Purpose: Since the introduction of robotic surgery, robots for colorectal cancer have replaced laparoscopic surgery, and a single-port robot (SPR) platform has been launched and is being used to treat patients. We analyzed the learning curve and initial complications of using an SPR platform in colorectal cancer surgery. Methods: We reviewed 39 patients who underwent SPR colectomy from April to October 2019. All surgeries were performed by the same surgeon using an SPR device. A learning curve was generated using the cumulative sum methodology to assess changes in total operation time, docking time, and surgeon console time. We grouped the patients into 3 groups according to the time period: the first 11 were phase 1, the next 11 were phase 2, and the last 17 were phase 3. Results: The mean age of the patients was 61.28±13.03 years, and they had a mean body mass index of 23.79±2.86 kg/m2. Among the patients, 23 (59.0%) were male, and 16 (41.0%) were female. The average operation time was 186.59±51.30 minutes, the average surgeon console time was 95.49±35.33 minutes, and the average docking time (time from skin incision to robot docking) was 14.87±10.38 minutes. The surgeon console time differed significantly among the different phases (P<0.001). Complications occurred in 8 patients: 2 ileus, 2 postoperation hemoglobin changes, 3 urinary retentions, and 1 complicated fluid collection. Conclusion In our experience, the learning curve for SPR colectomy was achieved after the 18th case.

Purpose: For the treatment of locally advanced rectal cancer (LARC), research on primary lesions with mesorectal fascia (MRF) involvement is lacking. This study analyzed the clinical outcomes and efficacy of dose-escalated neoadjuvant concurrent chemoradiotherapy (NCRT) to patients with LARC involving MRF. Materials and Methods: We retrospectively reviewed 301 patients who were diagnosed with LARC involving MRF and underwent NCRT followed by total mesorectal excision (TME). Patients who received radiotherapy (RT) doses of ≤50.4 Gy were defined as the non-boost group, while ≥54.0 Gy as the boost group. Pathological tumor response and survival outcomes, including intrapelvic recurrence-free survival (IPRFS), distant metastases-free survival (DMFS) and overall survival (OS), were analyzed. Results: A total of 269 patients (89.4%) achieved a negative pathological circumferential resection margin and 104 (34.6%) had good pathological tumor regression grades. With a median follow-up of 32.4 months, IPRFS, DMFS, and OS rates at 5-years were 88.6%, 78.0%, and 91.2%, respectively. In the subgroup analysis by RT dose, the boost group included more advanced clinical stages of patients. For the non-boost group and boost group, 5-year IPRFS rates were 90.3% and 87.0% (p = 0.242), 5-year DMFS rates were 82.0% and 71.3% (p = 0.105), and 5-year OS rates were 93.0% and 80.6% (p = 0.439), respectively. Treatment related toxicity was comparable between the two groups (p = 0.211). Conclusion Although this retrospective study failed to confirm the efficacy of dose-escalated NCRT, favorable IPRFS and pathological complete response was achieved with NCRT followed by TME. Further studies combining patient customized RT dose with systemic therapies are needed.

Purpose: Identification of type I protein arginine methyltransferase (PRMT) substrates and their functional significance during tumorigenesis is becoming more important. The present study aimed to identify target substrates for type I PRMT using 2-dimensional (2D) gel electrophoresis (GE) and 2D Western blotting (WB). Methods: Using immunoblot analysis, we compared the expression of type I PRMTs and endogenous levels of arginine methylation between the primary colorectal cancer (CRC) and adjacent noncancerous tissues paired from the same patient. To identify arginine-methylated proteins in HCT116 cells, we carried out 2D-GE and 2D-WB with a type I PRMT product-specific antibody (anti-dimethyl-arginine antibody, asymmetric [ASYM24]). Arginine-methylated protein spots were identified by mass spectrometry, and messenger RNA (mRNA) levels corresponding to the identified proteins were analyzed using National Center for Biotechnology Information (NCBI) microarray datasets between the primary CRC and noncancerous tissues. Results: Type I PRMTs and methylarginine-containing proteins were highly maintained in CRC tissues compared to noncancerous tissues. We matched 142 spots using spot analysis software between a Coomassie blue (CBB)-stained 2D gel and 2D-WB, and we successfully identified 7 proteins that reacted with the ASYM24 antibody: CACYBP, GLOD4, MAPRE1, CCT7, TKT, CK8, and HSPA8. Among these proteins, the levels of 4 mRNAs including MAPRE1, CCT7, TKT, and HSPA8 in CRC tissues showed a statistically significant increase compared to noncancerous tissues from patients using the NCBI microarray datasets. Conclusion Our results indicate that the method shown here is useful in identifying arginine-methylated proteins, and significance of arginine modification in the proteins identified here should be further identified during CRC development.

Recently, abdominoperineal resection (APR) using a robot has been demonstrated in other studies. However, there has been no report on APR for rectal cancer using the single-port robot (SPR) platform. In response to this research gap, we described the clinical experience of APR using a SPR. From April 2019 to March 2020, APR using a SPR platform was performed in a total of 4 patients. Three patients had a transumbilical approach, and 1 patient had a transstoma site approach. The average operation time was 307 minutes, and the patient docking time to the SPR platform was 133.5 minutes. There were no complications during the operation, and no laparoscopy or open conversion. No reoperation occurred within 30 days. Mild postoperative complications occurred in 2 patients. We found that APR has safety and feasibility in surgery using an SPR platform. There was no intraoperative event and severe postoperative complications.

Purpose: We analyzed the learning curve of single-port robotic (SPR)-assisted rectal cancer surgery. Methods: Fifty-seven consecutive SPR-assisted rectal cancer surgery cases performed by the same surgeon were considered in surgical interventions for rectal cancer. Total operation time (OT), docking time (DT), and surgeon console time (SCT) measured during surgery were used to parametrize the learning curve. The parameters representing the learning curve were evaluated using the cumulative sum (CUSUM). Results: The mean value of total OT was 241.8 ± 91.7 minutes, the mean value of DT was 20.6 ± 19.1 minutes, and the mean value of SCT was 135.9 ± 66.7 minutes. The learning curve was divided into phase 1 (initial 16 cases), phase 2 (second 16 cases), and phase 3 (subsequent 25 cases). The peak on the CUSUM graph occurred in the 21st case. The longest OT among phases was in phase 2. Complications were most frequent in phase 2. However, complications of Clavien-Dindo (CD) grade IIIb were most frequent in phase 3 with 2 patients. The most common complications were fluid collection and urinary retention (7 patients each). Complications of CD grade IIIb required one stomal revision due to stoma obstruction and one irrigation and loop ileostomy due to anastomosis leakage. Conclusion Improvement in surgical performance of SPR assisted rectal cancer operation was achieved after 21 cases.The three phases identified in the cumulative sum analysis showed a significant decrease in operative time after the middle stage of the learning curve without an increase in the complication rate.

Purpose: The prognostic impact of anastomotic leakage (AL) in rectal cancer remains uncertain. We investigated the prognostic significance of AL in rectal cancer patients who underwent curative surgery, especially in terms of chemoradiotherapy. Methods: A total of 1,818 rectal cancer patients who underwent radical surgery from 2011 to 2015 were retrospectively evaluated. We categorized patients according to AL and compared survival outcomes between the groups before and after matching. In locally advanced rectal cancer patients, we classified patients according to neoadjuvant chemoradiotherapy (nCRT) or adjuvant chemotherapy (aCTx) and analyzed survival outcomes according to AL in each group. Results: Before matching, overall survival (OS) was significantly worse in the AL (+) group compared to the AL (–) group (P = 0.004). In matched patients, there were no differences in disease-free survival (DFS) and OS between groups (P = 0.423 and P = 0.083, respectively). In subgroup analysis for locally advanced rectal cancer, patients were classified as follows: nCRT (+) and aCTx (+) group; nCRT (+) and aCTx (–) group; nCRT (–) and aCTx (+) group; and nCRT (–) and aCTx (–) group. In the nCRT (–) and aCTx (+) group, patients with AL exhibited significantly worse DFS than patients without AL (P = 0.040). In the other 3 groups, there were no differences in DFS according to AL. Conclusion In locally advanced rectal cancer, AL had an adverse effect on oncologic outcome in patients receiving aCTx without nCRT but not in patients receiving nCRT.

Purpose: Various clinical practice guidelines recommend at least 12 regional lymph nodes should be removed for resected colon cancer. According to a recent study, the lymph node yield (LNY) in colon cancer surgery in the last 20 years has tended to increase from 14.91 to 21.30. However, it is unclear whether these guidelines adequately reflect recent findings on the number of harvested lymph nodes in colon cancer surgery. The aim of this study is to assess the impact of an LNY of more than 25 on survival in right-sided colon cancer. Methods: We included 285 patients who underwent a right hemicolectomy during the period from January 2010 through December 2015. Patients were divided into two groups (<25 nodes and ≥25 nodes). Primary endpoints included 5-year and 10-year survival including disease-free and overall. Results: We found that survival outcomes of patients with a harvest of ≥25 nodes were not significantly different compared with a <25 group. Large tumor size (5 cm) is significantly associated with poor 5-year and 10-year overall survival. Conclusion Survival outcomes of patients with a harvest of ≥25 nodes were not significantly different compared with the <25 group in stage II colon cancer with no risk.

Purpose: Indications for local excision in patients with rectal cancer remain controversial. We reviewed factors affecting survival rate and treatment effectiveness in cancer recurrence after local excision among patients with rectal cancer. Materials and Methods: A total of 831 patients was enrolled. Of these, 391 patients were diagnosed with primary rectal cancer and underwent local excision. A retrospective observational study was performed on patients who underwent full-thickness local excision for rectal cancer. Results: The median duration of follow-up was 61 months. The overall recurrence rate was 11.5%. The rate of local recurrence was 5.1%. Five-year overall survival rate among recurrent patients was 66.8%; the rate among patients who underwent salvage operation due to recurrence was 84.7%, compared with 44.2% among patients treated with non-operative management (p<0.001).Multivariate analysis of disease-free survival identified distance from the anal verge (p=0.038) and histologic grade (p=0.047) as factors predicting poor prognosis. Multivariate analysis of overall survival showed that age (p<0.001), serum carcinoembryonic antigen (CEA) levels (p=0.001), and histologic grade (p=0.013) also affected poor prognosis. In subgroup analysis of patients with recurrence, 25 patients underwent reoperation, while 20 patients did not. For 5-year overall survival rate, there was a significant difference between 84.7% of the reoperation group and 44.2% of the non-operation group (p<0.001). Conclusion The risk factors affecting overall survival rate after local excision were age 65 years or older, preoperative CEA level 5 or higher, and high histologic grade. In cases of recurrence after local excision of rectal cancer, salvage operation might improve overall survival.

Purpose: Coronavirus disease 2019 (COVID-19) has affected many parts of daily life and healthcare, including cancer screening and diagnosis. The purpose of this study was to determine whether there was an upshift in the colorectal cancer stage at diagnosis due to delays related to the COVID-19 outbreak. Methods: From January to June of each year from 2017 to 2020, a total of 3,229 patients who were first diagnosed with colorectal cancer were retrospectively reviewed. Those enrolled from 2017 to 2019 were classified as the ‘pre-COVID’ group, and those enrolled in 2020 were classified as the ‘COVID’ group. The primary outcome was the rate of stage IV disease at the time of diagnosis. Results: There was no statistically significant difference in the proportion of stage IV patients between the pre-COVID and COVID groups (P=0.19). The median preoperative carcinoembryonic antigen level in the COVID group was higher than in the pre-COVID group in all stages (all P<0.05). In stage I, II patients who underwent radical surgery, the lymphatic invasion was more presented in COVID patients (P=0.009). Conclusion We did not find significant stage upshifting in colorectal cancer during the COVID-19 outbreak. However, there were more initially unresectable stage IV colorectal cancer patients with a low conversion rate to resectable status, and more patients had factors related to poor prognosis. These results may become more apparent over time, so it is vital not to neglect cancer screening to not delay the diagnosis during the COVID-19 epidemic.

Purpose: The survival benefit of neoadjuvant chemotherapy (NAC) prior to surgical resection in colorectal cancer with liver metastases (CRCLM) patients remains controversial. The aim of this study was to compare overall outcome of CRCLM patients who underwent NAC followed by surgical resection versus surgical treatment first. Methods: We retrospectively analyzed 429 patients with stage IV colorectal cancer with synchronous liver metastases who underwent simultaneous liver resection between January 2008 and December 2016. Using propensity score matching, overall outcome between 60 patients who underwent NAC before surgical treatment and 60 patients who underwent surgical treatment first was compared. Results: Before propensity score matching, metastatic cancer tended to involve a larger number of liver segments and the primary tumor size was bigger in the NAC group than in the primary resection group, so that a larger percentage of patients in the NAC group underwent major hepatectomy (P<0.001). After propensity score matching, demographic features and pathologic outcomes showed no significant differences between the 2 groups. In addition, there was no significant difference in short-term recovery outcomes such as postoperative morbidity (P=0.603) and oncologic outcome, including 3-year overall survival rate (P=0.285) and disease-free survival rate (P=0.730), between the 2 groups. Conclusion NAC prior to surgical treatment in CRCLM is considered a safe treatment that does not increase postoperative morbidity, and its impact on oncologic outcome was not inferior.