Coexistence of Colorectal Cancer and Immunoglobulin G4-Related Disease in the Same Lesion: A Rare Case with Molecular Classification.

Immunoglobulin G4-related disease (IgG4-RD) is a novel fibroinflammatory disorder characterized by enlargement of the involved organs, elevated IgG4 levels, and abundant infiltration of IgG4-positive plasma cells. Indeed, primary colon cancers arising from IgG4-RD are rare. This case report describes a rare occurrence of simultaneous colorectal cancer and IgG4-RD in the same lesion in a 62-year-old male patient. The patient underwent a right hemicolectomy under the suspicion of primary colon cancer. The mass was grossly well-defined and yellowish tan, and the background colon was fibrotic. Microscopically, the tumor cells showed glandular differentiation characteristic of adenocarcinoma in a background of dense lymphoplasmacytic infiltration with fibrosis and obliterative phlebitis in the pericolic fat tissue. IgG4 immunohistochemical staining showed diffuse positivity in infiltrating plasma cells. The patient was administered adjuvant chemotherapy and prednisolone therapy. The patient's serum IgG4 levels gradually decreased, and a follow-up positron emission tomography-computed tomography scan 1 year after surgery showed no evidence of local or distant recurrence of colorectal cancer. IgG4-RD occurring concurrently with primary colon adenocarcinoma has not been reported. Increased awareness of this rare coexistence can guide clinicians in navigating diagnostic complexities and selecting optimal therapeutic strategies.

Precision endoscopy in the era of climate change and sustainability.

Global warming caused by increased greenhouse gas (GHG) emissions has a direct impact on human health. Gastrointestinal (GI) endoscopy contributes significantly to GHG emissions due to energy consumption, reprocessing of endoscopes and accessories, production of equipment, safe disposal of biohazardous waste, and travel by patients. Moreover, GHGs are also generated in histopathology through tissue processing and the production of biopsy specimen bottles. The reduction in unnecessary surveillance endoscopies and biopsies is a practical approach to decrease GHG emissions without affecting disease outcomes. This narrative review explores the role of precision medicine in GI endoscopy, such as image-enhanced endoscopy and artificial intelligence, with a focus on decreasing unnecessary endoscopic procedures and biopsies in the surveillance and diagnosis of premalignant lesions in the esophagus, stomach, and colon. This review offers strategies to minimize unnecessary endoscopic procedures and biopsies, decrease GHG emissions, and maintain high-quality patient care, thereby contributing to sustainable healthcare practices.

Response Prediction after Neoadjuvant Chemotherapy for Colon Cancer Using CT Tumor Regression Grade: A Preliminary Study.

Purpose: To investigate whether CT-based tumor regression grade (ctTRG) can be used to predict the response to neoadjuvant chemotherapy (NAC) in colon cancer. Materials and Methods: A total of 53 patients were enrolled. Two radiologists independently assessed the ctTRG using the length, thickness, layer pattern, and luminal and extraluminal appearance of the tumor. Changes in tumor volume were also analyzed using the 3D Slicer software. We evaluated the association between pathologic TRG (pTRG) and ctTRG. Patients with Rödel's TRG of 2, 3, or 4 were classified as responders. In terms of predicting responder and pathologic complete remission (pCR), receiver operating characteristic was compared between ctTRG and tumor volume change. Results: There was a moderate correlation between ctTRG and pTRG (ρ = -0.540, p < 0.001), and the interobserver agreement was substantial (weighted κ = 0.672). In the prediction of responder, there was no significant difference between ctTRG and volumetry (Az = 0.749, criterion: ctTRG ≤ 3 for ctTRG, Az = 0.794, criterion: ≤ -27.1% for volume, p = 0.53). Moreover, there was no significant difference between the two methods in predicting pCR (p = 0.447). Conclusion: ctTRG might predict the response to NAC in colon cancer. The diagnostic performance of ctTRG was comparable to that of CT volumetry.

Streptococcus Mitis Endocarditis Associated with Early Gastric Carcinoma.

We report a case of Streptococcus mitis endocarditis associated with early gastric carcinoma. A 71-year-old man who had been diagnosed with aortic regurgitation (AR) two years previously was referred for valve surgery and evaluation of elevated inflammatory markers. Four months previously, atrophic gastritis, early gastric adenocarcinoma, and colon polyp had been identified in the patient during endoscopy. However, Helicobacter pylori testing was negative. On admission, he had no dental diseases or recent oral procedures. Echocardiography demonstrated severe AR and mobile vegetation on the aortic valve. Magnetic resonance imaging revealed cerebral embolism and spondylodiscitis. Blood cultures grew Streptococcus mitis. At surgery, destruction of the left cusp with vegetation and a perforation of the non-coronary cusp were found; in addition, aortic valve replacement was performed. Although the association between Streptococcus bovis bacteremia and colon neoplasm is well recognized, the association between Streptococcus mitis endocarditis and gastrointestinal carcinoma should also be kept in mind.

A Review of Community Awareness for Colorectal Cancer Screening and Prevention in North and Central Asian Countries.

OBJECTIVES: Colorectal cancer (CRC) incidence and mortality rates are increasing in low- and middle-income countries (LMIC), including North and Central Asian countries (NCAC). Screening and risk factor reduction can aid in the prevention of colorectal cancer, but communities lack awareness of these screening programs. The review assessed community awareness about CRC screening and prevention in NCAC to facilitate cancer control policies. Study type and methods: For this scoping review, we searched PubMed/Medline, Embase, and the Cochrane Library for articles on community awareness about CRC screening and prevention in NCAC according to inclusion and exclusion criteria. RESULTS: Eight of 677 articles from five of the 15 NCAC countries met the criteria. Most of the studies utilized a survey design. The results indicated low awareness of the availability of CRC screening and poor knowledge of CRC symptoms. Knowledge of CRC screening modalities was also inadequate. Some countries also lack CRC screening programs. CONCLUSION: Community unawareness is a significant barrier to screening program utilization and sustenance. Community health awareness programs (CHAP) are needed to improve the uptake of CRC screening in NCAC. The NCAC should include CHAP as an integral component of the CRC control plan. Long-term cancer control in LMIC could be adapted using the step-ladder pyramidal approach.

Incidentally Discovered Mucosal Prolapse of the Colon During Colorectal Cancer Screening: A Case Report.

Colonic mucosal prolapse syndrome is a rare type of non-neoplastic non-inflammatory colorectal polyps that can mimic neoplastic lesions. We present a case of a 65-year-old man with mucosal prolapse syndrome, incidentally, discovered during colorectal cancer screening. The patient was asymptomatic, and his physical exam and laboratory test results were unremarkable. During a colonoscopy, the physician removed three small tubular adenomas and two pedunculated polyps suspicious of neoplasms. Retroflexion revealed small internal hemorrhoids. The histology of the larger polyps revealed mucosal prolapse features, while the smaller polyps displayed features consistent with tubular adenomas. Management involves the removal of associated polyps during colonoscopy, followed by surveillance colonoscopy to detect any recurrent polyps or early signs of colorectal cancer. Accurate diagnosis is crucial to avoid unnecessary interventions and ensure appropriate management.

Aplicación de reconstrucción 3D e inteligencia artificial a la escisión completa de mesocolon y linfadenectomía D3 en el cáncer de colon / Application of 3D-reconstruction and artificial intelligence for complete mesocolic excision and D3 lymphadenectomy in colon cancer

Las técnicas de reconstrucción 3D basadas en algoritmos matemáticos y la inteligencia artificial son una línea de innovación actual en cirugía oncológica colorrectal. El objetivo de este estudio es mostrar la experiencia inicial de un sistema de procesamiento de imagen y reconstrucción 3D en la planificación de escisión completa de mesocolon y linfadenectomía D3 en cáncer de colon. Se aplica en un caso de neoplasia de ángulo esplénico, así como en neoplasia de colon derecho con sospecha de infiltración retroperitoneal. Se empleó el procesamiento de imagen y reconstrucción 3D para delimitar un margen intestinal de 10cm proximal y distal al tumor y delimitar la vascularización correspondiente a la tumoración. En el cáncer de colon derecho se mostró la posición y dimensiones exactas del área de linfadenectomía D3 y posible infiltración de la fascia retroperitoneal. El procesamiento de imagen y reconstrucción 3D permite obtener información valiosa a partir de la tomografía computarizada. Esta podría emplearse en la estrategia quirúrgica y así mejorar los resultados oncológicos y disminuir las complicaciones intraoperatorias. (AU)

Mathematical algorithms 3D-reconstruction techniques and artificial intelligence are a current line of innovation in colorectal surgical oncology. The objective of this study is to show the initial experience of a 3D image processing and reconstruction system to perform complete mesocolic excision and D3-lymphadenectomy in colon cancer. It is applied to a splenic flexure neoplasm and in a right colon cancer with suspected retroperitoneal infiltration. 3D image processing and reconstruction was employed to delimit 10cm proximal and distal intestinal margins to the tumor and define its corresponding vascularization. In right colon cancer it showed position and exact dimensions of D3-lymphadenectomy area and possible retroperitoneal fascia infiltration. 3D image processing and reconstruction allows to obtain valuable information from computerized tomography scan. It could be employed during surgical strategy planification to improve oncological results and reduce intraoperative complications. (AU)

Penis metastasis in colon cancer: A case report of an unusual site of dissemination.

INTRODUCTION AND IMPORTANCE: Colorectal cancer is a leading cause of cancer-related deaths worldwide. It is estimated that approximately 1.93 million new cases of colorectal cancer were diagnosed and almost one million global colorectal cancer-caused deaths in 2020. The incidence of colorectal cancer has been dramatically rising at alarming rates worldwide in the last decades. The most often sites of metastases are lymph nodes, liver, lung, and peritoneum. CASE PRESENTATION: We present a rare case of a 63-year-old male patient presenting with a nodule in the penis after being treated for cancer in the hepatic flexure of the colon. Biopsy showed colorectal cancer recurrence in the penis. CLINICAL DISCUSSION: Metastasis from colorectal cancer to the penis is rare and poorly discussed, with scarce data in the literature. CONCLUSION: A high level of suspicion should be adopted for the correct diagnosis and early treatment.

Application of 3D-reconstruction and artificial intelligence for complete mesocolic excision and D3 lymphadenectomy in colon cancer.

Mathematical algorithms 3D-reconstruction techniques and artificial intelligence are a current line of innovation in colorectal surgical oncology. The objective of this study is to show the initial experience of a 3D image processing and reconstruction system to perform complete mesocolic excision and D3-lymphadenectomy in colon cancer. It is applied to a splenic flexure neoplasm and in a right colon cancer with suspected retroperitoneal infiltration. 3D image processing and reconstruction was employed to delimit 10 cm proximal and distal intestinal margins to the tumor and define its corresponding vascularization. In right colon cancer it showed position and exact dimensions of D3-lymphadenectomy area and possible retroperitoneal fascia infiltration. 3D image processing and reconstruction allows to obtain valuable information from computerized tomography scan. It could be employed during surgical strategy planification to improve oncological results and reduce intraoperative complications.

Prognosis of patients with unresectable stage IV Colon cancer undergoing primary tumor resection: A multicenter study of minimally symptomatic or asymptomatic primary tumor.

AIM: To determine the factors affecting survival of patients with unresectable stage IV colon cancer with Primary tumour resection (PTR) as first treatment compared with those with conventional palliative chemotherapy. METHODOLOGY: Patient with minimally or asymptomatic stage IV colon cancer at diagnosis were identified from prospectively managed database in included centers from 2015 to 2020. Patient with and without PTR performed were followed up. Primary end point was overall survival. Risk factors affecting survival will be analysis by Kaplan Meier statistics and Cox regression analysis. Secondary outcome will be stoma formation, complication rate and reoperation. RESULTS: 162 patients were included in analysis. 68 patients treated with systemic therapy PTR and 94 patients with tumour in-situ before systemic therapy. Baseline demographics including sex, age, functional status, tumour location, site of metastasis, RAS status were similar except there was slightly more liver metastasis on non-resection group (63.2% vs 79.8%). Cox regression analysis found PTR (HR 0.485, 0.302-0.778, p = 0.003)), bone metastasis (HR 3.163, 1.146-6.918, p = 0.004) commencement (HR 0.579, 0.345-0.971, p = 0.038) and completion of systemic therapy (HR 0.310, 0.178-0.539, p = 0.000) are independent factors predicting survival. The median overall survival after PTR vs tumour in-situ is 28 (IQR: 16-47) vs 12 (IQR:6-31) months (p<0.001). CONCLUSION: Resection of primary tumour is an independent good prognostic factor in relatively asymptomatic stage IV CA colon patients with unresectable metastasis. Resection should be considered as long as the procedure is straight forward and do not impose significant morbidities with careful patient selection.

Randomized controlled trial of EndoRings assisted colonoscopy versus standard colonoscopy.

OBJECTIVES: The EndoRings device is a distal attachment consisting of two layers of circular flexible rings that evert mucosal folds. The aim of this study was to investigate whether EndoRing assisted colonoscopy (ER) improves polyp and adenoma detection compared to standard colonoscopy (SC). METHODS: Multicenter, parallel group, randomized controlled trial. RESULTS: Total of 556 patients randomized to ER (n = 275) or SC (n = 281). Colonoscopy completed in 532/556 (96%) cases. EndoRings removed in 74/275 (27%) patients. Total number of polyps in ER limb 582 vs. 515 in SC limb, P = 0.04. Total number of adenomas in ER limb 361 vs. 343 for SC limb, P = 0.49. A statistically significant difference in the mean number of polyps per patient in both the intention to treat (1.84 SC vs. 2.10 ER, P = 0.027) and per protocol (PP) (1.84 SC vs. 2.25 ER, P = 0.004). CONCLUSIONS: Our study shows promise for the EndoRings device to improve polyp detection.

Clinicopathological features and prognosis of colonic and rectal gastrointestinal stromal tumors: A propensity score matching analysis.

Background: Colonic gastrointestinal stromal tumor (cGIST) and rectal gastrointestinal stromal tumor (rGIST) are two rare subtypes of gastrointestinal stromal tumor (GIST). The view that colonic and rectal carcinoma are different is generally accepted; however, whether there is a difference between cGIST and rGIST is still unknown. Here, we aimed to provide evidence for future clinical management and research by comparing the differences between the two types of GIST in the above-mentioned aspects. Methods: Patients were enrolled from three medical centers in China and published literature was collected following the inclusion and exclusion criteria. Propensity score matching was used to eliminate differences between cohorts. Results: Between cGIST and rGIST patients, significant differences were observed in age, tumor size, mitotic index, NIH risk category, growth pattern, and symptoms. Adjuvant therapy is used in a high proportion of cGIST patients, and neoadjuvant therapy is used in a high proportion of rGIST patients. Although local resection is the main surgical method in both cohorts, the proportion is higher in cGIST patients. The overall survival of rGIST patients was better than that of the cGIST patients before propensity score matching (PSM). Interestingly, no significant differences in prognosis were observed after PSM. Conclusions: Although there were significant differences between cGIST and rGIST patients in baseline characteristics, clinicopathological features, treatment choice, and overall survival rate before PSM, no significant differences in long-term survival were observed between the two groups after PSM. In our study, there may be no differences in the tumor entity between cGIST and rGIST.

Endoscopic Stenting for Malignant Left-Sided Large-Bowel Obstruction in Patients with Colorectal Cancer: Evaluation according to Pathological Stage.

INTRODUCTION: Self-expandable metallic stents (SEMSs) are widely used in patients with malignant left-sided large-bowel obstruction (MLLO) to convert an emergency situation into an elective one. However, the effects of endoscopic stenting on oncological outcomes remain unclear. This study aimed to analyze the oncological outcomes of SEMS placement in patients with MLLO stratified by pathological stage. METHODS: We reviewed the data of patients with MLLO that were prospectively collected between January 2005 and December 2016. Patients were divided into those who underwent SEMS placement as a bridge to surgery and those who underwent emergency surgery. Disease-free survival (DFS) and overall survival (OS) were compared between groups, and their prognostic factors were determined by pathological stage. RESULTS: SEMS placement and emergency surgery were performed in 130 and 45 patients, respectively. There was no difference in the 5-year DFS and OS rate between two groups. Subgroup analysis revealed a significant difference in the 5-year DFS and OS rate in patients with stage III MLLO, but was not observed in patients with stage II MLLO. Multivariate Cox regression analysis for stage III MLLO revealed endoscopic stenting (hazard ratio [HR], 2.051; 95% confidence interval [CI], 1.018-4.131; p = 0.044) as the only prognostic factor for DFS. Age, tumor differentiation, perineural invasion, and endoscopic stenting (HR, 3.189; 95% CI, 1.346-7.556; p = 0.008) were prognostic factors for OS. CONCLUSION: In terms of oncologic outcomes, endoscopic stenting might be more beneficial than ES in patients with stage III MLLO.

Prolonged postoperative length of stay may be a valuable marker for susceptibility to relapse beyond established risk factors in patients with stage III colon cancer.

BACKGROUND: Delay from surgery to adjuvant chemotherapy causes impaired survival among patients undergoing radical resection for stage III colon cancer, and the underlying mechanism for this is incompletely clarified. It is established that prolonged postoperative hospital length of stay (LOS) is associated with delayed initiation of the adjuvant treatment driving the assumption that prolonged LOS is prognostically unfavorable due to this fact and case mix factors. We hypothesize that prolonged LOS after surgery is a valuable marker for susceptibility to relapse that is not detected in established prognostic factors and, alone, associated with a shorter disease-free survival (DFS). MATERIALS AND METHODS: A total of 690 consecutive patients undergoing elective radical resection for stage III colon cancer in 2000-2015 were identified in a prospective detailed facility database. Univariate and multivariate analyses were performed using Cox proportional hazards model in the evaluation of LOS as an independent prognostic factor. RESULTS: Short postoperative LOS, low comorbidity, and few complications were associated with longer DFS (p < 0.01). Fewer patients in the short and intermediate LOS groups had a relapse in their disease (28% and 33%, respectively), compared to the patients with longer LOS (40%, p < 0.05). LOS was a prognostic factor for DFS in the unadjusted univariate model (HR 1.04 per unit change) and remained statistically significant in the adjusted multivariate analysis, with a HR of 1.03 per hospital day (p < 0.01). CONCLUSIONS: Postoperative LOS independently correlates with the risk of recurrence and DFS, regardless of if adjuvant chemotherapy is given, along with the factors such as age, comorbidity, complications, and tumor features. We propose a further investigation into the causal mechanisms based on tumor and host biology linking LOS to DFS beyond established risk factors.

Multifocal diffuse large cell neuroendocrine carcinoma of the colon.

Background: Large cell neuroendocrine carcinomas (LCNEC) of the colon are an extremely rare and aggressive type of colorectal cancer. While multifocality is more frequently seen in small intestine NECs, no cases of multifocal NEC of the colon have been reported before. Aim: A 69-year-old male patient presented with abdominal pain. Colonoscopy revealed a necrotic-polypoid mass in the sigmoid colon and the biopsy result was reported as malignant epithelial tumor. Laparoscopic anterior resection was performed with the preliminary diagnosis of colon adenocarcinoma. Histopathological examination revealed three polypoid tumors, the largest of which was 4 cm, in the sigmoid colon. Immunohistochemical examination showed positivity for synaptophysin, chromogranin, and CDX2. High Ki67 proliferation index, high mitosis, and widespread p53 expression were observed in all tumors. With these findings, a diagnosis of multifocal large cell NEC was made. To the best of our knowledge, this is the first report describing a case of multifocal large cell NEC of the colon. Relevance for Patients: LCNECs of the colon are very aggressive. Here, we report for the first time a case of multifocal LCNEC. In a short period of 1 month after the surgery, new widespread metastases were detected in the liver. Therefore, these tumors should be followed more closely than usual for early treatment.

Streptococcus gallolyticus bacteremia detected in apheresis platelets and its link to colonic neoplasms

Introduction: Streptococcus gallolyticus belongs to theStreptococcus bovis complex, and it is a common bacterium colonizing the gastrointestinal tract. Its presence in the blood may suggest an underlying pathology such as a colonic neoplasm. We report herein a case of S. bovis bacteremia in an apheresis platelet donor, review similar cases in the literature, and suggest a flowchart for the management of similar cases in other blood donation centers. Case Presentation: A 61-year-old subject presented to a Hemotherapy Service to make an apheresis platelet donation. On quality control testing, S. gallolyticus was identified in hemoculture, and the donor was called back for follow-up. At first, a new hemoculture was requested, and the patient was referred to the outpatient department of infectious diseases to further investigate pathologies associated with S. gallolyticus. A subsequent colonoscopy investigation evidenced a polypoid structure in the ascending colon. Pathology reported the resected specimen as a low-grade tubular adenoma. Conclusion: Isolation of S. bovis in blood products requires further investigation and should be managed with precision by Hemotherapy Services. A standard protocol for the management of asymptomatic patients with S. bovis positive hemoculture, with the requests of a new blood culture, a colonoscopy, and an echocardiogram is crucial, as it may ensure early diagnosis and reduce morbidity and mortality. (AU)

Over-the-catheter endoscope replacement for stenting in patients with inaccessible malignant colonic obstruction with coexisting peritoneal carcinomatosis.

Although a large-caliber endoscope (LCE) is indispensable for through-the-scope placement of a self-expandable metallic stent (SEMS) in patients with malignant colonic obstruction (MCO), inaccessibility of the target obstructing lesion (TOL) by the endoscope is a significant cause of unsuccessful procedures. We herein present a novel salvage procedure when the TOL is not directly accessible by an LCE in conditions such as coexisting peritoneal carcinomatosis involving the colon. The salvage procedure, termed over-the-catheter endoscope replacement (OCER), starts with an ultraslim endoscope suitable for deep insertion beyond a tortuous colon for traversing a guidewire through the TOL. The ultraslim endoscope is then withdrawn and replaced by an LCE through the following steps. An endoscopic retrograde cholangiopancreatography catheter is preloaded in the LCE, the catheter alone is passed over the guidewire already traversed through the TOL, and the LCE is navigated over the catheter as far as possible toward the TOL to deliver the SEMS delivery system in a standard through-the-scope manner or further in an over-the-wire manner even if LCE insertion is incomplete. Among the 165 patients with MCO who underwent stenting during our study period, OCER led to successful procedures in all nine patients whose TOLs were initially inaccessible because of colon-involving peritoneal carcinomatosis. By utilizing the functions of distinctive endoscopes in a unique and complementary way, OCER can be a practical salvage option for challenging cases of MCO that are highly prone to unsuccessful palliation by conventional SEMS placement.

Single plus one-port robotic surgery using the da Vinci Single-Site Platform versus conventional multi-port laparoscopic surgery for left-sided colon cancer.

INTRODUCTION: Recently, single plus one-port robotic surgery (SPORS) was introduced to overcome the limitations of single-port laparoscopic surgery for the treatment of various diseases. AIM: To compare the clinical and cosmetic outcomes of SPORS with those of multi-port laparoscopic surgery (MPLS), which is presently the standard surgical treatment for colon cancer. MATERIAL AND METHODS: The study included 36 patients who underwent SPORS and 61 patients who underwent MPLS for left-sided colon cancer between August 2014 and January 2016. The Patient Scar Assessment Questionnaire (PSAQ) was used to assess cosmetic outcomes. RESULTS: SPORS involved a longer median operative time than MPLS (232 vs. 155 min, p = 0.009). There were no apparent differences in the time before diet tolerance, length of hospital stay, postoperative pain score, and postoperative complication rate. However, SPORS patients had a shorter total incision length (5.0 vs. 8.0 cm, p < 0.001). The median proximal and distal resection margins and the median number of harvested lymph nodes were comparable between the two groups. The PSAQ favored the SPORS approach, revealing significant differences in appearance (15 vs. 18, p < 0.001), consciousness (9 vs. 11, p < 0.001), satisfaction with appearance (14 vs. 17, p < 0.001), satisfaction with symptoms (9 vs. 10, p = 0.022), and overall score (47 vs. 55, p < 0.001). CONCLUSIONS: The clinicopathologic outcomes of SPORS were comparable but its cosmetic outcomes were superior to those of MPLS for left-sided colon cancer.

Apurinic/apyrimidinic endonuclease 1 is associated with poor prognosis after curative resection followed by adjuvant chemotherapy in patients with stage III colon cancer.

Purpose: Apurinic/apyrimidinic endonuclease 1 (APE1) is a key enzyme involved in the base excision repair pathway. It also has redox activity and maintains various transcription factors in an active reduced state. APE1 may be associated with chemoresistance. In the present study, we first investigated the expression level of APE1 protein and its correlation with oncologic outcomes of oxaliplatin-based chemotherapy in patients with stage III colon cancer. Further, we investigated the effects of human APE1 siRNA on the sensitivity of oxaliplatin in SNU-C2A colon cancer cells. Methods: Tissue specimens from tumor and normal colon of 33 patients with stage III colon cancer were obtained from 2006 to 2009. The patients received at least eight cycles of oxaliplatin-based chemotherapy. APE1 expression was analyzed by immunohistochemistry and Western blotting using a cultured SNU-C2A cell line. Cell viability and apoptosis were determined by Cell Counting Kit-8 and caspase-3 cleavage using Western blotting. Results: All the colon cancer tissues showed APE1 staining in the nucleus, whereas all the normal colon tissues were negative for APE1 staining in the cytoplasm. The group with a higher expression of APE1 demonstrated poorer prognosis than the group with low expression (P=0.026 for overall survival and P=0.021 for disease-free survival). Treatment with oxaliplatin resulted in a dose-dependent increase in APE1 expression in SNU-C2A cells. APE1 siRNA significantly enhanced oxaliplatin-induced growth inhibition, and also increased oxaliplatin-induced apoptosis in SNU-C2A cells. Conclusion: APE1 could be considered a prognostic factor in colon cancer patients treated with oxaliplatin-based chemotherapy.