Impact of surgical proximal and distal margins on the recurrence of resectable colon cancer: a single-center observational cohort study.

PURPOSE: Few studies have investigated the impact of the surgical proximal and distal margins on colon cancer recurrence. We conducted this study to investigate the effect of resection margins on the prognosis of resectable colon cancer. METHODS: We analyzed data on 1458 patients who underwent colorectal resection in our institute between January, 2004 and March, 2020, including 579 patients with resectable colon cancer. The association between the resection margin and recurrence for each oncological status was assessed and the value of the resection length that influenced recurrence was analyzed. RESULTS: Patients who had pT4 colon cancer with margins of more than 7 cm had a trend of fewer recurrences and longer relapse-free survival (RFS) than those with colon cancer of other stages (P = 0.033; hazard ratio [HR], 0.42; 95% confidence interval [CI], 0.20-0.89). Multivariate analysis identified a margin of < 7 cm as an independent risk factor for RFS in patients with pT4 colon cancer (P = 0.023; HR, 2.65; 95% CI 1.013-6.17). No correlation was found between resection margins and recurrence, depending on the extent of lymph node metastasis and tumor location. CONCLUSION: A resection margin of at least 7 cm should be maintained for patients with pT4 colon cancer.

Close distal margin is associated with locoregional rectal cancer recurrence: A multicenter study.

BACKGROUND AND OBJECTIVES: The importance of the radial margin for rectal cancer resection is well understood. However, surgeons have deemphasized the distal margin, accepting very close distal margins to perform sphincter-preserving surgery. We hypothesized that distal margins < 1 cm would be an independent risk factor for locoregional recurrence. The objective was to determine whether close distal margins are associated with increased locoregional recurrence risk. METHODS: This was a multi-institutional retrospective cohort study conducted at six academic medical centers including patients who received low anterior resection surgery for primary rectal cancer between 2007 and 2018. RESULTS: Of 556 low anterior resection patients, the rate of close distal margin was 12.8% (n = 71), and the locoregional recurrence rate was 5.0% (n = 28). The locoregional recurrence rate for close distal margin cases was 9.9% (n = 7) compared to 4.3% (n = 21) for distal margins ≥1.0 cm. In multivariable analysis, the only factor significantly associated with locoregional recurrence was close distal margin (adjusted odds ratio: 2.80, confidence interval: 1.08-7.25, p = 0.035). CONCLUSIONS: Rectal cancer patients with close distal margins (<1 cm) following low anterior resection had a significantly higher risk for locoregional recurrence. Therefore, the decision to perform low anterior resection with margins < 1 cm should be taken with caution.

Minimum resection length to ensure a pathologically negative distal margin and the preservation of a larger remnant stomach in proximal gastrectomy for early upper gastric cancer.

BACKGROUND: In proximal gastrectomy (PG), a longer distal margin (DM) length should be maintained to obtain a pathologically negative DM. However, a shorter DM length is preferred to preserve a large remnant stomach for favorable postoperative outcomes. Evidence regarding the minimum DM length to ensure a pathologically negative DM is useful. METHODS: Patients who underwent PG or total gastrectomy for cT1N0M0 gastric cancer limited to the upper third were enrolled. A new parameter, ΔDM, which corresponded to the pathological extension distal to the gross tumor boundary towards the resection stump, was evaluated. The maximum ΔDM, which is the length ensuring a pathologically negative DM, was first determined. Furthermore, the possible incidences of pathologically positive DM were calculated for each pathological type and clinical tumor (cTumor) size. RESULTS: Of 361 patients eligible for this study, 190 and 171 were assigned to differentiated (Dif) and undifferentiated types (Und), respectively. The maximum ΔDM was 30 and 40 mm in Dif and Und, respectively. Considering a correlation between cTumor size and ΔDM, and possible incidences of pathologically positive DM, 10, 20, and 30 mm were the minimal gross DM lengths in Dif when cTumor size was ≤ 15 mm, > 15 and ≤ 50 mm, and > 50 mm, respectively. In Und, the incidences of pathologically positive DM were 0.59% and 2.3% for gross DM lengths of 30 and 20 mm, respectively. CONCLUSION: The minimum DM lengths to ensure a pathologically negative DM in PG are proposed according to the pathological type of early upper gastric cancer.

Oncological outcome of wide anatomic resection with partial mesorectal excision in patients with upper and middle rectal cancer.

AIM: The aim was to investigate the influence of distal resection margin and extent of mesorectal excision on long-term oncological outcomes. METHOD: Consecutive patients with upper and middle third rectal cancer from June 2006 to February 2016 were reviewed. Patients were divided into four groups depending on the distal margin considered as a surrogate marker of the extension of mesorectal excision (Q1 ≤10 mm, Q2 11-20 mm, Q3 21-30 mm, Q4 ≥31 mm). Local-recurrence-free survival (LRFS), disease-free survival (DFS) and overall survival (OS) were estimated. Cox regression models were used to investigate the influence of surgical and clinicopathological variables on prognosis by adjusting for confounding factors. RESULTS: Two hundred and eleven patients with mid (125) and upper (86) rectal cancer underwent wide mesorectal excision. The median follow-up was 48.64 months (interquartile range 28-63). 17.5% patients developed recurrence. The 5-year LRFS, DFS and OS for all patients were 93.20%, 83.89% and 80.1%, respectively, with no statistically significant differences between groups (LRFS, P = 0.601; DFS, P = 0.487; OS, P = 0.468). In the multivariable analysis the recurrences and survival were associated with the quality of the mesorectum (LRFS, hazard ratio 10.629, 95% CI 2.324-48.610, P = 0.002; DFS, hazard ratio 2.789, 95% CI 1.314-5.922, P = 0.008). CONCLUSION: A wide anatomical resection with partial mesorectal excision and shorter distal resection margin does not jeopardize the oncological outcomes.

Clinical factors affecting the distal margin in rectal cancer surgery.

PURPOSE: In rectal cancer surgery, an insufficient distal margin (DM) is associated with a high risk of local recurrence, whereas an excessive DM will cause low anterior resection syndrome, impairing quality of life. This study aimed to identify the factors that affect the distance between the colorectal resection site and the tumor to optimize achieving the correct DM. METHODS: The subjects of this study were 219 patients who underwent resection for primary rectal cancer in our department between January 2006 and July 2014. According to Japanese guidelines, DM (rDM) was based on the tumor location, but the pathological DM (pDM) was measured from surgical specimens. The patients were divided into two groups: the pDM-less-than-rDM group (pDM < rDM) and the pDM-greater-or-equal-to-rDM group (pDM ≥ DM). The factors associated with the DM in the two groups were compared. RESULTS: In the pDM < rDM group, the tumor distance from the anal verge was shorter (p = 0.001) and significantly more patients underwent laparotomy (p = 0.047). CONCLUSION: The DM tended to be shorter than that planned by the surgeon in patients with lower rectal cancers and those treated by laparotomy,; therefore, when performing rectal resection, care must be taken to ensure that the pDM is not shorter than the rDM.

Augmented CD133 expression in distal margin correlates with poor prognosis in colorectal cancer.

Pathological assessment of excised tumour and surgical margins in colorectal cancer (CRC) play crucial role in prognosis after surgery. Molecular assessment of margins could be more sensitive and informative than conventional histopathological analysis. Considering this view, we evaluated the distal surgical margins for expression of cancer stem cell (CSC) markers. Cellular and molecular assessment of normal, tumour and distal margin tissues were performed by flow cytometry, real-time q-PCR and immuno-histochemical analysis for CRC patients after tumour excision. CRC patients were evaluated for expression of CSC markers in their normal, tumour and distal tissues. Flow cytometry assay revealed CD133 and CD44 enriched cells in distal margin and tumour compared to normal colorectal tissues, which was further confirmed by immunohistochemistry. Most importantly, immunohistochemistry also revealed the enrichment of CSC markers expression in pathologically negative distal margins. Patients with distal margin enriched for CD133 expression showed an increased recurrence rate and decreased disease-free survival. This study proposes that although distal margin seems to be tumour free in conventional histopathological analysis, it could harbour cells enriched for CSC markers. Further CD133 could be a promising molecule to be used in molecular pathology for disease prognosis after surgery in CRC patients.

Real-time in vivo optical biopsy using confocal laser endomicroscopy to evaluate distal margin in situ and determine surgical procedure in low rectal cancer.

BACKGROUND: In low rectal cancer, a negative distal margin (DM) is necessary for R0 radical resection, and therefore, the choice of surgical procedure is dependent on whether the planned transection rectum has residual cancer or not. Currently, surgeons choose surgical procedures according to intraoperative in vitro DM frozen sections. This study aimed to investigate the feasibility of real-time in vivo optical biopsy using confocal laser endomicroscopy (CLE) to evaluate DM in situ and determine the surgical procedure in low rectal cancer. METHODS: Optical biopsy using CLE was performed when the rectum was dissected at the levator ani plane and rectum transection was ready. For negative DM, the surgical procedure of low anterior resection (LAR) was chosen. For positive DM, the surgical procedure of abdominoperineal resection (APR) was chosen. The specimen at the site of the planned transection rectum underwent intraoperative frozen section and routine pathological procedures. RESULTS: Eighteen patients underwent real-time in vivo optical biopsy using CLE in surgery. Eleven patients' CLE images of DM showed a regular, round crypt, and round luminal opening covered by a simple layer of columnar epithelial cells and goblet cells. LAR was then performed. Pathology revealed that the 11 DMs were negative, and the median length of the DMs was 2.0 cm. The remaining seven patients' CLE images of the planned transection rectum showed the loss of crypt architecture and irregular epithelial layer with loss of goblet cells. APR was then performed. Pathology confirmed cancer invasion, and the median distance from tumor to dentate line was 1.0 cm. The sensitivity, specificity, and accuracy of CLE optical biopsy of DM were 85.71%, 100%, and 94.44%, respectively. CONCLUSIONS: It is feasible to perform real-time in vivo optical biopsy using CLE to evaluate DM in situ and determine the surgical procedure in low rectal cancer.

Effect of preoperative chemotherapy on distal spread of low rectal cancer located close to the anus.

PURPOSE: This study aimed to clarify the frequency of distal spread and the optimal distal margin after preoperative chemotherapy for advanced low rectal cancer. METHODS: The study included patients with advanced lower rectal cancer who received preoperative chemotherapy and underwent surgery during 2012-2015. We investigated the distal spread of tumor cells, defined as the distal distance from the intramucosal distal tumor edge to the farthest tumor cells located under the submucosal layer. Clinical characteristics were compared for distal spreads ≥ 10 and < 10 mm, and risk factors for distal spread ≥ 10 mm were investigated. RESULTS: Of the 71 patients, 42 (59%) showed distal spread. Distal spreads of 1-9, 10-19, and ≥ 20 mm were observed in 27 (38%), 11 (15%), and 4 (6%) patients, respectively. Multivariate analysis revealed two independent risk factors for distal spread ≥ 10 mm after preoperative chemotherapy. The first risk factor is the presence of different therapeutic effects between the mucosal and deeper layers (meaning that superficial tumor shrinkage was evident on colonoscopy, but little tumor shrinkage was evident on magnetic resonance imaging) (odds ratio, 11.6; 95% CI, 2.22-61.3). The second risk factor is poorly differentiated or mucinous adenocarcinoma (odds ratio, 8.86; 95% CI, 1.58-49.9). CONCLUSION: A distal margin of 20 mm is required (10 mm is insufficient) for advanced lower rectal cancer patients who receive preoperative chemotherapy followed by surgery. Independent risk factors for distal spread ≥ 10 mm include (1) the presence of different therapeutic effects between mucosal and deeper layers and (2) poorly differentiated or mucinous adenocarcinomas.

Necessary circumferential resection margins to prevent rectal cancer relapse after abdomino-peranal (intersphincteric) resection.

PURPOSE: The purpose of this study was to determine the adequate circumferential resection margin (CRM) for abdomino-peranal (intersphincteric) resection (ISR) that would prevent the relapse of rectal cancers. METHODS: The records of 41 cases that underwent curative ISR for rectal cancer were retrospectively reviewed. The relapse-free survival rates and overall survival rates were evaluated and correlated with the maximum depth of the inner muscularis layer reached during ISR (i.e., the radial margin [RM] and distal margin [DM]). Cases were divided into three groups based on the sizes of the RM and DM: (1) group A (RM >2 mm and DM >1.5 cm), (2) group B (RM >2 mm or DM >1.5 cm but not both), and (3) group C (RM <2 mm and DM <1.5 cm). RESULTS: The relapse-free survival rates of the cases in group C were lower than those in the cases of group A or group B (p = 0.002 and 0.037, respectively). The resection margins required to prevent rectal cancer relapse were >2 mm for the RM and >1.5 cm for the DM. For these margins, the intersphincteric space had to be entered (i.e., between the internal and external anal sphincters). CONCLUSION: It is critical to enter the intersphincteric space to ensure an adequate CRM (RM >2 mm and DM >1.5 cm) for preventing rectal cancer recurrence after ISR.

Frozen section examination may facilitate reconstructive surgery for mid and low rectal cancer.

BACKGROUND: Distal margin >1 cm provides an oncologic safety in low-lying rectal cancers. We evaluated the accuracy of frozen section (FS) examination in estimating distal margins, and its impact on intraoperative decision making regarding restorative proctectomy. METHODS: Retrospective study of patients who underwent surgery for adenocarcinoma of the mid or lower rectum during 2001-2010 and for whom a distal margin specimen was examined intraoperatively by FS, to confirm microscopically free margins. Intraoperative findings, and frozen and final paraffin section findings were retrieved from patient charts. A distal margin of ≤1 cm was compared with >1 cm, for free margins at final pathology and local recurrence (LR). The impact of a distal margin ≤5 mm was also assessed. The impact of FS on intraoperative decision making, in patients who did and did not receive preoperative chemoradiotherapy, was assessed. RESULTS: The mean age of the 63 patients studied was 66.4 ± 11.8 years, and median tumor distance from the anal verge 6 cm (range 1-10 cm). Seven patients underwent abdominoperineal resection, 54 anterior resection, and two Hartman procedures. FS sensitivity and specificity were 83% and 98%, respectively. Accuracy of FS was high for the 41 patients treated with preoperative chemoradiotherapy, and the 22 who were not. Distal margin >5 mm at FS examination ensured a free margin at final pathology. LR rate was comparable between patients with distal margin >10 mm and ≤10 mm, 8% vs 11%, P = 0.65. CONCLUSIONS: FS examination may help determine free distal margin and consequently, in selected cases, may facilitate a restorative procedure in patients with low rectal cancer.

Endoscopic tattooing to mark distal margin for low anterior rectal and select sigmoid resections.

Obtaining a reliable distal margin during anterior colorectal resection can be difficult. In this study, endoscopic transmural tattoos were placed to mark the distal transection point in patients with distal colorectal neoplasms who undergo bowel resection. In the operating room, before surgery, sigmoidoscopy is performed with a 2-channel scope using CO2 insufflation. Through channel 1, a biopsy forceps, marked 5 cm from its end, is inserted to the tumor's distal edge; in channel 2, a sclerotherapy catheter is placed. The scope is then withdrawn and forceps inserted at the same rate until the mark is seen, next, via the needle catheter, 4 tattoos are placed at that level circumferentially. After rectal mobilization, visible external tattoos guide stapler placement. If no tattoo is seen, sigmoidoscopy is done and the tattoos used to guide stapler placement. In all 27 patients, the tattoos guided stapler placement; tattoos were seen via the abdomen in 26 and the stapler placed as per tattoos in 25. In 2 patients, repeat endoscopy was done and tattoos used to guide or confirm stapler placement. The margin was ≤1 cm from target in 74% while in 22% the margin was 2 to 3.5 cm off target (mean deviation from target margin = 0.33 cm). In conclusion, this method facilitates stapler placement and provides more reliable margins.

Impact of Microscopically Positive (≤1 mm) Distal Margins on Disease Recurrence in Rectal Cancer Treated by Neoadjuvant Chemoradiotherapy.

BACKGROUND: The adequate distal resection margin is still controversial in rectal cancer treated by neoadjuvant chemoradiotherapy (nCRT). The aim of this study was to assess the impact of a distal margin of ≤1 mm on locoregional recurrence-free survival (LRRFS). METHODS: Among 255 patients treated with nCRT and surgery at the National Cancer Institute of Milan, 83 (32.5%) had a distal margin of ≤1 mm and 172 (67.5%) had a distal margin of >1 mm. Survival analyses were performed to assess the impact of distal margin on 5-year LRRFS, as well as Cox survival analysis. The role of distal margin on survival was analyzed according to different tumor regression grades (TRGs). RESULTS: The overall 5-year LRRFS rate was 77.6% with a distal margin of ≤1 mm vs. 88.3% with a distal margin of >1 mm (Log-rank p = 0.09). Only stage ypT4 was an independent predictor of worse LRRFS (HR 15.14, p = 0.026). The 5-year LRRFS was significantly lower in TRG3-5 patients with a distal margin of ≤1 mm compared to those with a distal margin of >1 mm (68.5% vs. 84.2%, p = 0.027), while no difference was observed in case of TRG1-2 (p = 0.77). CONCLUSIONS: Low-responder rectal cancers after nCRT still require a distal margin of >1 mm to reduce the high likelihood of local relapse.

Transanal Total Mesorectal Excision for Rectal Cancer: Toward Standardization of the Surgical Technique.

Laparoscopic surgery is widely used for rectal cancer; however, this technique is challenging due to tapering of the mesorectum in the pelvis, and the forward angle of the distal rectum, which renders this part of the rectum less accessible from the abdominal cavity. Hence, concerns regarding its safety and curability have been raised, particularly for inadequate distal and circumferential resection margins. Recently, transanal total mesorectal excision (TaTME), which involves endoscopic total mesorectal excision (TME) retrogradely from the anal side, has attracted attention worldwide as a solution to these problems. TaTME is superior to the conventional laparoscopic approach for rectal cancer in terms of both oncological and functional preservations. However, a shallow learning curve caused by the unfamiliar anatomical view from the anal side can pose challenges. Therefore, an efficient educational system needs to be established. Randomized controlled trials comparing conventional laparoscopic TME with TaTME are ongoing to demonstrate the usefulness of TaTME. This article reviews changes in the surgical treatment of rectal cancer, with a focus on TaTME, and describes the indications, surgical techniques, and training curricula for TaTME.

The Impact of Narrow and Infiltrated Distal Margin After Proctectomy for Rectal Cancer on Patients' Outcomes: a Systematic Review and Meta-analysis.

Rectal cancer is a common tumor within a difficult anatomic constraint. Total mesorectal excision with longitudinal and circumferential free margins is considered imperative for good prognosis. In this article, the authors systematically reviewed all published literature with specific Mesh terms until the end of year 2019. Thereafter, retrieved articles were assessed using the Newcastle-Ottawa Scale and meta-analysis was conducted comparing local recurrence among 1-cm, 5-mm, and narrow (< 1-mm)/infiltrated margins. Thirty-nine articles were included in the study. Macroscopic distal margin < 1 cm carried a higher incidence of recurrence for those who did not receive neoadjuvant radiation, without affecting neither estimated overall nor disease-free survival. Less than 5-mm margin after radiation therapy is accepted oncologically. Infiltrated margins and narrow margins (< 1 mm) microscopically are associated with higher incidence of local recurrence and shorter overall and disease-free survival. Surgeons should aim at 1-cm safety margin in radiotherapy-naïve patients and microscopic free margin > 1 mm for those who received neoadjuvant therapy. The cost/benefit of reoperation for patients with infiltrated margins is still inadequately studied.

Distal resection margins in rectal cancer specimens: differences in assessment between surgeons and pathologists and the influence of neoadjuvant chemoradiation.

To investigate the discrepancy between the distal resection margin (DRM) assessed by surgeons and pathologists, and the impact of neoadjuvant chemoradiotherapy (nCRT) on DRM. This study included 67 rectal cancer patients undergoing elective surgery. DRMs were assessed through four different techniques: in vivo subjective estimative, made by the surgeon before the rectal resection (by palpation and visual estimative); in vivo objective, measured with a ruler before the rectal transection; ex vivo objective, measured right after resection of the specimen; post-fixation objective measurement, conducted by the pathologist. The DRMs subjectively and objectively assessed by the surgeons were not significantly different (3.40 cm vs. 3.45 cm). There was a mean reduction in the length of DRMs of 35.6%, from 3.45 cm objectively measured by the surgeon to 2.20 cm measured by the pathologist. This difference was significant among patients that did not receive nCRT (3.90 cm vs. 2.30 cm, P < 0.001), but not among those who received nCRT (2.30 vs. 2.05 cm). Surgeons are accurate in assessing rectal cancer DRMs. There are significant differences between intraoperative measurements of DRMs and the final pathologic results. However, these differences are not seen when nCRT is used, a finding that may be useful when sphincter preservation is being considered.

Is proximal gastrectomy indicated for locally advanced cancer in the upper third of the stomach?

AIM: To treat upper third gastric cancer, proximal gastrectomy (PG), a function-preserving procedure, is recommended for early lesions when at least half the distal stomach can be preserved, while total gastrectomy (TG) is standard for locally advanced lesions. Oncological feasibility, when applying PG for such lesions, remains unknown. METHODS: We reviewed patients undergoing TG for clinical (c) T2-T4 upper third gastric cancer between 2006 and 2015. Preoperative tumor locations were further classified into the cardia, fornix, and gastric body based on endoscopic findings. The metastatic rate and therapeutic value index for lymph node (LN) dissection were determined, and characteristics of patients with distal LN (No. 4d, 5, and 6) metastasis (DLNM) were reviewed. In addition, patients with pathological tumor invasion to the middle third (M) region were investigated. RESULTS: We studied 167 patients. There were 8 (4.8%) with DLNM and 41 (24.6%) with pathological tumor invasion to the M region. As to regional stations, therapeutic indices for LN dissection at stations No. 4d, 5, 6, and 12a were zero or extremely low. No DLNM was detected in cT2 lesions or cT3/T4 lesions located within the cardia and/or the fornix. In addition, none of the lesions located within the cardia and/or the fornix by preoperative endoscopy extended to the M region in the pathological specimen. CONCLUSIONS: For upper third gastric cancer, PG without No. 12a dissection might be acceptable for cT2-T4 lesions located within the cardia and/or the fornix when considering the risk of DLNM and cancer-positivity in the distal stump.

Is Intraluminal Washout Necessary for Patients with Sigmoid Colon Cancer to Eliminate Exfoliated Cancer Cells as in Patients with Rectal Cancer? A Pilot Study at a Single Institute.

OBJECTIVES: Rectal stump washout has been widely performed to prevent the implantation of exfoliated cancer cells (ECCs) in patients with rectal cancer. However, it remains unclear whether intraluminal washout before transection is required in patients with sigmoid colon cancer. Therefore, this pilot study was conducted to elucidate the necessity of intraluminal washout for sigmoid colon cancer patients in comparison with rectal cancer patients by cytological assessments. METHODS: A total of 16 patients with sigmoid colon cancer and 24 patients with rectal cancer who underwent sigmoidectomy or anterior resection with anastomosis using double-stapling technique were enrolled. A transanal washout sample was collected before washout and after irrigation with 500 and 1,000 mL of saline. Cytological assessments were conducted according to the Papanicolaou classification, and class IV and V cells were defined as malignant. RESULTS: Before washout, exfoliated cancer cells were found in 15 of 24 (62.5%) patients with rectal cancer and in 1 of 16 (6.2%) patients with sigmoid colon cancer (p < 0.001). Distal-free margin from the tumor was significantly shorter in patients with cancer cells (p = 0.002), and the length of the distal-free margin was significantly associated with the tumor location. After irrigation with 500 and 1,000 mL of saline, no cancer cell was found in all patients with sigmoid colon cancer, whereas ECCs were still found in five patients with rectal cancer (20.8%). CONCLUSIONS: Intraluminal washout with 1,000 mL may be sufficient for sigmoid colon cancer patients with longer distal-free margin. A large-scale, randomized controlled study is necessary to confirm these results.

Photodynamic therapy as salvage therapy for residual microscopic cancer after ultra-low anterior resection: A case report.

BACKGROUND: The rate of positive resection margins (R1) in patients with low rectal cancer is substantial. Recommended remedies such as extended resection or chemoradiotherapy have their own serious drawbacks. It has been reported that photodynamic therapy (PDT) as a remedial treatment for esophageal cancer. Colorectal cancer and esophageal cancer has many similarities, however, PDT as a salvage therapy for rectal cancer is rare. CASE SUMMARY: Here, we describe a 56-year-old man who was admitted to the hospital due to a 6-mo history of hemafecia, which had been aggravated for 1 mo. Colonoscopy revealed a 3 cm × 4 cm ulcerated mass in the rectum 4 cm from the anus. Preoperative pathological examination showed villous adenoma, moderate-to-high-grade dysplasia, good differentiation, and invasion of the mucosal muscle. The patient had R1 after ultra-low anterior resection, but he refused extended resection and experienced severe liver function impairment after 3 cycles of chemotherapy. Ultimately, the patient underwent PDT to remove R1. After five years of follow-up, there was no liver function impairment, recurrence, metastasis, sexual dysfunction, or abnormal defecation function. CONCLUSION: This is the first case worldwide in which R1 of rectal cancer were successfully treated by PDT.

Transanal Endoscopic Microsurgery Implementation in Ultra-Low Anterior Resection.

BACKGROUND: Distal rectal cancer resection is an ongoing challenge for the colorectal surgeon. In recent years new technical approaches, especially with implementation of transanal platforms were developed to help in the visualization and resection of these tumors. Nevertheless, the use of these platforms is demanding with significant complications during the onset phase. METHODS: Patients with very low rectal cancer were operated on in a single tertiary center with a combined abdominal and transanal endoscopic microsurgery (TEM) approach. Demographic, pathological, and surgical data were collected retrospectively with an emphasis on distal margin involvement. RESULTS: Nineteen patients were operated on during the study period. All patients had negative distal resection margins with a low complication rate. The distant metastasis and local recurrence rates were low with a mean follow-up of 2 years. CONCLUSIONS: TEM provides an appealing and viable option for the resection of low rectal cancer in a combined transabdominal and transanal approach in patients with a good response after neoadjuvant treatment. This is one of the available platforms a colorectal surgeon might benefit from having in his armamentarium. It has a very low complication rate with maintenance of oncological principles, enabling a clear visualization of the distal rectum, and thus ensures free distal resection margins.

Identification and Quantification of Drug-Resistant Cells in Colorectal Tumor and Distal Margin.

Cancer stem cells are cellular subpopulations in tumor, which are highly tumorigenic and drug resistant due to their adaptive molecular mechanism. In the recent years, these cells have attracted researchers' focus because of their unique properties which makes them biologically well evolved than other proliferating tumor cells. We have studied the presence of cancer stem cells in colorectal cancer (CRC) and its surgical margins. We report for the first time the presence of drug-resistant cells in distal resection margins in CRC and showed that a closer distal margin of less than 2 cm could have higher possibility of drug-resistant cells to spread.