IGFL2-AS1, a Long Non-Coding RNA, Is Associated with Radioresistance in Colorectal Cancer.

Precise prediction of radioresistance is an important factor in the treatment of colorectal cancer (CRC). To discover genes that regulate the radioresistance of CRCs, we analyzed an RNA sequencing dataset of patient-originated samples. Among various candidates, IGFL2-AS1, a long non-coding RNA (lncRNA), exhibited an expression pattern that was well correlated with radioresistance. IGFL2-AS1 is known to be highly expressed in various cancers and functions as a competing endogenous RNA. To further investigate the role of IGFL2-AS1 in radioresistance, which has not yet been studied, we assessed the amount of IGFL2-AS1 transcripts in CRC cell lines with varying degrees of radioresistance. This analysis showed that the more radioresistant the cell line, the higher the level of IGFL2-AS1 transcripts-a similar trend was observed in CRC samples. To directly assess the relationship between IGFL2-AS1 and radioresistance, we generated a CRC cell line stably expressing a small hairpin RNA (shRNA) targeting IGFL2-AS1. shRNA-mediated knockdown of IGFL2-AS1 decreased radioresistance and cell migration in vitro, establishing a functional role for IGFL2-AS1 in radioresistance. We also showed that downstream effectors of the AKT pathway played crucial roles. These data suggest that IGFL2-AS1 contributes to the acquisition of radioresistance by regulating the AKT pathway.

Valproic acid protects intestinal organoids against radiation via NOTCH signaling.

Radiotherapy is a leading treatment for various types of cancer. However, exposure to high-dose ionizing radiation causes acute gastrointestinal injury and gastrointestinal syndrome. This has significant implications for human health, and therefore, radioprotection is a major area of research. Radiation induces the loss of intestinal stem cells; hence, the protection of stem cells expressing LGR5 (a marker of intestinal epithelial stem cells) is a key strategy for the prevention of radiation-induced injury. In this study, we identified valproic acid (VPA) as a potent radioprotector using an intestinal organoid culture system. VPA treatment increased the number of LGR5+ stem cells and organoid regeneration after irradiation. N-[N-(3,5-difluorophenacetyl)-l-alanyl]-S-phenylglycine t-butyl ester (DAPT, an inhibitor of NOTCH signaling) blocked the radioprotective effects of VPA, indicating that NOTCH signaling is a likely mechanism underlying the observed effects of VPA. In addition, VPA acted as a radiosensitizer via the inhibition of histone deacetylase (HDAC) in a colorectal cancer organoid. These results demonstrate that VPA exerts strong protective effects on LGR5+ stem cells via NOTCH signaling and that the inhibition of NOTCH signaling reduces these protective effects, providing a basis for the improved management of radiation injury.

Oncological Outcomes After Robotic Proctectomy for Rectal Cancer: Analysis of a Prospective Database.

OBJECTIVE: The aim of this study is to evaluate the oncological outcomes of robotic total mesorectal excision (TME) at an NCI designated cancer center. SUMMARY BACKGROUND DATA: The effectiveness of laparoscopic TME could not be established, but the robotic-assisted approach may hold some promise, with improved visualization and ergonomics for pelvic dissection. Oncological outcome data is presently lacking. METHODS: Patients who underwent total mesorectal excision or tumor-specific mesorectal excision for rectal cancer between April 2009 and April 2016 via a robotic approach were identified from a prospective single-institution database. The circumferential resection margin (CRM), distal resection margin, and TME completeness rates were determined. Kaplan-Meier analysis of disease-free survival and overall survival was performed for all patients treated with curative intent. RESULTS: A total of 276 patients underwent robotic proctectomy during the study period. Robotic surgery was performed initially by 1 surgeon with 3 additional surgeons progressively transitioning from open to robotic during the study period with annual increase in the total number of cases performed robotically. Seven patients had involved circumferential resection margins (2.5%), and there were no positive distal or proximal resection margins. One hundred eighty-six patients had TME quality assessed, and only 1 patient (0.5%) had an incomplete TME. Eighty-three patients were followed up for a minimum of 3 years, with a local recurrence rate of 2.4%, and a distant recurrence rate of 16.9%. Five-year disease-free survival on Kaplan-Meier analysis was 82%, and 5-year overall survival was 87%. CONCLUSIONS: Robotic proctectomy for rectal cancer can be performed with good short and medium term oncological outcomes in selected patients.

Detection of Methylated SEPT9 in Korean Colorectal Cancer Patients: Comparison with Previous Studies.

BACKGROUND: This study aimed to investigate the detection of methylated Septin 9 (mSEPT9) in Korean patients with colorectal cancer (CRC) and compare the results with those of previous studies. METHODS: A total of 127 plasma samples (111 patients with untreated CRC, 5 patients with adenomas, and 11 CRC patients treated with concurrent chemoradiotherapy before surgery) were collected. mSEPT9 was measured qualitatively with the Abbott RealTime ms9 Colorectal Cancer Assay. RESULTS: mSEPT9 was detected in 44 of 111 (39.6%) cases of untreated CRC but was not detected in the adenoma cases. The difference in the sensitivity of mSEPT9 among patients with adenomas and those with each stage of untreated CRC was statistically significant (Dukes' staging, p = 0.002 and TNM staging, p = 0.008). The sensitivity of mSEPT9 for each of the stages (I - IV) of untreated CRC patients were 20.7%, 54.1%, 36.6%, and 75.0%, respectively. The positive mSEPT9 results in untreated CRC patients reverted to negative in 19 of 21 patients (90.5%) after treatment. CONCLUSIONS: Compared to previous studies, the overall sensitivity of mSEPT9 was lower, but similar patterns were found in the sensitivities for each stage. Additionally, mSEPT9 appeared to have potential as a monitoring tool for CRC.

Oncologic Outcomes of Extended Robotic Resection for Rectal Cancer.

BACKGROUND: Surgery for locally advanced rectal cancers beyond the plane of total mesorectal excision (TME) or extramesorectal nodal involvement should include complete resection. This study evaluated the oncologic feasibility and safety of robot-assisted surgery for rectal cancer beyond the TME plane. METHODS: The study analyzed the operative, perioperative, and oncologic outcomes for all patients who underwent robot-assisted extended rectal cancer surgery from April 2009 to February 2015. RESULTS: Of 36 patients, 22 underwent multivisceral en bloc resection, and 18 underwent extramesorectal lymph node (EMRLN) dissection. The median tumor location was 5 cm [interquartile range (IQR), 2.2-9.0 cm] from the anal verge. A total of 32 patients underwent neoadjuvant chemoradiation therapy. The median body mass index of the patients was 26.8 kg/m(2) (IQR, 24.0-31.9 kg/m(2)). Conversion was required for one patient because of inability to tolerate the Trendelenburg position. All the resections were R0, and there were no incomplete TMEs. The vagina and prostate or periprostatic structures were the most commonly resected (n = 13/22), and the lateral pelvic nodes were the most common EMRLNs (n = 16/18). The median numbers of examined mesorectal lymph nodes and EMRLNs were respectively 20 (IQR, 18.0-28.0) and 2.5 (IQR, 1.0-6.0). The median hospital stay was 4 days (IQR, 3.0-5.5 days). Six patients experienced Clavien-Dindo grade 3 complications, the most common of which was deep abscess (n = 5, 13.8 %). The 5-year actuarial local recurrence rate was 3.6 %. CONCLUSIONS: Minimally invasive resection for rectal cancer can be performed with extended lymph node dissection or en bloc multivisceral resection using the surgical robot in selected patients. This technique is feasible and has acceptable morbidity.

Prognostic value of 18F-FDG uptake by regional lymph nodes on pretreatment PET/CT in patients with resectable colorectal cancer.

PURPOSE: We evaluated the ability of pretreatment (18)F-FDG uptake by regional lymph nodes to predict the survival of patients with resectable colorectal cancer. METHODS: The records of 78 patients with AJCC stage III colorectal cancer (pathologically confirmed node-positive disease without evidence of distant metastasis) treated with surgery and adjuvant chemotherapy were retrospectively reviewed. The maximum standardized uptake values of the primary tumor (SUVp) and regional lymph nodes (SUVn) were measured by pretreatment (18)F-FDG PET/CT. The ROC curve analyses and the Cox proportional hazard model were used to analyze whether SUVp, SUVn, and clinicopathologic parameters could predict disease-free survival. RESULTS: Although there were no significant differences between the median SUVp in the event group and that in the non-event group, the median SUVn was significantly higher in the event group (1.7) than in the non-event group (0.8, p = 0.023). Based on the ROC curve analysis, SUVn predicted the event for disease-free survival (AUC = 0.668, p = 0.02) with the optimal criterion, sensitivity, specificity, and accuracy of > 1.2, 71%, 63%, and 65%, respectively. However, SUVp did not predict disease-free survival (AUC = 0.570, p = 0.349). Univariate analysis revealed that SUVn (p = 0.011) and venous invasion (p = 0.016) were associated with disease-free survival, but pathologic N stage was not (p = 0.09). By multivariate analysis, only SUVn > 1.2 independently shortened the disease-free survival (relative risk, 2.97; 95% CI, 1.14-7.74, p = 0.026). CONCLUSION: SUVn before surgery may be a useful prognostic marker in patients with AJCC stage III colorectal cancer.

Stimulatory Anticancer Effect of Resveratrol Mediated by G Protein-Coupled Estrogen Receptor in Colorectal Cancer.

Colorectal cancer (CRC) is one of the most high-risk cancers; however, it has been suggested that estrogen signaling in CRC could have a protective effect. Therefore, we focused on the function of the G protein-coupled estrogen receptor (GPER) among the estrogen receptors in CRC. In this study, we investigated the therapeutic effect of resveratrol via GPER in CRC (RKO and WiDr) cells, CRC cell-derived xenograft models, and organoids (30T and 33T). Resveratrol significantly suppressed cell viability and proliferation in highly GPER-expressing RKO cells compared to that in low GPER-expressing WiDr cells. In xenograft models, resveratrol also delayed tumor growth and exhibited a high survival rate depending on GPER expression in RKO-derived tumors. Furthermore, resveratrol significantly inhibited the viability of organoids with high GPER expression. Additionally, the anticancer effect of resveratrol on CRC showed that resveratrol rapidly responded to GPER, while increasing the expression of p-ERK and Bax and cleaving PARP proteins.

Fisetin induces the upregulation of AKAP12 mRNA and anti-angiogenesis in a patient-derived organoid xenograft model.

Colorectal cancer (CRC) is associated with high incidence and mortality rates. Targeted therapies for CRC cause various adverse effects, necessitating the development of novel approaches to control CRC progression. In this milieu, we investigated the anti-CRC effects of fisetin, a natural plant flavonoid. Cytotoxicity was performed in CRC patient-derived organoids (30 T and 33 T). Fisetin-induced tumor growth was evaluated in a CRC patient-derived organoid xenograft (PDOX) model. RNA sequencing, immunohistochemistry, and western blotting were performed subsequently. Fisetin significantly decreased organoid viability in a dose-dependent manner. In the PDOX model, fisetin significantly delayed tumor growth, showing a decrease in Ki-67 expression and the induction of apoptosis. In tumor tissues, four genes were identified as differentially expressed between the control and fisetin-treated groups. Among these, A-kinase anchoring protein 12 (AKAP12) level was significantly increased by fisetin treatment (fold change > 2, p < 0.05). Notably, fisetin significantly inhibited vascular endothelial growth factor (VEGF) and epithelial cell adhesion molecule (EpCAM) via upregulation of AKAP12. Our results demonstrate the upregulation of AKAP12 mRNA and inhibition of angiogenesis by fisetin as a therapeutic strategy against CRC.

Neuromedin U contributes to radiation resistance in colorectal cancer via YAP/TAZ signaling activation.

Resistance to radiation therapy remains a treatment obstacle for patients with high­risk colorectal cancer. Neuromedin U (NMU) has been identified as a potential predictor of the response to radiation therapy by RNA sequencing analysis of colorectal cancer tissues obtained from patients. However, the role of NMU in colorectal cancer remains unknown. In order to investigate role of NMU in colorectal cancer, NMU expression was regulated using small interfering RNA or an NMU­expression pCMV3 vector, and cell counting, wound­healing and clonogenic assays were subsequently performed. NMU knockdown decreased colorectal cancer cell proliferation and migration, and sensitized the cells to radiation. Conversely, NMU overexpression increased radiation resistance, proliferation and migration of colorectal cancer cells. Furthermore, by western blotting and nuclear fractionation experiments, NMU knockdown inhibited the nuclear translocation of yes­associated protein (YAP) and transcriptional co­activator with PDZ­binding motif (TAZ), resulting from the phosphorylation of these proteins. By contrast, the nuclear translocation of YAP and TAZ was increased following NMU overexpression in colorectal cancer cells. Recombinant NMU regulated YAP and TAZ activity, and the expression of the YAP and TAZ transcriptional target genes AXL, connective tissue growth factor and cysteine­rich angiogenic inducer 61 in an NMU receptor 1 activity­dependent manner. These results suggested that NMU may contribute to the acquisition of radioresistance in colorectal cancer by enhancing the Hippo signaling pathway via YAP and TAZ activation.

Prediction of Neoadjuvant Chemoradiotherapy Response in Rectal Cancer Patients Using Harmonized Radiomics of Multcenter 18F-FDG-PET Image.

We developed machine and deep learning models to predict chemoradiotherapy in rectal cancer using 18F-FDG PET images and harmonized image features extracted from 18F-FDG PET/CT images. Patients diagnosed with pathologic T-stage III rectal cancer with a tumor size > 2 cm were treated with neoadjuvant chemoradiotherapy. Patients with rectal cancer were divided into an internal dataset (n = 116) and an external dataset obtained from a separate institution (n = 40), which were used in the model. AUC was calculated to select image features associated with radiochemotherapy response. In the external test, the machine-learning signature extracted from 18F-FDG PET image features achieved the highest accuracy and AUC value of 0.875 and 0.896. The harmonized first-order radiomics model had a higher efficiency with accuracy and an AUC of 0.771 than the second-order model in the external test. The deep learning model using the balanced dataset showed an accuracy of 0.867 in the internal test but an accuracy of 0.557 in the external test. Deep-learning models using 18F-FDG PET images must be harmonized to demonstrate reproducibility with external data. Harmonized 18F-FDG PET image features as an element of machine learning could help predict chemoradiotherapy responses in external tests with reproducibility.

High dose stereotactic body radiotherapy using three fractions for colorectal oligometastases.

BACKGROUND AND OBJECTIVES: This study evaluated the treatment result of high dose stereotactic body radiation therapy (SBRT) for colorectal oligometastases. METHODS: Between 2003 and 2009, 41 patients with 50 lesions confined to one organ from colorectal cancer (CRC) and treated with high dose SBRT ≥45 Gy were retrospectively reviewed. Lymph nodes (LNs) (18 patients) were the most frequent sites followed in order by lung (12) and liver (11). SBRT doses ranged from 45 to 60 Gy in three fractions (median 48 Gy). The cumulative gross tumor volume (GTV) ranged from 2 to 123 ml (median 13 ml). RESULTS: The median follow-up period from the SBRT date was 28 months (range, 6-65 months). The 3-year local control and overall survival rates were 64 and 60%, and the respective 5-year rates were 57 and 38%. Cumulative GTV and SBRT dose were statistically significant prognostic factors for local control. The grade 3 or 4 complications occurred in three patients (7%). CONCLUSIONS: High dose SBRT for colorectal oligometastases was found to produce results comparable with surgical series. To improve local control, dose higher than 48 Gy are recommend when possible, but further study will be required to define the optimal normal tissue constraints and acceptable toxicity.

Clinical outcomes of locking polymeric clip for laparoscopic appendectomy in patients with appendicitis: a retrospective comparison with loop ligature.

PURPOSE: This study aimed to compare the clinical outcomes of laparoscopic appendectomy (LA) according to the method of appendiceal stump closure. METHODS: Patients who underwent LA for appendicitis between 2010 and 2020 were retrospectively reviewed. Patients were classified into locking polymeric clip (LPC) and loop ligature (LL) groups. Clinical outcomes were compared between the groups. RESULTS: LPC and LL were used in 188 (56.6%) and 144 patients (43.4%), respectively for appendiceal stump closure. No significant differences were observed in sex, age, comorbidities, and the severity of appendicitis between the groups. The median operative time was shorter in the LPC group than in the LL group (64.5 minutes vs. 71.5 minutes, P=0.027). The median hospital stay was longer in the LL group than in the LPC group (4 days vs. 3 days, P=0.020). Postoperative incidences of intraabdominal abscess and ileus were higher in the LL group than in the LPC group (4.2% vs. 1.1%, P=0.082 and 2.8% vs. 0%, P=0.035; respectively). The readmission rate was higher in the LL group than that in the LPC group (6.3% vs. 1.1%, P=0.012). CONCLUSION: Using LPC for appendiceal stump closure during LA for appendicitis was associated with lower postoperative complication rate, shorter operative time, and shorter hospital stay compared to the use of LL. Operative time above 60 minutes and the use of LL were identified as independent risk factors for postoperative complications in LA. Therefore, LPC could be considered a more favorable closure method than LL during LA for appendicitis.

Mucinous rectal cancer: effectiveness of preoperative chemoradiotherapy and prognosis.

BACKGROUND: This study investigated the effects of preoperative chemoradiotherapy (PCRT) and the prognoses of patients with mucinous rectal cancer compared with those with nonmucinous cancer. METHODS: We retrospectively reviewed the medical records of 368 patients who underwent curative resection after PCRT, between 2000 and 2006, for midrectal to lower-rectal adenocarcinoma. Mucinous cancers were present in 23 patients (6.3%) and nonmucinous cancers in 345. In each patient, clinical stage before chemoradiotherapy was compared with pathologic stage to evaluate the extent of downstaging. Survival and multivariate analyses were performed using clinicopathologic variables. The median follow-up period was 42 months (range, 4-105 months). RESULTS: There was no difference in clinical stage between the groups. Although 58 patients (16.8%) in the nonmucinous group achieved pathologic complete responses (pCR), no mucinous group patient showed such a response. T-downstaging was more frequently observed in the nonmucinous than in the mucinous group (189 vs 7 [54.9% vs 30.4%], P = .03), but N-downstaging was similar in the 2 groups. The 5-year overall survival rate (OS) was significantly lower in the mucinous than in the nonmucinous group (64.8% vs 79.8%, P = .049). Multivariate analysis revealed that mucinous histotype was an independent (negative) prognostic factor for survival (hazard ratio, 2.36; 95% confidence interval, 1.05-5.3; P = .04). CONCLUSIONS: Patients with mucinous rectal cancer experienced a lower rate of T-downstaging after PCRT and had a poorer prognosis than did patients with nonmucinous cancer.

The Impact of Primary Tumor Resection on Survival in Asymptomatic Colorectal Cancer Patients With Unresectable Metastases.

PURPOSE: This study was conducted to evaluate the effectiveness of primary tumor resection (PTR) in asymptomatic colorectal cancer (CRC) patients with unresectable metastases using the inverse probability of treatment weighting (IPTW) method to minimize selection bias. METHODS: We selected 146 patients diagnosed with stage IV CRC with unresectable metastasis between 2001 and 2018 from our institutional database. In a multivariate logistic regression model using the patients' baseline covariates associated with PTR, we applied the IPTW method based on a propensity score and performed a weighted Cox proportional regression analysis to estimate survival according to PTR. RESULTS: Upfront PTR was performed in 98 patients, and no significant differences in baseline factors were detected. The upweighted median survival of the PTR group was 18 months and that of the non-PTR group was 15 months (P = 0.15). After applying the IPTW, the PTR was still insignificant in the univariate Cox regression (hazard ratio [HR], 0.26; 95% confidence interval [CI], 0.5-1.21). However, in the multivariate weighted Cox regression with adjustment for other covariates, the PTR showed a significantly decreased risk of cancer-related death (HR, 0.61; 95% CI, 0.40-0.94). CONCLUSION: In this study, we showed that asymptomatic CRC patients with unresectable metastases could gain a survival benefit from upfront PTR by analysis with the IPTW method. However, randomized controlled trials are mandatory.

Implication of FDG-PET/CT without synchronous colonic lesion in patients with stenotic left-sided colorectal cancer.

Although 18-fluoro-2-deoxy-glucose positron emission tomography/computed tomography (18F-FDG PET/CT) is useful for detecting synchronous colorectal cancer (CRC) in stenotic CRC, long-term outcomes of patients without synchronous FDG-avid lesions are not well reported. We investigated postoperative colonoscopy results in patients with left-sided stenosing CRC without synchronous FDG-avid lesions. In this retrospective review, 754 patients with left-sided CRC without synchronous FDG-avid lesions on preoperative 18F-FDG PET/CT were divided into two groups based on the completeness of preoperative colonoscopy. Propensity score matching was performed to balance baseline characteristics. Results of postoperative colonoscopy were compared in both the unmatched and matched cohorts. At 1 and 5 years after surgery, the cumulative risk of advanced adenoma (AA) or carcinoma (CA) in all patients, risk of CA, and additional surgical risk were 1.8% and 10.1%, 0.1% and 0.4%, and 0% and 0.5%, respectively. In both cohorts, the AA risk was significantly higher in the incomplete colonoscopy group. However, the risk of CA showed no between-group difference in the matched cohort. Additional surgical risk did not differ between the two groups. Thus, the finding of negative FDG-avid lesions in the proximal colon in addition to the target CRC ensures the absence of additional lesions warranting surgical plan changes.

Advanced Xenograft Model with Cotransplantation of Patient-Derived Organoids and Endothelial Colony-Forming Cells for Precision Medicine.

Preclinical evaluation models have been developed for precision medicine, with patient-derived xenograft models (PDXs) and patient-derived organoids (PDOs) attracting increasing attention. However, each of these models has application limitations. In this study, an advanced xenograft model was established and used for drug screening. PDO and endothelial colony-forming cells (ECFCs) were cotransplanted in NRGA mice (PDOXwE) to prepare the model, which could also be subcultured in Balb/c nude mice. Our DNA sequencing analysis and immunohistochemistry results indicated that PDOXwE maintained patient genetic information and tumor heterogeneity. Moreover, the model enhanced tumor growth more than the PDO-bearing xenograft model (PDOX). The PDO, PDOXwE, and clinical data were also compared in the liver metastasis of a colorectal cancer patient, demonstrating that the chemosensitivity of PDO and PDOXwE coincided with the clinical data. These results suggest that PDOXwE is an improvement of PDOX and is suitable as an evaluation model for precision medicine.

A Patient-Derived Organoid-Based Radiosensitivity Model for the Prediction of Radiation Responses in Patients with Rectal Cancer.

Patient-derived tumor organoids closely resemble original patient tumors. We conducted this co-clinical trial with treatment-naive rectal cancer patients and matched patient-derived tumor organoids to determine whether a correlation exists between experimental results obtained after irradiation in patients and organoids. Between November 2017 and March 2020, we prospectively enrolled 33 patients who were diagnosed with mid-to-lower rectal adenocarcinoma based on endoscopic biopsy findings. We constructed a prediction model through a machine learning algorithm using clinical and experimental radioresponse data. Our data confirmed that patient-derived tumor organoids closely recapitulated original tumors, both pathophysiologically and genetically. Radiation responses in patients were positively correlated with those in patient-derived tumor organoids. Our machine learning-based prediction model showed excellent performance. In the prediction model for good responders trained using the random forest algorithm, the area under the curve, accuracy, and kappa value were 0.918, 81.5%, and 0.51, respectively. In the prediction model for poor responders, the area under the curve, accuracy, and kappa value were 0.971, 92.1%, and 0.75, respectively. Our patient-derived tumor organoid-based radiosensitivity model could lead to more advanced precision medicine for treating patients with rectal cancer.

Delayed anastomotic leakage following sphincter-preserving surgery for rectal cancer.

PURPOSE: The aim of the present study was to investigate the characteristics of patients who developed delayed anastomotic leakage (DAL) following sphincter-preserving surgery for rectal cancer. We evaluated the following factors: (1) the incidence of DAL, (2) the clinical features of patients who developed DAL, (3) the risk factors for DAL, and (4) treatment outcomes. METHODS: We reviewed the case histories of 1,838 rectal cancer patients who had undergone curative resection with sphincter preservation and without protective stoma formation between January 2000 and December 2006. DAL was defined as the development of a pelvic abscess or fistula around the anastomosis more than 3 weeks post-surgery in patients without tumor recurrence who had resumed a normal diet and defecation. RESULTS: In 1.3% (24/1,838) of the patients, DAL developed on median postoperative day 99 (range 22-2,069). Pelvic abscess (50%) and anastomotic-vaginal fistula (41.7%) were the most common causes of DAL. Independent risk factors for the development of DAL were: (1) female gender (hazard ratio 3.03; 95% CI 1.06-8.8), (2) low-level anastomosis (< or = 4 cm from the anal verge) (hazard ratio 5.76; 95% CI 1.37-22.39), and (3) preoperative chemoradiation therapy (hazard ratio 4.56; 95% CI 1.4-14.92). Stoma formation was performed in all of the 24 patients. The 3-year stoma-retention rate in patients with DAL was significantly higher than in patients with early anastomotic leakage (72.2% vs 17.5%, P < 0.001). CONCLUSIONS: DAL following sphincter-preserving surgery for rectal cancer occurred relatively frequently in our sample and was associated with female gender, a low level of anastomosis, and preoperative radiotherapy. DAL patients required long-term or permanent stomas.

Clinicopathological characteristics of rectal carcinoids.

PURPOSES: Carcinoids are heterogeneous neuroendocrine tumors with malignant potential. The rectum is the third most common location for gastrointestinal carcinoids. We assessed the clinicopathological characteristics of rectal carcinoids. METHODS: A retrospective study of 203 patients treated for rectal carcinoids at the Asan Medical Center, Seoul, Republic of Korea from 1991 to 2007. RESULTS: The patients were on average 51 (18-83) years old. The male-to-female ratio was 1.48:1. Over half (62.1%) of the patients were asymptomatic. The most frequent symptoms in the symptomatic patients were abdominal pain (11.1%) and hematochezia (10.7%). Local excision was applied to 92.1%, low anterior resection to 4.9%, and biopsy only to 3.0% of total patients. Initially, 4.4% presented with distant metastasis. Distant metastasis rates for tumors < or =1 cm, >1 to < or =2 cm, and >2 cm were 1.7% (3/177), 15.0% (3/20), and 50.0% (3/6), respectively. In the follow-up period, three patients showed recurrences. The size, lymphovascular invasion, perineural invasion, and T and N stages were associated with distant metastasis. The overall 5-year survival rate was 94.0%. The TNM stage and presence of lymphovascular invasion were associated with lower survival. CONCLUSIONS: The chance that a rectal carcinoid will develop distant metastases increases as the tumor increases in size, lymphovascular invasion or perineural invasion is present, and T and N stages increase. The TNM stage and presence of lymphovascular invasion were associated with lower survival. Treatment plan should be chosen carefully considering above factors.

Butyrate enhances the efficacy of radiotherapy via FOXO3A in colorectal cancer patient­derived organoids.

Enhancing the radioresponsiveness of colorectal cancer (CRC) is essential for local control and prognosis. However, consequent damage to surrounding healthy cells can lead to treatment failure. We hypothesized that short­chain fatty acids (SCFAs) could act as radiosensitizers for cancer cells, allowing the administration of a lower and safer dose of radiation. To test this hypothesis, the responses of three­dimensional­cultured organoids, derived from CRC patients, to radiotherapy, as well as the effects of combined radiotherapy with the SCFAs butyrate, propionate and acetate as candidate radiosensitizers, were evaluated via reverse transcription­quantitative polymerase chain reaction, immunohistochemistry and organoid viability assay. Of the three SCFAs tested, only butyrate suppressed the proliferation of the organoids. Moreover, butyrate significantly enhanced radiation­induced cell death and enhanced treatment effects compared with administration of radiation alone. The radiation­butyrate combination reduced the proportion of Ki­67 (proliferation marker)­positive cells and decreased the number of S phase cells via FOXO3A. Meanwhile, 3/8 CRC organoids were found to be non­responsive to butyrate with lower expression levels of FOXO3A compared with the responsive cases. Notably, butyrate did not increase radiation­induced cell death and improved regeneration capacity after irradiation in normal organoids. These results suggest that butyrate could enhance the efficacy of radiotherapy while protecting the normal mucosa, thus highlighting a potential strategy for minimizing the associated toxicity of radiotherapy.