CRISPR/dCAS9-mediated DNA demethylation screen identifies functional epigenetic determinants of colorectal cancer.

BACKGROUND: Promoter hypermethylation of tumour suppressor genes is frequently observed during the malignant transformation of colorectal cancer (CRC). However, whether this epigenetic mechanism is functional in cancer or is a mere consequence of the carcinogenic process remains to be elucidated. RESULTS: In this work, we performed an integrative multi-omic approach to identify gene candidates with strong correlations between DNA methylation and gene expression in human CRC samples and a set of 8 colon cancer cell lines. As a proof of concept, we combined recent CRISPR-Cas9 epigenome editing tools (dCas9-TET1, dCas9-TET-IM) with a customized arrayed gRNA library to modulate the DNA methylation status of 56 promoters previously linked with strong epigenetic repression in CRC, and we monitored the potential functional consequences of this DNA methylation loss by means of a high-content cell proliferation screen. Overall, the epigenetic modulation of most of these DNA methylated regions had a mild impact on the reactivation of gene expression and on the viability of cancer cells. Interestingly, we found that epigenetic reactivation of RSPO2 in the tumour context was associated with a significant impairment in cell proliferation in p53-/- cancer cell lines, and further validation with human samples demonstrated that the epigenetic silencing of RSPO2 is a mid-late event in the adenoma to carcinoma sequence. CONCLUSIONS: These results highlight the potential role of DNA methylation as a driver mechanism of CRC and paves the way for the identification of novel therapeutic windows based on the epigenetic reactivation of certain tumour suppressor genes.

Complete Mesocolic Excision and D3 Lymphadenectomy versus Conventional Colectomy for Colon Cancer: A Systematic Review and Meta-Analysis.

BACKGROUNDS: Previous systematic reviews suggest that the implementation of 'complete mesocolon excision' (CME) for colon tumors entails better specimen quality but with limited long-term outcomes. We performed a meta-analysis to compare the pathological, perioperative, and oncological results of CME with conventional surgery (CS) in primary colon cancer. METHODS: Embase, MEDLINE and CENTRAL databases were searched using Medical Subject Headings for CME and D3 lymphadenectomy. The systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. RESULTS: A total of 18,989 patients from 27 studies were included. Postoperative complications were higher in the CME group (relative risk [RR] 1.13, 95% confidence interval [CI] 1.04-1.22, I2 = 0%), while no differences were observed in terms of anastomotic leak (I2 = 0%) or perioperative mortality (I2 = 49%). CME was associated with a higher number of lymph nodes harvested (I2 = 95%), distance to high tie (I2 = 65%), bowel length (I2 = 0%), and mesentery area (I2 = 95%). CME also had positive effects on 3- and 5-year overall survival (RR 1.09, 95% CI 1.04-1.15, I2 = 88%; and RR 1.05, 95% CI 1.02-1.08, I2 = 62%, respectively) and 3-year disease-free survival (RR 1.10, 95% CI 1.04-1.17, I2 = 22%), as well as decreased local (RR 0.35, 95% CI 0.24-0.51, I2 = 51%) and distant recurrences (RR 0.71, 95% CI 0.60-0.85, I2 = 34%). CONCLUSIONS: Limited evidence suggests that CME improves oncological outcomes with a higher postoperative adverse events rate but no increase in anastomotic leak rate or perioperative mortality, compared with CS.

Linfografía como opción diagnóstica y terapéutica en la fuga quilosa posoperatoria de cáncer colorrectal.

La fuga quilosa es una complicación muy poco frecuente tras la cirugía colorrectal. Se presenta el caso de un paciente de 70 años con neoplasia de recto medio intervenido de forma electiva tras un ciclo largo de neoadyuvancia mediante una resección anterior de recto por laparoscopia. El cuarto día de posoperatorio presentó un drenaje pélvico de aspecto quiloso y el día 13 se confirmó la fuga quilosa en la linfografía. Posteriormente el débito se redujo de forma rápida. La linfografía no solo es un método diagnóstico, sino que en el 35-70% de los casos puede también ser terapéutica.Chylous leakage is an extremely rare complication after colorectal surgery. We report the case of a 70 year-old male with a mid-rectal cancer who underwent a laparoscopic anterior resection of the rectum after long course neoadjuvant therapy. On postoperative day 4 the patient presented with chylous pelvic drainage, and a chylous leakage was proved by lymphography on postoperative day 13. Hereinafter, the drainage was drastically reduced. The lymphography is not only a diagnostic technique, but it can be also a therapeutic method in up to 35-70% of the cases.

Transanal Hartmann's colostomy reversal assisted by laparoscopy: outcomes of the first 10 patients.

INTRODUCTION: Restoration of intestinal continuity after Hartmann's procedure is a technically difficult surgery associated with significant morbidity and mortality. This study presents the short-term results of a new approach: a transanal Hartmann's colostomy reversal assisted by laparoscopy. METHOD: This is a retrospective analysis of data collected in one tertiary hospital, from October 2013 to November 2015. RESULTS: During the study period, there were ten cases of transanal Hartmann's reversal. Reasons for Hartmann's procedure were: complicated diverticulitis (4), anastomotic leak (3), and recto-sigmoid cancer (3). Rectal stump length was 10.4 ± 4.5 cm. Reconstruction was achieved in all patients. One low colorectal anastomosis was hand-sewn, the other 9 were stapled. Mean operative time was 204 ± 65 min. Diverting loop ileostomies were created in five patients and all were closed during the following year. One case required hand-assistance but there was no conversion to open surgery. Iatrogenic laparoscopic enterotomies occurred in four patients and all were repaired primarily without consequences. Three patients had a total of four post-operative complications: ileus (2), abdominal abscess and wound infection (1). None required reoperation. Mean length of stay was 7.2 ± 4.3 days. One required readmission. CONCLUSION: A transanal Hartmann's reversal assisted by laparoscopy is a new approach for a difficult surgery. It has the potential to be an additional tool in the case of hostile pelvises or with a rectal stump difficult to identify. The surgery remains challenging and indications need to be clarified.

Transanal total mesorectal excision: surgical technique description and outcomes.

Minimally invasive techniques (MIS) have been evolving quickly in colorectal surgery during the last two decades. Transanal total mesorectal excision (taTME) was developed as a combination of skills acquired from different MIS approaches such as Transanal Endoscopic Microsurgery (TEM), Transanal Minimally Invasive Surgery (TAMIS) and Natural Orifices Transluminal Endoscopic Surgery (NOTES). TaTME allows for a better visualization of surgical planes of dissection and achievement of rectal resection following oncologic principles. We here present the standardized taTME technique in use at the Hospital Clínic de Barcelona and our published outcomes in rectal cancer.

Transanal Total Mesorectal Excision for Rectal Cancer: Outcomes after 140 Patients.

BACKGROUND: The anatomic difficulties that we have to deal with in open surgery for rectal cancer have not been overcome with the laparoscopic approach. In the search for a solution, a change of concept arose: approaching the rectum from below. The main objectives of this study were to show the potential advantages of the hybrid transabdominal-transanal total mesorectal excision (taTME). This approach may improve quality of the mesorectal specimens. Second, proctectomy can be technically easier and more safely performed "down to up," which would result in shorter surgical times, lower conversion rates, and less morbidity. STUDY DESIGN: A prospective series of hybrid taTME was conducted from October 2011 to November 2014. RESULTS: During the study period, 140 procedures were performed. Mean operative time was 166 minutes. There were no conversions or intraoperative complications. Macroscopic quality assessment of the resected specimen was complete in 97.1% and nearly complete in 2.1%. Thirty-day morbidity was minor (Clavien-Dindo I + II) in 24.2% and major (Clavien-Dindo III + IV) in 10 %. No patient died within the first 30 days postsurgery (Clavien-Dindo V). The mean follow-up was 15 months, with a 2.3% local recurrence rate and a 7.6% rate of systemic recurrence. CONCLUSIONS: Pathologic analysis showed a very good macroscopic quality of TME specimens, which is the most important prognostic factor in rectal cancer. Intraoperative outcomes regarding conversion, surgical times, and intraoperative complications are very satisfactory. Short-term morbidity and oncologic outcomes are as good as in other laparoscopic TME series.

Minimal invasive surgery: NOSE and NOTES in ulcerative colitis.

BACKGROUND: In patients with ulcerative colitis (UC), laparoscopic pelvic dissection for IPAA is not always straightforward: often, a hand-assistance incision is used to complete the proctectomy, lengthening operative times. Hybrid NOSE and NOTES are emerging as an alternative approach to conventional laparoscopy. We believe that UC patients could benefit from this new hybrid approach in three ways: by easing the proctectomy as performed down to up, avoiding additional incisions and decreasing surgical times. We present the short-term outcomes of our series. METHODS: All patients with UC who required IPAA were enrolled in a single-arm prospective study (July 2011 to March 2014). A three-step procedure was performed. The first step: laparoscopic colectomy (with transanal removal of the colon) and temporary ileostomy. The second step: "down-to-up" proctectomy (with transanal removal of the rectum) and IPAA with a covering ileostomy. We combined simultaneously transanal and laparoscopic approach. The third step: ileostomy closure. Functional outcomes were assessed 3 months after third step. RESULTS: Eighteen patients were enrolled. Two patients are waiting to complete the second stage, and 16 underwent all surgical steps. Twelve have been evaluated with functional scores. For the first step, the mean operative time was 162.2 min (SD 40.5) and 170 min (SD 50.1) for the second one. The median hospital stay was 6 days (IQR 5-14.75) for the first step and 5.5 (IQR 5-9.75) for the second one. No major complications occurred. Twenty-four-hour defecation frequency was 5.5 per day (SD 1.7), 0.5 per night. Seventy-five percentage of patients may retain stools for more than 30 min; the mean value of Oresland score was 4.7 and Wexner score 1.4. CONCLUSIONS: This is a safe and feasible technique to treat UC patients with good short-term outcomes. Long-term outcomes and controlled trials are needed.

Transanal total mesorectal excision in rectal cancer: short-term outcomes in comparison with laparoscopic surgery.

OBJECTIVE: The aim of this study was to compare short-term results obtained with transanal total mesorectal excision (TME) and laparoscopic surgery. BACKGROUND: Transanal TME appears as an alternative in the treatment of rectal cancer and other rectal disease. Natural orifices transluminal endoscopic surgery using the rectum as access in colorectal surgery is intuitively better suited than other access routes. METHODS: All consecutive patients with middle or low rectal cancer submitted to surgery were included into a prospective cohort and treated by transanal TME assisted by laparoscopy. They were compared with a retrospective cohort of consecutive patients of identical characteristics treated by laparoscopic TME in the immediate chronological period. RESULTS: Thirty-seven patients were included in both study groups. No differences were observed between them with respect to baseline characteristics, thus emphasizing the comparability of both cohorts. Surgical time was higher in the laparoscopy group (252 ± 50 minutes) than in the transanal group (215 ± 60 minutes) (P < 0.01). Moreover, coloanal anastomosis was performed less frequently (16% vs 43%, respectively; P = 0.01) and distal margin was lower (1.8 ± 1.2 mm vs 2.7 ± 1.7 mm, respectively; P = 0.05) in the laparoscopy group than in the transanal one. Although there was no significant difference in 30-day postoperative complication rate (laparoscopy, 51% vs transanal, 32%; P = 0.16), early readmissions were more frequent in the laparoscopy group than in the transanal one (22% vs 6%, respectively; P = 0.03). CONCLUSIONS: Evaluation of short-term outcomes demonstrated that transanal TME is a feasible and safe technique associated with a shorter surgical time and a lower early readmission rate.