice cytology useful for determining therapeutic strategies for patients with intraductal papillary mucinous neoplasm of the pancreas?

BACKGROUND: We compared the results of preoperative pancreatic juice cytology (PJC) and final pathological diagnosis after resection in patients who underwent resection of intraductal papillary mucinous neoplasm (IPMN) of the pancreas to determine whether preoperative PJC can help determine therapeutic strategies. METHODS: Of 1130 patients who underwent surgical resection IPMN at 11 Japanese tertiary institutions, the study included 852 patients who underwent preoperative PJC guided by endoscopic retrograde cholangiopancreatography (ERCP). RESULTS: The accuracy of preoperative PJC for differentiation between cancerous and noncancerous lesions were 55% for IPMN overall; 59% for the branch duct type; 49% for the main pancreatic duct type; 53% for the mixed type, respectively. On classifying IPMN according to the diameters of the mural nodule (MN) and main pancreatic duct (MPD), the corresponding values for diagnostic performance were 40% for type 1 (MN ≥5 mm and MPD ≥ 10 mm); 46% for type 2 (MN ≥5 mm and MPD < 10 mm); 61% for type 3 (MN < 5 mm and MPD ≥ 10 mm); 72% for type 4 (MN < 5 mm and MPD < 10 mm), respectively. CONCLUSIONS: PJC in IPMN is not a recommended examination because of its low overall sensitivity and no significant difference in diagnostic performance by type, location, or subclassification. Although the sensitivity is low, the positive predictive value is high, so we suggest that pancreatic juice cytology be performed only in cases where the patient is not sure about surgery.

Feasibility of S-1 adjuvant chemotherapy after major hepatectomy for biliary tract cancers: An exploratory subset analysis of JCOG1202.

INTRODUCTION: Major hepatectomy (MH) may produce the impaired liver function and affect the feasibility of adjuvant chemotherapy in terms of early period after the surgery, but there have not been detailed investigations. JCOG1202 (UMIN000011688) is a randomized phase III trial demonstrating the superiority of adjuvant S-1 chemotherapy for biliary tract cancer (BTC). The aim of this study is to examine the influence of MH for BTC on adjuvant S-1. MATERIALS AND METHODS: Of the total 424 patients, 207 received S-1 (S-1 arm) while the remaining 217 were not. We compared MH with non-major hepatectomy (NMH) for BTC. RESULTS: In the S-1 arm, 42 had undergone MH, and 165 had undergone NMH. MH had similar pretreatment features to NMH, including the proportion of biliary reconstruction, to NMH, except for a lower platelet count (17.7 vs. 23.4 × 104/mm3, p < 0.0001) and lower serum albumin level (3.5 vs. 3.8 g/dL, p < 0.0001). The treatment completion proportion tended to be lower for MH than for NMH (59.5 % vs. 75.8 %; risk ratio, 0.786 [95 % confidence interval, 0.603-1.023], p = 0.0733), and the median dose intensity was lower as well (88.7 % vs. 99.6 %, p = 0.0358). The major reasons for discontinuation were biliary tract infections and gastrointestinal disorders after MH. The frequency of grade 3-4 biliary tract infection was 19.0 % in MH vs. 4.2 % in NMH. CONCLUSION: The treatment completion proportion and dose intensity were lower in MH than in NMH. Caution should be exercised against biliary tract infections and gastrointestinal disorders during adjuvant S-1 after MH for BTC.

A case of simultaneous breast cancer and ovarian cancer based on a hereditary breast and ovarian cancer syndrome.

We experienced a relatively rare case of synchronous breast and ovarian cancer in a patient with hereditary breast and ovarian cancer syndrome (HBOC). Here, we report the usefulness of laparoscopic examination to determine the subsequent treatment strategy in cases of suspected concurrent multiple carcinomas. Our patient was diagnosed with breast cancer following detection of a right breast mass. She was diagnosed with HBOC as she was found to be harboring a germline pathogenic variant of breast cancer susceptibility gene 1 (BRCA1). Preoperative images suggested the presence of neoplastic masses in the abdominal cavity, and the possibility of metastatic peritoneal dissemination of breast cancer or concurrent overlapping of gynecological malignancies was considered. We decided to employ laparoscopic examination, and if simultaneous overlapping of cancers was suspected, we planned to further evaluate whether primary debulking surgery (PDS) for gynecological cancer was possible or not. Laparoscopy revealed the presence of ovarian cancer with neoplastic lesions on the bilateral ovaries and disseminations in the pelvic and abdominal cavities. The total predictive index was 0; therefore, PDS was considered feasible. We performed a total mastectomy, followed by laparotomy, and optimal surgery was achieved. The final diagnosis was simultaneous stage IIB invasive ductal breast carcinoma and stage IIIC high-grade serous ovarian carcinoma. In this case of suspected concurrent multiple carcinomas, laparoscopy was beneficial for decision-making regarding subsequent surgical treatment. We believe that the use of laparoscopy will enable simultaneous surgery for breast cancer and ovarian cancer to become one of the treatment strategies in the future.

Three cases of open surgical procedures on ileal conduits for the repair of benign ureteroenteric anastomotic strictures after total pelvic exenteration of rectal tumors.

Ureteroenteric anastomotic strictures (UEAS) are typical complications after creating an ileal conduit for total pelvic exenteration (TPE) of rectal tumors. We report the ileal conduit for reconstruction in three patients, in the age-range of 47-73 years. Case 1 was when a left-sided UEAS had sufficient length of ureter for anastomosis, Case 2 was a right-sided UEAS with sufficient length of ureter for anastomosis, and Case 3 was a left-sided UEAS with insufficient length of ureter for anastomosis. There were no complications after operation and no recurrence of UEAS. It is important to learn the open surgical procedures for repair of a benign UEAS after TPE of rectal cancers. This has fewer complications and is safe in the long term.

How many times can patients tolerate reoperation for the local recurrence of colorectal cancer in terms of complications?

The frequency of resection for the recurrence of colorectal cancer has not been investigated in previous studies. Likewise, the related postoperative complications and the limit for indicating surgical resection has not been reported. Herein, we reported the complications of a highly frequent surgical approach for rectal cancer recurrence, i.e., exceeding three reoperations, based on our clinical experience. We included 15 cases exceeding two operations for the local recurrence of colorectal cancer from 2014 to 2019. We examined the postoperative complications classified as Clavien?Dindo IIIb. The positive rates of the complications were 0 (0.0%), 0 (0.0%), 2 (13.3%), 3 (37.5%), and 0 (0.0%) for the primary, 1st recurrent, 2nd recurrent, 3rd recurrent, and 4th recurrent operation group (p=0.027), respectively. It is important to exercise caution in handling cases exceeding two reoperations (exceeding three reoperations including the primary operation). J. Med. Invest. 70 : 369-376, August, 2023.

Novel Ureteral Stent Catheterization Technique for Treating Hyperchloremic Metabolic Acidosis After Total Pelvic Exenteration.

BACKGROUND/AIM: Hyperchloremic metabolic acidosis after total pelvic exenteration (TPE) is relatively rare. Urinary diversion of the ileal conduit during TPE can result in increased urine reabsorption leading to hyperchloremic metabolic acidosis. We developed a new technique for the retrograde catheterization of a ureteral stent into an ileal conduit to treat hyperchloremic metabolic acidosis. CASE REPORT: A 70-year-old man underwent TPE for locally recurrent rectal cancer. Multiple episodes of complications, such as hyperchloremia and metabolic acidosis, occurred. Effective drainage of urine from the ileal conduit is crucial. With collaboration between an endoscopist and a radiologist, we developed a novel method for retrograde catheterization of the ureteral stent into an ileal conduit for hyperchloremic metabolic acidosis after TPE. The patient's condition quickly improved after the procedure. CONCLUSION: Our novel technique of retrograde catheterization of a ureteral stent into an ileal conduit for hyperchloremic metabolic acidosis could be adopted worldwide, as it is effective and safe.

Feasibility of Surveillance for Mucinous Cystic Neoplasm of the Pancreas: A Multi-Institutional Retrospective Study of 328 Patients by the Japanese Pancreatic Society.

OBJECTIVE: We aimed to elucidate the feasibility of surveillance of patients with mucinous cystic neoplasm (MCN). METHODS: We performed a retrospective, multi-institutional study of 328 patients who underwent surgery for MCN at 18 Japanese institutions. Patients with MCN were divided into an immediate surgery group and a surveillance group, which underwent surgery after surveillance. RESULTS: The median surveillance period until surgery in the surveillance group was 27 months (range, 7-165 months). Compared with the immediate surgery group, the surveillance group showed smaller tumor diameter (46 vs 50 mm, P = 0.01), more frequent laparoscopic approach (58% vs 37%, P < 0.01), and less frequent malignancy (7% vs 15%, P = 0.03). The new appearance of mural nodules and elevation of serum tumor markers were associated with malignancy in the surveillance group. Two patients in the surveillance group experienced postoperative recurrence, although there was no significant difference in recurrence or disease-free survival between the two groups. In the surveillance group, the 1-, 5-, and 10-year cumulative incidence rates of malignant MCN were 0.8%, 5.6%, and 36.5%, respectively. CONCLUSION: As the risk of progression to malignant MCNs increases over the long term, MCNs should be resected rather than subjected to unnecessary surveillance.

Clinical Impact of Radical Resection of Synchronous and Metachronous Peritoneal Metastases from Colorectal Cancer.

BACKGROUND: According to some case series, patients with colorectal cancer (CRC) who underwent radical resection of synchronous peritoneal metastases (PM) with the primary tumor had better survival than patients who underwent non-surgical treatment. However, little evidence exists regarding the significance of radical resection for metachronous PM. OBJECTIVE: This study aimed to evaluate the clinical significance of surgical intervention for isolated PM from CRC, with a particular focus on time to PM. METHODS: A total of 74 consecutive patients with isolated PM from CRC, including 40 and 34 patients with synchronous and metachronous PM, respectively, treated between 2007 and 2018 were retrospectively analyzed. The primary outcome measure was overall survival (OS) from diagnosis, and the OS was compared between radical resection and palliative chemotherapy. RESULTS: Five-year OS was 39.7% for all patients. Patients with radical resection had significantly better 5-year OS compared with those with palliative chemotherapy (62.8% vs. 11.0%; p < 0.0001). According to time to PM, patients with radical resection had significantly better 5-year OS compared with those with palliative chemotherapy for both synchronous PM (47.6% vs. 0%; p = 0.019) and metachronous PM (77.2% vs. 15.2%; p < 0.0001). Multivariable analysis stratified by time to PM revealed that surgical intervention is a significant favorable prognostic factor only in patients with metachronous PM (hazard ratio 0.117, 95% confidence interval 0.020-0.678; p = 0.017). CONCLUSIONS: Patients with radical resection of PM had good survival compared with those with chemotherapy alone, especially for metachronous PM. Surgical intervention should be considered for isolated metachronous PM when radical resection is feasible.