Laparoscopic versus open colectomy for locally advanced colon cancer in obese patients: a nationwide, multicenter, propensity score-based analysis of short- and long-term outcomes.

OBJECTIVE: This study evaluated the short-and long-term outcomes of laparoscopic colectomy versus open surgery in obese patients (body mass index ≥25 kg/m2) with locally advanced colon cancer to ascertain the non-inferiority of laparoscopic surgery to open surgery. METHODS: In this large cohort study (UMIN-ID: UMIN000033529), we retrospectively reviewed prospectively collected data from consecutive patients who underwent laparoscopic or open surgery for pathological stage II-III colon cancer between 2009 and 2013. A comparative analysis was performed after propensity score matching between the laparoscopic and open surgery groups. The primary endpoint was the 3-year relapse-free survival (RFS). RESULTS: We identified 1575 eligible patients from 46 institutions. Each group comprised 526 propensity score-matched patients. Comparing the laparoscopic versus open surgery group, laparoscopic surgery was significantly associated with increased median operating time (225 vs. 192.5 min; P < .0001) and decreased median estimated blood loss (20 vs. 140 ml; P < .0001). Lymph node retrieval (20 vs. 19; P = 0.4392) and postoperative complications (4.6% vs. 5.7%; P = 0.4851) were similar, postoperative hospital stay was shorter (10 vs. 12 days; P < .0001), and the 3-year RFS rates were similar (82.8 vs. 81.2%). The hazard ratio (HR) for relapse-free survival for laparoscopic versus open surgery was 0.927 (90% confidence interval [CI], 0.747-1.150, one-sided P for non-inferiority = .001), indicating that for obese patients with colon cancer, laparoscopic surgery was non-inferior to open surgery. CONCLUSION: Laparoscopic surgery in obese patients with colon cancer offers advantages in terms of short-term outcomes and no disadvantages in terms of long-term outcomes.

Risk factors for anastomotic leakage after low anterior resection for obese patients with rectal cancer.

PURPOSE: We aimed to analyze the risk factors for anastomotic leakage (AL) after low anterior resection (LAR) in obese patients (body mass index [BMI] ≥ 25 kg/m2) with rectal cancer. METHODS: Data were collected from four hundred two obese patients who underwent LAR for rectal cancer in 51 institutions. RESULTS: Forty-six (11.4%) patients had clinical AL. The median BMI (27 kg/m2) did not differ between the AL and non-AL groups. In the AL group, comorbid respiratory disease was more common (p = 0.025), and the median tumor size was larger (p = 0.002). The incidence of AL was 11.5% in the open surgery subgroup and 11.4% in the laparoscopic surgery subgroup. Among the patients who underwent open surgery, the AL group showed a male predominance (p = 0.04) in the univariate analysis, but it was not statistically significant in the multivariate analysis. Among the patients who underwent laparoscopic surgery, the AL group included a higher proportion of patients with comorbid respiratory disease (p = 0.003) and larger tumors (p = 0.007). CONCLUSION: Comorbid respiratory disease and tumor size were risk factors for AL in obese patients with rectal cancer. Careful perioperative respiratory management and appropriate selection of surgical procedures are required for obese rectal cancer patients with respiratory diseases.

Impact of laparoscopic surgery on short-term and long-term outcomes in elderly obese patients with colon cancer.

Background: Laparoscopic surgery is reported to be useful in obese or elderly patients with colon cancer, who are at increased risk of postoperative complications because of comorbidities and physical decline. However, its usefulness is less clear in patients who are both elderly and obese and may be at high risk of complications. Methods: Data for obese patients (body mass index ≥25) who underwent laparoscopic or open surgery for stage II or III colon cancer between January 2009 and December 2013 were collected by the Japan Society of Laparoscopic Colorectal Surgery. Surgical outcomes, postoperative complications, and relapse-free survival (RFS) were compared between patients who underwent open surgery and those who underwent laparoscopic surgery according to whether they were elderly (≥70 y) or nonelderly (<70 y). Results: Data of 1549 patients (elderly, n = 598; nonelderly, n = 951) satisfied the selection criteria for analysis. Length of stay was shorter and surgical wound infection was less common in elderly obese patients who underwent laparoscopic surgery than in those underwent open surgery. There were no significant between-group differences in overall complications, anastomotic leakage, ileus/small bowel obstruction, or RFS. There were also no significant differences in RFS after laparoscopic surgery according to patient age. Conclusion: Laparoscopic surgery is safe in elderly obese patients with colon cancer and does not worsen their prognosis. There was no significant difference in the effectiveness of laparoscopic surgery between obese patients who were elderly and those who were nonelderly.

Local recurrence of submucosal invasive colorectal cancer after endoscopic submucosal dissection revealed by copy number variation.

We report a case in which analysis of copy number variation revealed local recurrence of submucosal invasive colorectal cancer after curative endoscopic submucosal dissection (ESD). An 86-year-old man with a history of abdominoperineal resection of the rectum for rectal cancer underwent resection with ESD for early-stage sigmoid cancer 5 cm away from the stoma opening. At the same time, ileocecal resection was performed for advanced cecal cancer. Twelve months after ESD, advanced cancer occurred in the area of the ESD lesion. It was unclear if the cancer was a local recurrence after ESD, implantation of cecal cancer, or a new lesion. Copy number variation analysis performed for the three lesions revealed that the new lesion originated from residual tumor cells from ESD and was unlikely to be cecal cancer.

Examination of colorectal cancer cases with metal allergy.

PURPOSE: To report our initiatives and treatment results for patients with colorectal cancer with metal allergy. METHODS: A total of 27 patients (2.6%) with a history of metal contact dermatitis were identified among 1027 patients who underwent curative resection of colorectal cancer from 2014 to 2020. The results of the patch test, perioperative results, and postoperative colonoscopy findings were also investigated. RESULTS: The patch test for metal allergens and staples was performed in 21 patients (77.8%), and 13 of them (61.9%) tested positive for at least one metal allergen. Ni (38.1%), Co (28.6%), and Pd (19.0%) showed higher positive rates than other metals, and 1 patient (4.8%) tested positive for staples. Stapled anastomosis/suturing was performed as planned in 15 of 27 patients. In 10 patients, the anastomosis method was changed from stapled to hand-sewn according to the no-patch test results (60%), positivity for multiple metals (20%), positivity for staples (10%), and surgeon's judgment (10%). No complications and abnormal colonoscopy findings were found to be associated with stapled anastomosis/suturing. CONCLUSION: The patch test is useful for selecting an optimal anastomosis method for patients with suspected metal allergy.

Do postoperative infectious complications really affect long-term survival in colorectal cancer surgery? A multicenter retrospective cohort study.

Aim: To investigate the impact of postoperative infection (PI), surgical site infection, and remote infection (RI), on long-term outcomes in patients with colorectal cancer (CRC). Methods: The Japan Society for Surgical Infection conducted a multicenter retrospective cohort study involving 1817 curative stage I/II/III CRC patients from April 2013 to March 2015. Patients were divided into the No-PI group and the PI group. We examined the association between PI and oncological outcomes for cancer-specific survival (CSS) and overall survival (OS) using Cox proportional hazards models and propensity score matching. Results: Two hundred and ninety-nine patients (16.5%) had PIs. The 5-year CSS and OS rates in the No-PI and PI groups were 92.8% and 87.6%, and 87.4% and 83.8%, respectively. Both the Cox proportional hazards models and propensity score matching demonstrated a significantly worse prognosis in the PI group than that in the No-PI group for CSS (hazard ratio: 1.60; 95% confidence interval: 1.10-2.34; P = .015 and P = .031, respectively) but not for OS. RI and the PI severity were not associated with oncological outcomes. The presence of PI abolished the survival benefit of adjuvant chemotherapy. Conclusions: These results suggest that PI after curative CRC surgery is associated with impaired oncological outcomes. This survival disadvantage of PI was primarily derived from surgical site infection, not RI, and PI induced lower efficacy of adjuvant chemotherapy. Strategies to prevent PI and implement appropriate postoperative treatment may improve the quality of care and oncological outcomes in patients undergoing curative CRC surgery.

Benefits and risks of diverting stoma creation during rectal cancer surgery.

Purpose: A consensus has been reached regarding diverting stoma (DS) construction in rectal cancer surgery to avoid reoperation related to anastomotic leakage. However, the incidence of stoma-related complications (SRCs) remains high. In this study, we examined the perioperative outcomes of DS construction in patients who underwent sphincter-preserving surgery for rectal cancer. Methods: We included 400 participants who underwent radical sphincter-preserving surgery for rectal cancer between 2005 and 2017. These participants were divided into the DS (+) and DS (-) groups, and the outcomes, including postoperative complications, were compared. Results: The incidence of ileus was higher in the DS (+) group than in the DS (-) group (P<0.01); however, no patients in the DS (+) group showed grade 3 anastomotic leakage. Furthermore, early SRCs were observed in 33 patients (21.6%) and bowel obstruction-related stoma outlet syndrome occurred in 19 patients (12.4%). There was no significant intergroup difference in the incidence of grade 3b postoperative complications. However, the most common reason for reoperation was different in the 2 groups: anastomotic leakage in 91.7% of patients with grade 3b postoperative complications in the DS (-) group, and SRCs in 85.7% of patients with grade 3b postoperative complications in the DS (+) group. Conclusion: Patients with DS showed higher incidence rates of overall postoperative complications, severe postoperative complications (grade 3), and bowel obstruction, including stoma outlet syndrome, than patients without DS. Therefore, it is important to construct an appropriate DS to avoid SRCs and to be more selective in assigning patients for DS construction.

Clinical impact of laparoscopic surgery and adhesion prevention material for prevention of small bowel obstruction.

Aim: Adhesive small bowel obstructions (SBO) are one of the most common complications following abdominal surgery, and they decrease patient quality of life. Since 2000, laparoscopic surgery has been employed with increasing frequency, as has adhesion prevention material (APM). In this study we tried to evaluate whether laparoscopic surgery and APM reduce the incidence of SBO. Methods: In Cohort 1, we included patients who developed SBO and received inpatient treatment between 2015 and 2018. We evaluated the elapsed time between precedent surgery and the onset of SBO, and what kind of surgery most often causes SBO. In Cohort 2, we included patients who underwent digestive surgery between 2012 and 2014 and evaluated SBO incidence within 5 y after the precedent surgery. Results: In all, 2058 patients were included in Cohort 1. Of these, 164 had experienced no precedent surgery. Among patients with a history of abdominal surgery, 29.7% experienced SBO within 1 y after the precedent surgery and 48.1% within 3 y. Altogether, 18798 patients were analyzed in Cohort 2. The incidence of SBO after laparoscopic colorectal surgery was lower than that of open colorectal surgery (P < .001), and laparoscopic gastroduodenal surgery was also lower (P = .02). However, there were no differences between laparoscopic and open surgery for other types of surgery. The use of APM had no effect on SBO incidence in any type of abdominal surgery. Conclusions: Laparoscopic surgery helps to reduce SBO incidence only in colorectal surgery, and possibly in gastroduodenal surgery. APM does not reduce SBO after abdominal surgery.

[A Case Report for Peritoneal Recurrences by Laparoscopic Surgery after Colorectal Cancer Resection].

We report a cases report of colorectal cancer who underwent repeated resection for peritoneal recurrences by laparoscopic surgery. In 2013, a 70-year-old woman diagnosed with an ascending colon cancer underwent laparoscopic right hemicolectomy. The pathological diagnosis was tub2, pT4aN1M0, Stage Ⅲb. Postoperative adjuvant chemotherapy(uracil and tegafur/Leucovorin)was administered. PET-CT performed at 25 months after the surgery because of CEA elevation. It revealed a peritoneal recurrence in the pouch of Douglas. The following peritoneal recurrences were removed by laparoscopic Hartmann's procedure. Chemotherapy(5-fluorouracil/levofolinate/oxaliplatin/bevacizumab)was administered 11 courses and after that chemotherapy(5-fluorouracil/levofolinate/bevacizumab)was administered 6 courses. PET-CT performed 37 months after the second surgery revealed a peritoneal recurrence near the right ovary in the pouch of Douglas. The following peritoneal recurrences was removed. Chemotherapy(tegafur/gimeracil/oteracil/bevacizumab)was administered 11 courses. The long-term survival has been continued for 7 years and 7 months after first operation. It was considered that laparoscopic surgery for peritoneal recurrence in colorectal cancer is contributed to one of the surgical procedures in selected patients.

Strip1 regulates retinal ganglion cell survival by suppressing Jun-mediated apoptosis to promote retinal neural circuit formation.

In the vertebrate retina, an interplay between retinal ganglion cells (RGCs), amacrine (AC), and bipolar (BP) cells establishes a synaptic layer called the inner plexiform layer (IPL). This circuit conveys signals from photoreceptors to visual centers in the brain. However, the molecular mechanisms involved in its development remain poorly understood. Striatin-interacting protein 1 (Strip1) is a core component of the striatin-interacting phosphatases and kinases (STRIPAK) complex, and it has shown emerging roles in embryonic morphogenesis. Here, we uncover the importance of Strip1 in inner retina development. Using zebrafish, we show that loss of Strip1 causes defects in IPL formation. In strip1 mutants, RGCs undergo dramatic cell death shortly after birth. AC and BP cells subsequently invade the degenerating RGC layer, leading to a disorganized IPL. Mechanistically, zebrafish Strip1 interacts with its STRIPAK partner, Striatin 3 (Strn3), and both show overlapping functions in RGC survival. Furthermore, loss of Strip1 or Strn3 leads to activation of the proapoptotic marker, Jun, within RGCs, and Jun knockdown rescues RGC survival in strip1 mutants. In addition to its function in RGC maintenance, Strip1 is required for RGC dendritic patterning, which likely contributes to proper IPL formation. Taken together, we propose that a series of Strip1-mediated regulatory events coordinates inner retinal circuit formation by maintaining RGCs during development, which ensures proper positioning and neurite patterning of inner retinal neurons.

The back of the eye is lined with an intricate tissue known as the retina, which consists of carefully stacked neurons connecting to each other in well-defined 'synaptic' layers. Near the surface, photoreceptors cells detect changes in light levels, before passing this information through the inner plexiform layer to retinal ganglion cells (or RGCs) below. These neurons will then relay the visual signals to the brain. Despite the importance of this inner retinal circuit, little is known about how it is created as an organism develops. As a response, Ahmed et al. sought to identify which genes are essential to establish the inner retinal circuit, and how their absence affects retinal structure. To do this, they introduced random errors in the genetic code of zebrafish and visualised the resulting retinal circuits in these fast-growing, translucent fish. Initial screening studies found fish with mutations in a gene encoding a protein called Strip1 had irregular layering of the inner retina. Further imaging experiments to pinpoint the individual neurons affected showed that in zebrafish without Strip1, RGCs died in the first few days of development. Consequently, other neurons moved into the RGC layer to replace the lost cells, leading to layering defects. Ahmed et al. concluded that Strip1 promotes RGC survival and thereby coordinates proper positioning of neurons in the inner retina. In summary, these findings help to understand how the inner retina is wired; they could also shed light on the way other layered structures are established in the nervous system. Moreover, this study paves the way for future research investigating Strip1 as a potential therapeutic target to slow down the death of RGCs in conditions such as glaucoma.

CHFR-Promoter-Methylation Status Is Predictive of Response to Irinotecan-based Systemic Chemotherapy in Advanced Colorectal Cancer.

BACKGROUND/AIM: We investigated whether promoter methylation of the checkpoint-with-forkhead-and-ring-finger-domains (CHFR) gene is a predictor of the efficacy of irinotecan-based systemic chemotherapy for advanced colorectal cancer (CRC) patients. MATERIALS AND METHODS: CHFR-promoter methylation was measured by quantitative methylation-specific PCR (qMSP). The histoculture drug response assay (HDRA) was used in vitro to analyze the correlation between CHFR-promoter methylation and the efficacy of the irinotecan-active-metabolite SN38 in colorectal-cancer tissues from 44 CRC patients. CHFR promoter-methylation was also analyzed for its correlation with clinical response to irinotecan-based systemic chemotherapy of 49 CRC patients. RESULTS: CHFR-promoter methylation significantly-positively correlated with inhibition of colon cancer by SN38 in the HDRA (p=0.002). CHFR-promoter methylation also significantly-positively correlated with clinical response to irinotecan-based systemic chemotherapy (p=0.04 for disease control). CHFR-promoter methylation also significantly-positively correlated (p=0.01) with increased progression-free survival for patients treated with irinotecan-containing FLOFIRI in combination with bevacizumab, the most-frequent regimen in the cohort. CONCLUSION: Sensitivity of advanced CRC patients to irinotecan-based systemic chemotherapy can be predicted by the extent of CHFR-promoter methylation.

Study of Purse-string Skin Closure Plus Negative-pressure Wound Therapy for Stoma Closure.

Background: Although purse-string skin closure (PSC) is an effective method for stoma closure considering wound infection, the period for scarring will be prolonged. The aim of this study was to assess whether negative-pressure wound therapy (NPWT) can reduce the wound-scarring period for PSC after stoma closure. Methods: Patients who underwent stoma closure between January 2015 and August 2020 at our department were retrospectively assessed. Patients in the control group received only PSC, and patients in the NPWT group received both PSC and NPWT using the VAC® or PICO®. The primary endpoint of this study was the short-term reduction ratio (RR). The RR is calculated by the length, width, and depth of the wound of the stoma closure site. The secondary endpoints were scarring period and wound-related complications such as surgical site infection, dermatitis, bleeding, enterocutaneous fistula, and ventral hernia. Results: Of the 53 patients included in this study, 21 had their stoma closed by PSC and 32 had their stoma closed by PSC plus NPWT. No significant differences were observed in patient characteristics or peri-operative states. The RR in the NPWT group was significantly smaller than that in the PSC group at 7 postoperative days (p=0.04). There was no difference in scarring period between the two groups (p=0.11).The rates of postoperative wound-related complications were similar in the two groups (control group: 4 (19%), NPWT group: 7 (21.9%), p=1.0). Conclusions: Our study suggests that PSC plus NPWT might be more effective for wound healing after stoma closure than only PSC.

Application of the Bioabsorbable Polyglycolic Acid Sheet in Colorectal Anastomosis in Animal Models.

Objectives: Anastomotic complications after colorectal surgery are one of the most serious outcomes. To address this issue, this study used the newly developed bioabsorbable polyglycolic acid (PGA) sheet to assess its usefulness and safety using two approaches of double stapling technique (DST) after laparoscopic anterior resection (AR) in pig models. Methods: Rectal intratissue pressure was assessed after DST anastomosis in two groups, i.e., with (PGA group) or without PGA sheet (nonPGA group), which was sandwiched between the anastomosis in the first approach. In the second approach, after laparoscopic DST anastomosis with PGA sheet attached at anvil side, the clinical short-term outcomes within 1 week and histological findings at 1 week after the surgery were evaluated. Results: Assessment of rectal intratissue pressure showed a mean pressure of 9.28 kPa in the PGA group versus 5.78 kPa in the nonPGA group (p = 0.39). The results of clinical short-term outcomes revealed that there were no anastomotic complications. The results of histological findings in anastomotic bowel tissues with PGA sheet were not significantly different from those of the control case. Conclusions: The bioabsorbable PGA sheet can be used for colorectal DST anastomosis in animal models and may be a valuable tool for this procedure.

A case of simultaneous abdominal wall metastasis of hepatocellular carcinoma with long-term relapse-free survival after laparoscopic resection.

We report our experience of an extremely rare case of a simultaneous extrahepatic metastasis of hepatocellular carcinoma (HCC) with long-term relapse-free survival, treated by laparoscopic resection of an abdominal wall tumor and subsequent radiofrequency ablation (RFA) of an intrahepatic lesion. A 76-year-old man visited a local clinic for right lower abdominal pain. He was treated with antibiotics and the symptom resolved. However, a mass was detected in the same region and he was referred to our hospital for further evaluation. Computed tomography (CT) of the abdomen showed a mass 5 cm in diameter, raising suspicions of an intra-abdominal tumor. Laparoscopic surgery was performed, and the tumor was found in the abdominal wall and completely resected. Histopathological examination yielded a diagnosis of extrahepatic HCC. Post-operative positron emission tomography (PET)-CT showed increased uptake of fluorodeoxyglucose in segment 3 (S3) of the liver. On performing a liver biopsy, HCC was diagnosed. Subsequently, the S3 lesion was treated with radiofrequency ablation. The patient has remained relapse-free for 6 years without further treatments.

Analysis of ileostomy stool samples reveals dysbiosis in patients with high-output stomas.

Construction of a diverting stoma can significantly reduce the onset of severe anastomotic leakage in patients with rectal cancer. High-output stoma is one of the most important potential surgical complications after anal function-preserving surgery with ileostomy. Culture-independent techniques have revealed the interaction of the complex intestinal bacterial ecology with various diseases. Our objective was to evaluate the differences in patient characteristics and gut microbiota distribution features in patients with high-output stomas. The cases of 24 consecutive patients who underwent curative resection for rectal cancer at our hospital between November 2016 and June 2018 were reviewed, and the patients were categorized into high-output and low-output groups. Their microbiota were analyzed using next-generation sequencing of ileostomy stool samples collected on postoperative day 7. There was a significant difference in the percentage of Bacteroidetes between the high-output and low-output groups (14.8% vs 0.5%; p=0.01). The percentage of Clostridium butyricum was increased in the low-output group (p=0.01). After the exclusion of those treated with the probiotic Miya-BM, whose principal component is C. butyricum, analyses revealed no significant differences between the high-output and low-output groups. This pilot study provides the first evidence correlating gut microbiota with the pathogenesis of high- output stoma compared with low-output stoma.

Laparoscopic Surgery Is Acceptable for Elderly Patients With Colorectal Cancer: A Propensity Score-matched Study.

BACKGROUND/AIM: The study was performed to examine the suitability of laparoscopic surgery for elderly patients with colorectal cancer. PATIENTS AND METHODS: The subjects were 242 patients aged ≥80 years who underwent primary tumor resection of colorectal cancer using laparoscopic assisted colectomy (LAC, n=145) or open colectomy (OC, n=97). Propensity score matching used to balance the characteristics of the groups resulted in 76 patients being assigned to each group. RESULTS: Before matching, Glasgow Prognostic Score (GPS), American Society of Anesthesiologists physical status (ASA-PS), and previous abdominal surgery differed significantly between the groups (p<0.05), but after matching, all covariates were balanced (p≥0.05). Short-term outcomes were better after LAC (p<0.05), including fewer postoperative complications and less delirium. Regarding long-term outcomes, 5-year overall survival did not differ significantly between the groups (p=0.91). CONCLUSION: In elderly patients with colorectal cancer, short-term results are better after LAC than OC and long-term results are similar. These findings indicate that LAC is acceptable in this patient population.

Rectal metastasis from bladder urothelial carcinoma: a case report.

BACKGROUND: Urothelial carcinoma arises from transitional cells in the urothelial tract. In advanced cases, it can metastasize locally to surrounding organs or distally to organs such as the lungs, bones, or liver. Here we describe a case of rectal metastasis from urothelial carcinoma treated with multiple sessions of transurethral resection of bladder tumor (TURBT). CASE PRESENTATION: A 72-year-old woman presented to our department with abdominal bloating andobstructed defecation. She had undergone two sessions of TURBT for early urothelial carcinoma in another hospital at 64 and 65 months ago, respectively. Cystoscopy at 3 months after the second TURBT session had indicated disease recurrence, and thus, she had been referred to our hospital for further examination, followed by TURBT for the third time at 59 months ago and for the fourth time at 48 months ago; thereafter, she had been followed up with cystoscopy every 6 months without any recurrence. However, she returned to our hospital, complaining of difficult defecation. Subsequent colonoscopy demonstrated an obstructive tumor in the rectum, which was pathologically diagnosed as metastatic urothelial carcinoma of the bladder. Laparoscopic examination revealed two small areas of peritoneal dissemination in the pelvis. A sigmoid colostomy was performed without rectal tumor resection. She has been receiving chemotherapy and is still alive 10 months after surgery. CONCLUSIONS: Rectal metastasis is a rare site of metastasis for urothelial carcinomas. It is important to consider the possibility of annular rectal constriction caused by infiltrating or metastasizing urothelial carcinoma when managing patients with urothelial carcinoma and with difficult defecation.

Significance of postoperative adjuvant chemotherapy with an oxaliplatin-based regimen after simultaneous curative resection for colorectal cancer and synchronous colorectal liver metastasis: a propensity score matching analysis.

BACKGROUND: Expansion of the indication for liver resection and new regimens for systemic chemotherapy have improved postoperative outcomes for synchronous colorectal liver metastases (CRLM). However, such cases can still have a high recurrence rate, even after curative resection. Therefore, there is a need for postoperative adjuvant chemotherapy (POAC) after liver resection in patients with CRLM. There are few studies of the efficacy of POAC with an oxaliplatin-based regimen after simultaneous resection for colorectal cancer and CRLM with curative intent. The goal of the study was to compare POAC with oxaliplatin-based and fluoropyrimidine regimens using propensity score (PS) matching analysis. METHODS: The subjects were 94 patients who received POAC after simultaneous resection for colorectal cancer and synchronous CRLM, and were enrolled retrospectively. The patients were placed in a L-OHP (+) group (POAC with an oxaliplatin-based regimen, n = 47) and a L-OHP (-) group (POAC with a fluoropyrimidine regimen, n = 47). Recurrence-free (RFS), cancer-specific (CSS), unresectable recurrence-free (URRFS), remnant liver recurrence-free (RLRFS), and extrahepatic recurrence-free (EHRFS) survival were analyzed. RESULTS: Before PS matching, the L-OHP (+) and (-) groups had no significant differences in RFS, CSS, URRFS, RLRFS, and EHRFS. Univariate analysis indicated significant differences in age, preoperative serum CEA (≤ 30.0 ng/mL/ > 30.0 ng/mL), differentiation of primary tumor (differentiated/undifferentiated), T classification (T1-3/T4), number of hepatic lesions and maximum diameter of the hepatic lesion between the L-OHP (+) and (-) groups. After PS matching using these confounders, RFS was significantly better among patients in the L-OHP (+) group compared with the L-OHP (-) group (HR 0.40, 95% CI 0.17-0.96, p = 0.04). In addition, there was a trend towards better RLRFS among patients in the L-OHP (+) group compared with the L-OHP (-) group (HR 0.42, 95% CI 0.17-1.02, p = 0.055). However, there were no significant differences in CSS, URRFS and EHRFS between the L-OHP (+) and (-) groups. CONCLUSIONS: PS matching analysis demonstrated the efficacy of POAC with an oxaliplatin-based regimen in RFS and RLRFS.