Robotic resection of presacral tumors

BACKGROUND

Presacral tumors are a rare entity typically treated with an open surgical approach. A limited number of minimally invasive resections have been described. The aim of the study is to evaluate the safety and efficacy of roboticresection of presacral tumors.

METHODS

This is a retrospective single system analysis, conducted at a quaternary referral academic healthcare system, and included all patients who underwent a robotic excision of a presacral tumor between 2015 and 2023. Outcomes of interest were operative time, estimated blood loss, complications, length of stay, margin status, and recurrence rates.

RESULTS

Sixteen patients (11 females and 5 males) were included. The median age of the cohort was 51 years (range 25-69 years). The median operative time was 197 min (range 98-802 min). The median estimated blood loss was 40 ml, ranging from 0 to 1800 ml, with one patient experiencing conversion to open surgery after uncontrolled hemorrhage. Urinary retention was the only postoperative complication that occurred in three patients (19%) and was solved within 30 days in all cases. The median length of stay was one day (range 1-6 days). The median follow-up was 6.7 months (range 1-110 months). All tumors were excised with appropriate margins, but one benign and one malignant tumor recurred (12.5%). Ten tumors were classified as congenital (one was malignant), two were mesenchymal (both malignant), and five were miscellaneous (one malignant).

CONCLUSIONS

Robotic resection of select presacral pathology is feasible and safe. Further studies must be conducted to determine complication rates, outcomes, and long-term safety profiles.

The empty pelvis syndrome: a core data set from the PelvEx collaborative

BACKGROUND

Empty pelvis syndrome (EPS) is a significant source of morbidity following pelvic exenteration (PE), but is undefined. EPS outcome reporting and descriptors of radicality of PE are inconsistent; therefore, the best approaches for prevention are unknown. To facilitate future research into EPS, the aim of this study is to define a measurable core outcome set, core descriptor set and written definition for EPS. Consensus on strategies to mitigate EPS was also explored.

METHOD

Three-stage consensus methodology was used: longlisting with systematic review, healthcare professional event, patient engagement, and Delphi-piloting; shortlisting with two rounds of modified Delphi; and a confirmatory stage using a modified nominal group technique. This included a selection of measurement instruments, and iterative generation of a written EPS definition.

RESULTS

One hundred and three and 119 participants took part in the modified Delphi and consensus meetings, respectively. This encompassed international patient and healthcare professional representation with multidisciplinary input. Seventy statements were longlisted, seven core outcomes (bowel obstruction, enteroperineal fistula, chronic perineal sinus, infected pelvic collection, bowel obstruction, morbidity from reconstruction, re-intervention, and quality of life), and four core descriptors (magnitude of surgery, radiotherapy-induced damage, methods of reconstruction, and changes in volume of pelvic dead space) reached consensus-where applicable, measurement of these outcomes and descriptors was defined. A written definition for EPS was agreed.

CONCLUSIONS

EPS is an area of unmet research and clinical need. This study provides an agreed definition and core data set for EPS to facilitate further research.

Minimum standards of pelvic exenterative practice: PelvEx Collaborative guideline

This document outlines the important aspects of caring for patients who have been diagnosed with advanced pelvic cancer. It is primarily aimed at those who are establishing a service that adequately caters to this patient group. The relevant literature has been summarized and an attempt made to simplify the approach to management of these complex cases.

Simultaneous pelvic exenteration and liver resection for primary rectal cancer with synchronous liver metastases: results from the PelvEx Collaborative

AIM

At presentation, 15-20% of patients with rectal cancer already have synchronous liver metastases. The aim of this study was to determine the surgical and survival outcomes in patients with advanced rectal cancer who underwent combined pelvic exenteration and liver (oligometastatic) resection.

METHOD

Data from 20 international institutions that performed simultaneous pelvic exenteration and liver resection between 2007 and 2017 were accumulated. Primarily, we examined perioperative outcomes, morbidity and mortality. We also assessed the impact that margin status had on survival.

RESULTS

Of 128 patients, 72 (56.2%) were men with a median age of 60 years [interquartile range (IQR) 15 years]. The median size of the liver oligometastatic deposits was 2 cm (IQR 1.8 cm). The median duration of surgery was 406 min (IQR 240 min), with a median blood loss of 1090 ml (IQR 2010 ml). A negative resection margin (R0 resection) was achieved in 73.5% of pelvic exenterations and 66.4% of liver resections. The 30-day mortality rate was 1.6%, and 32% of patients had a major postoperative complication. The 5-year overall survival for patients in whom an R0 resection of both primary and metastatic disease was achieved was 54.6% compared with 20% for those with an R1/R2 resection (P = 0.006).

CONCLUSION

Simultaneous pelvic exenteration and liver resection is feasible, with acceptable morbidity and mortality. Simultaneous resection should only be performed where an R0 resection of both pelvic and hepatic disease is anticipated.

Risk factors for conversion in laparoscopic and robotic rectal cancer surgery

BACKGROUND

The aim of this study was to review risk factors for conversion in a cohort of patients with rectal cancer undergoing minimally invasive abdominal surgery.

METHODS

A retrospective analysis was performed of consecutive patients operated on from February 2005 to April 2018. Adult patients undergoing low anterior resection or abdominoperineal resection for primary rectal adenocarcinoma by a minimally invasive approach were included. Exclusion criteria were lack of research authorization, stage IV or recurrent rectal cancer, and emergency surgery. Risk factors for conversion were investigated using logistic regression. A subgroup analysis of obese patients (BMI 30 kg/m² or more) was performed.

RESULTS

A total of 600 patients were included in the analysis. The overall conversion rate was 9·2 per cent. Multivariable analysis showed a 72 per cent lower risk of conversion when patients had robotic surgery (odds ratio (OR) 0·28, 95 per cent c.i. 0·15 to 0·52). Obese patients experienced a threefold higher risk of conversion compared with non-obese patients (47 versus 24·4 per cent respectively; P < 0·001). Robotic surgery was associated with a reduced risk of conversion in obese patients (OR 0·22, 0·07 to 0·71).

CONCLUSION

Robotic surgery was associated with a lower risk of conversion in patients undergoing minimally invasive rectal cancer surgery, in both obese and non-obese patients.

Identification of patients eligible for discharge within 48 h of colorectal resection

BACKGROUND

This study aimed to identify patients eligible for a 48-h stay after colorectal resection, to provide guidance for early discharge planning.

METHODS

A bi-institutional retrospective cohort study was undertaken of consecutive patients undergoing major elective colorectal resection for benign or malignant pathology within a comprehensive enhanced recovery pathway between 2011 and 2017. Overall and severe (Clavien-Dindo grade IIIb or above) postoperative complication and readmission rates were compared between patients who were discharged within 48 h and those who had hospital stay of 48 h or more. Multinominal logistic regression analysis was performed to ascertain significant factors associated with a short hospital stay (less than 48 h).

RESULTS

In total, 686 of 5122 patients (13·4 per cent) were discharged within 48 h. Independent factors favouring a short hospital stay were age below 60 years (odds ratio (OR) 1·34; P = 0·002), ASA grade less than III (OR 1·42; P = 0·003), restrictive fluid management (less than 3000 ml on day of surgery: OR 1·46; P < 0·001), duration of surgery less than 180 min (OR 1·89; P < 0·001), minimally invasive approach (OR 1·92; P < 0·001) and wound contamination grade below III (OR 4·50; P < 0·001), whereas cancer diagnosis (OR 0·55; P < 0·001) and malnutrition (BMI below 18 kg/m² : OR 0·42; P = 0·008) decreased the likelihood of early discharge. Patients with a 48-h stay had fewer overall (10·8 per cent versus 30·6 per cent in those with a longer stay; P < 0·001) and fewer severe (2·6 versus 10·2 per cent respectively; P < 0·001) complications, and a lower readmission rate (9·0 versus 11·8 per cent; P = 0·035).

CONCLUSION

Early discharge of selected patients is safe and does not increase postoperative morbidity or readmission rates. In these patients, outpatient colorectal surgery should be feasible on a large scale with logistical optimization.

Comparison of recovery and outcome after left and right colectomy

AIM

The present study aimed to compare functional recovery and surgical outcomes after left and right colectomies.

METHOD

Consecutive elective left and right colon resections for benign and malignant indications, performed between 2011 and 2016 and recorded in a prospectively maintained enhanced recovery database, were analysed. Demographic and surgical items, as well as functional recovery and 30-day complications, were compared between left-sided and right-sided colectomies. Multivariable analysis was performed to identify risk factors for postoperative ileus (POI).

RESULTS

In total, 1001 left and 1041 right colectomies were comparable regarding demographic factors; only body mass index (BMI) was higher in patients undergoing left-sided resections (> 30 kg/m² : 33% vs 27%, P = 0.004). Malignancy (29% vs 67%, P < 0.001) and Crohn's disease (1% vs 31%, P < 0.001) were preponderant in right colectomies, whereas diverticular disease (68% vs 1%, P < 0.001) was the most common indication for left colectomy. Compliance with the enhanced recovery pathway (ERP) was comparable. While the minimally invasive approach was the preferred approach for both sides (61% vs 64%, P = 0.158), left colectomies took longer (180 ± 80 min vs 150 ± 70 min, P < 0.001), needed more perioperative fluids (3.1 ± 1.4 l vs 2.7 ± 1.5 l, P < 0.001) and resulted in greater postoperative weight gain (3.9 ± 6.5 kg vs 2.6 ± 6 kg, P = 0.025). Crohn's disease (OR = 2.64, 95% CI: 1.27-5.46) and fluid overload (OR = 2.02, 95% CI: 1.06-3.82) were independent risk factors for POI.

CONCLUSION

Despite equal ERP compliance, postoperative ileus was higher after right-sided colectomies. This finding was associated with Crohn's disease and fluid overload.

Randomized clinical trial of liposomal bupivacaine transverse abdominis plane block versus intrathecal analgesia in colorectal surgery

Background

Transverse abdominis plane (TAP) block is considered an effective alternative to neuraxial analgesia for abdominal surgery. However, limited evidence supports its use over traditional analgesic modalities in colorectal surgery. This study compared the analgesic efficacy of liposomal bupivacaine TAP block with intrathecal (IT) opioid administration in a multicentre RCT.

Methods

Patients undergoing elective small bowel or colorectal resection were randomized to receive TAP block or a single injection of IT analgesia with hydromorphone. Patients were assessed at 4, 8, 16, 24 and 48 h after surgery. Primary outcomes were mean pain scores and morphine milligram equivalents (MMEs) administered within 48 h after surgery. Secondary outcomes included duration of hospital stay, incidence of postoperative ileus and use of intravenous patient-controlled analgesia.

Results

In total, 209 patients were recruited and 200 completed the trial (TAP 102, IT 98). The TAP group had a 1·6-point greater mean pain score than the IT group at 4 h after surgery, and this difference lasted for 16 h after operation. The TAP group received more MMEs within the first 24 h after surgery than the IT group (median difference in MMEs 10·0, 95 per cent c.i. 3·0 to 20·5). There were no differences in MME use at 24 and 48 h, or with respect to secondary outcomes.

Conclusion

IT opioid administration provided better immediate postoperative pain control than TAP block. Both modalities resulted in low pain scores in patients undergoing elective colorectal surgery and should be considered in multimodal postoperative analgesic plans. Registration number: NCT02356198 ( http://www.clinicaltrials.gov).

Impact of enhanced recovery on oncological outcomes following minimally invasive surgery for rectal cancer

BACKGROUND

Oncological outcomes of locally advanced rectal cancer depend on the quality of surgical and oncological management. Enhanced recovery pathways (ERPs) have yet to be assessed for their oncological impact when used in combination with minimally invasive surgery. This study assessed outcomes with or without an ERP in patients with rectal cancer.

METHODS

This was a retrospective analysis of all consecutive adult patients who underwent elective minimally invasive surgery for primary rectal adenocarcinoma with curative intent between February 2005 and April 2018. Both laparoscopic and robotic procedures were included. Short-term morbidity and overall survival were compared between patients treated according to the institutional ERP and those who received conventional care.

RESULTS

A total of 600 patients underwent minimally invasive surgery, of whom 320 (53·3 per cent) were treated according to the ERP and 280 (46·7 per cent) received conventional care. ERP was associated with less overall morbidity (34·7 versus 54·3 per cent; P < 0·001). Patients in the ERP group had improved overall survival on univariable (91·4 versus 81·7 per cent at 5 years; hazard ratio (HR) 0·53, 95 per cent c.i. 0·28 to 0·99) but not multivariable (HR 0·78, 0·41 to 1·50) analysis. Multivariable analysis revealed age (HR 1·46, 1·17 to 1·82), male sex (HR 1·98, 1·05 to 3·70) and complications (HR 2·23, 1·30 to 3·83) as independent risk factors for compromised overall survival. Disease-free survival was comparable for patients who had ERP or conventional treatment (80·5 versus 84·6 per cent at 5 years respectively; P = 0·272).

CONCLUSION

Treatment within an ERP was associated with a lower morbidity risk that may have had a subtle impact on overall but not disease-specific survival.

Does obesity impact postoperative outcomes following robotic-assisted surgery for rectal cancer?

INTRODUCTION

Obesity has been identified as a risk factor for both conversion and severe postoperative morbidity in patients undergoing laparoscopic rectal resection. Robotic-assisted surgery (RAS) is proposed to overcome some of the technical limitations associated with laparoscopic surgery for rectal cancer. The aim of our study was to determine if obesity remains a risk factor for severe morbidity in patients undergoing robotic-assisted rectal resection.

PATIENTS

This study was a retrospective review of a prospective database. A total of 183 patients undergoing restorative RAS for rectal cancer between 2007 and 2016 were divided into 2 groups: control (BMI < 30 kg/m²; n = 125) and obese (BMI ≥ 30 kg/m²; n = 58). Clinicopathologic data, 30-day postoperative morbidity, and perioperative outcomes were compared between groups. The main outcome was severe postoperative morbidity defined as any complication graded Clavien-Dindo ≥ 3.

RESULTS

Control and obese groups had similar clinicopathologic characteristics. Severe complications were observed in 9 (7%) and 4 (7%) patients, respectively (p > 0.99). Obesity did not impact conversion, anastomotic leak rate, length of stay, or readmission but was significantly associated with increased postoperative morbidity (29 vs. 45%; p = 0.04) and especially more postoperative ileus (11 vs. 26%; p = 0.01). Obesity and male gender were the two independent risk factors for postoperative overall morbidity (OR 1.97; 95% CI 1.02-3.94; p = 0.04 and OR 2.23; 95% CI 1.10-4.76; p = 0.03, respectively).

CONCLUSION

‎Obesity did not impact severe morbidity or conversion rate following RAS for rectal cancer but remained a risk factor for overall morbidity and especially postoperative ileus.

Prognostic value of pathological node status after neoadjuvant radiotherapy for rectal cancer

Background

The prognostic value of pathological lymph node status following neoadjuvant radiotherapy (ypN) remains unclear. This study was designed to determine whether ypN status predicted overall survival.

Methods

Patients with locally advanced rectal adenocarcinoma who underwent neoadjuvant long-course radiation between 2005 and 2014 were identified from the National Cancer Data Base, and divided into ypN0, ypN1 and ypN2 groups. The primary outcome was overall survival. Univariable and multivariable analyses were used to determine factors associated with overall survival.

Results

Of 12 271 patients, 3713 (30·3 per cent) were found to have residual nodal positivity. A majority of patients with ypN1 (1663 of 2562) and ypN2 (878 of 1151) disease had suspected lymph node-positive disease before neoadjuvant therapy, compared with 3959 of 8558 with ypN0 tumours (P &lt; 0·001). Moreover, ypN1 and ypN2 were significantly associated with ypT3–4 disease (65·7 and 83·0 per cent respectively versus 39·4 per cent for ypN0; P &lt; 0·001). In unadjusted analyses, survival differed significantly between ypN groups (P &lt; 0·001). Five-year survival rates were 81·6, 71·3 and 55·0 per cent for patients with ypN0, ypN1 and ypN2 disease respectively. After adjustment for confounding variables, ypN1 and ypN2 remained independently associated with overall survival: hazard ratio (HR) 1·61 (95 per cent c.i. 1·46 to 1·77) and 2·63 (2·34 to 2·95) respectively (P &lt; 0·001). Overall survival was significantly longer in patients with ypN1–2 combined with ypT0–2 status than among those with ypT3–4 tumours even with ypN0 status (P = 0·031). Clinical nodal status before neoadjuvant therapy was not significantly associated with overall survival (HR 1·05, 0·97 to 1·13; P = 0·259).

Conclusion

Both ypT and ypN status is of prognostic significance following neoadjuvant therapy for rectal cancer.

Safety, feasibility, and short-term outcomes in 588 patients undergoing minimally invasive ileal pouch-anal anastomosis: a single-institution experience

PURPOSE

A laparoscopic approach to proctocolectomy and ileal pouch-anal anastomosis (IPAA) in patients with chronic ulcerative colitis and familial adenomatous polyposis has grown in popularity secondary to reports of small series demonstrating short-term patient benefits. Limited data exist in large numbers of patients undergoing laparoscopic ileal pouch-anal anastomosis (L-IPAA). We aimed to analyze surgical outcomes in a large cohort of patients undergoing L-IPAA.

METHODS

From a prospectively maintained surgical database, 30-day surgical outcome data were reviewed for all L-IPAA performed for chronic ulcerative colitis and familial adenomatous polyposis from 1999 to 2012. Demographics, operative approach, and operative and postoperative complications were analyzed.

RESULTS

A total of 588 L-IPAA ileal pouch-anal anastomoses were performed predominantly for chronic ulcerative colitis (93.9 %). The mean age was 36.2 years, and 54.3 % were male, with a mean BMI of 24.1 kg/m(2). Three-stage operations were performed in 17.7 %. The mean operating time of the patients excluding 3-stage operation was 269.4 min. Minimally invasive techniques included hand-assist in 55 % and straight laparoscopy in 45 %. Conversion to open occurred in 8.8 %. Median length of stay was 5 days. There was no mortality. Complications occurred in 36.9 % of patients: Clavien grade I (17.5 %), grade II (72.8 %), and grade III (9.7 %). Analysis of the grouped data over time demonstrated a statistically significant reduction in operative time (p < 0.001) and an increase in the ratio of hand-assisted over straight laparoscopy (p = 0.001).

CONCLUSIONS

Minimally invasive IPAA performed using either a laparoscopic or hand-assisted technique is safe, can be performed with low conversion rates, and confers beneficial perioperative outcomes.

Outcomes with multimodal therapy for elderly patients with rectal cancer

BACKGROUND

Treatment guidelines for stage II and III rectal cancer include neoadjuvant chemoradiotherapy, surgery and postoperative adjuvant chemotherapy. Although data support this recommendation in younger patients, it is unclear whether this benefit can be extrapolated to elderly patients (aged 75 years or older).

METHODS

This was a retrospective review of patients aged at least 75 years with stage II or III rectal cancer who underwent surgery with curative intent from 1996 to 2013 at the Mayo Clinic. Kaplan-Meier analysis and log rank test were used to compare overall survival between therapy groups. Cox proportional hazards model was used to estimate the independent effect of treatment group on survival.

RESULTS

A total of 160 elderly patients (median age 80 years) with stage II (66) and stage III (94) rectal cancer underwent surgical resection. Only 30·0 and 33·8 per cent received neoadjuvant or adjuvant therapy respectively. Among patients with stage II disease, there was no significant difference in 60-month survival between patients who received any additional therapy and those who had surgery alone (55 versus 38 per cent respectively; P = 0·184), whereas additional therapy improved survival in patients with stage III tumours (58 versus 30 per cent respectively; P = 0·007). Multivariable analysis found a survival benefit for additional therapy in elderly patients with stage III disease (hazard ratio 0·58, 95 per cent c.i. 0·34 to 0·98).

CONCLUSION

A multimodal approach in elderly patients with stage III rectal cancer improved oncological outcomes.

Outcomes after implementation of a multimodal standard care pathway for laparoscopic colorectal surgery

BACKGROUND

The aim of the study was to assess which aspects of an enhanced recovery programme are associated with better outcomes following laparoscopic colorectal surgery.

METHODS

A database of laparoscopic colorectal procedures performed in 2011 was reviewed. Elements of the enhanced recovery programme and compliance were evaluated for short-term (30-day) outcomes. Individual elements included gabapentin, celecoxib, intrathecal analgesia, diet, postoperative fluids, and paracetamol/non-steroidal anti-inflammatory drug pain management.

RESULTS

Five hundred and forty-one consecutive procedures were included. Compliance with the enhanced recovery programme elements ranged from 82.4 to 99.3 per cent. Median length of hospital stay was 3 (i.q.r. 2-5) days, with 25.9 per cent of patients discharged within 48 h. Patients without complications had a median length of stay of 3 (i.q.r. 2-4) days if compliant and 3 (3-5) days if not (P < 0.001). Low oral opiate intake (oral morphine equivalent of less than 30 mg) (odds ratio (OR) 1.97, 95 per cent confidence interval 1.29 to 3.03; P = 0.002), full compliance (OR 2.36, 1.42 to 3.90; P < 0.001) and high surgeon volume (more than 100 cases per year) (OR 1.50, 1.19 to 1.89; P < 0.001) were associated with discharge within 48 h. Compliance with the elements of oral intake and fluid management in the first 48 h was associated with a reduced rate of complications (8.1 versus 19.6 per cent; P = 0.001). Median oral opiate intake was 37.5 (i.q.r. 0-105) mg in 48 h, with 26.2 per cent of patients receiving no opiates.

CONCLUSION

Compliance with an enhanced recovery pathway was associated with less opiate use, fewer complications and a shorter hospital stay.

Impact of radiotherapy on surgical repair and outcome in patients with rectourethral fistula

AIM

Most patients presenting with rectourethral fistula acquire it as a complication of radiotherapy for prostate cancer, as a result of injury to the rectum during prostatectomy, through trauma or from Crohn's disease. This study examined whether choice of operation and results of surgery for rectourethral fistula are influenced by prior radiotherapy.

METHOD

Male patients undergoing surgery for rectourethral fistula were identified from a prospectively maintained database. Data regarding aetiology, surgical treatment and outcomes were analysed.

RESULTS

Fifty patients (median age = 65.5 years) were identified. Radiation was received by 29 patients for prostate or rectal cancer, and 21 patients developed a fistula following prostatectomy, Crohn's disease or pelvic fracture (without radiation). Prior to definitive surgery, 30 patients underwent fecal diversion and 37 underwent urinary diversion. In total, 57 repairs were performed (44 patients had one repair, five patients had two and one patient had three). Definitive surgery was approached predominantly abdominally in radiated patients (90.6 vs 9.3%, P < 0.001) and perineally in nonradiated patients (80 vs 20%, P < 0.001). Successful primary fistula repair was more frequent in the nonradiated group compared with the radiated group (80.9 vs 0%, P < 0.001). Permanent colostomy and urinary diversion were more often required in radiated patients than in nonradiated patients (colostomy: 83 vs 0%, P < 0.001; urorostomy: 100 vs 19%, P < 0.001).

CONCLUSION

Few patients with radiation-induced rectourethral fistula avoid permanent colostomy and urostomy. In contrast, most patients with nonradiation-related fistulae undergo successful perineal repair without permanent faecal and urinary diversion.

Distribution of TMEM100 in the mouse and human gastrointestinal tract--a novel marker of enteric nerves

Identification of markers of enteric neurons has contributed substantially to our understanding of the development, normal physiology, and pathology of the gut. Previously identified markers of the enteric nervous system can be used to label all or most neuronal structures or for examining individual cells by labeling just the nucleus or cell body. Most of these markers are excellent but have some limitations. Transmembrane protein 100 (TMEM100) is a gene at locus 17q32 encoding a 134-amino acid protein with two hypothetical transmembrane domains. TMEM100 expression has not been reported in adult mammalian tissues but does appear in the ventral neural tube of embryonic mice and plays a role in signaling pathways associated with development of the enteric nervous system. We showed that TMEM100 messenger RNA is expressed in the gastrointestinal tract and demonstrated that TMEM100 is a membrane-associated protein. Furthermore TMEM100 immunoreactivity was restricted to enteric neurons and vascular tissue in the muscularis propria of all regions of the mouse and human gastrointestinal tract. TMEM100 immunoreactivity colocalized with labeling for the pan-neuronal marker protein gene product 9.5 (PGP9.5) but not with the glial marker S100ß or Kit, a marker of interstitial cells of Cajal. The signaling molecule, bone morphogenetic protein (BMP) 4, was also expressed in enteric neurons of the human colon and co-localized with TMEM100. TMEM100 is also expressed in neuronal cell bodies and fibers in the mouse brain and dorsal root ganglia. We conclude that TMEM100 is a novel, membrane-associated marker for enteric nerves and is as effective as PGP9.5 for identifying neuronal structures in the gastrointestinal tract. The expression of TMEM100 in the enteric nervous system may reflect a role in the development and differentiation of cells through a transforming growth factor β, BMP or related signaling pathway.

Assembly of high-areal-density deuterium-tritium fuel from indirectly driven cryogenic implosions

The National Ignition Facility has been used to compress deuterium-tritium to an average areal density of ~1.0±0.1 g cm(-2), which is 67% of the ignition requirement. These conditions were obtained using 192 laser beams with total energy of 1-1.6 MJ and peak power up to 420 TW to create a hohlraum drive with a shaped power profile, peaking at a soft x-ray radiation temperature of 275-300 eV. This pulse delivered a series of shocks that compressed a capsule containing cryogenic deuterium-tritium to a radius of 25-35 μm. Neutron images of the implosion were used to estimate a fuel density of 500-800 g cm(-3).

Outcomes following surgery without radiotherapy for rectal cancer

BACKGROUND

This study determined survival and recurrence rates following curative resection of rectal cancer without radiotherapy.

METHODS

This was a retrospective review of the Mayo Clinic database of patients with rectal cancer treated with curative intent using surgery alone from 1990 to 2006. Patients who received neoadjuvant chemotherapy or radiation therapy and those who had any postoperative radiotherapy were excluded. Details were collected from the database and patient records using a protocol approved by the institutional review board.

RESULTS

Some 655 consecutive patients with rectal cancer treated with curative intent using surgery alone were identified; 397 had stage I disease, 125 stage II and 133 stage III. Four hundred and nine patients underwent anterior resection (AR) and 246 abdominoperineal resection (APR). Median follow-up was 62 months. The 5-year rate of local recurrence was 4·3 per cent, disease-free survival 90·0 per cent and cancer-specific survival 91·5 per cent. Stage-specific and all-stage disease-free survival did not differ significantly between AR and APR. The 5-year cumulative local recurrence rate was lower following AR than APR (3·6 versus 5·5 per cent; P = 0·321). There were only two patients with positive margins and type of operation was not significant on multivariable analysis.

CONCLUSION

Well-performed, standardized APRs have similar local recurrence to AR. Radiation therapy may not confer much additional benefit.

Case-matched series of enhanced versus standard recovery pathway in minimally invasive colorectal surgery

BACKGROUND

Accelerated recovery pathways may reduce length of hospital stay after surgery but there are few data on minimally invasive colorectal operations.

METHODS

An enhanced recovery pathway (ERP) was instituted, including preoperative analgesia, limited intravenous fluids and opiates, and early feeding. Intrathecal analgesia was administered as needed, but epidural analgesia was not used. The first 66 patients subjected to the ERP were case-matched by surgeon, procedure and age (within 5 years) with patients treated previously in a fast-track pathway (FTP). Short-term and postoperative outcomes to 30 days were compared.

RESULTS

Hospital stay was shorter with the ERP than the FTP: median (interquartile range, i.q.r.) 3 (2-3) versus 3 (3-5) days (P < 0·001). A 2-day hospital stay was achieved in 44 and 8 per cent of patients respectively (P < 0·001). Patients in the ERP had a shorter time to recovery of bowel function: median (i.q.r.) 1 (1-2) versus 2 (2-3) days (P < 0·001). Thirty-day complication rates were similar (32 per cent ERP, 27 per cent FTP; P = 0·570). Readmissions within 30 days were more common with ERP, but the difference was not statistically significant (10 versus 5 patients; P = 0·170). Total hospital stay for those readmitted was shorter in the ERP group (18 versus 23 days).

CONCLUSION

ERP decreased the length of hospital stay after minimally invasive colorectal surgery.

Endoscopic and surgical management of serrated colonic polyps

BACKGROUND

Serrated polyps are an inhomogeneous group of lesions that harbour precursors of colorectal cancer. Current research has been directed at further defining the histopathological characteristics of these lesions, but definitive treatment recommendations are unclear. The aim was to review the current literature regarding classification, molecular genetics and natural history of these lesions in order to propose a treatment algorithm for surgeons to consider.

METHODS

The PubMed database was searched using the following search terms: serrated polyp, serrated adenoma, hyperplastic polyp, hyperplastic polyposis, adenoma, endoscopy, surgery, guidelines. Papers published between 1980 and 2010 were selected.

RESULTS

Sixty papers met the selection criteria. Most authors agree that recommendations regarding endoscopic or surgical management should be based on the polyp's neoplastic potential. Polyps greater than 5 mm should be biopsied to determine their histology so that intervention can be directed accurately. Narrow-band imaging or chromoendoscopy may facilitate the detection and assessment of extent of lesions. Complete endoscopic removal of sessile serrated adenomas in the left or right colon is recommended. Follow-up colonoscopy is recommended in 2-6 months if endoscopic removal is incomplete. If the lesion cannot be entirely removed endoscopically, segmental colectomy is strongly recommended owing to the malignant potential of these polyps. Left-sided lesions are more likely to be pedunculated, making them more amenable to successful endoscopic removal.

CONCLUSION

Even though the neoplastic potential of certain subtypes of serrated polyp is heavily supported, further studies are needed to make definitive endoscopic and surgical recommendations.

Demonstration of ignition radiation temperatures in indirect-drive inertial confinement fusion hohlraums

We demonstrate the hohlraum radiation temperature and symmetry required for ignition-scale inertial confinement fusion capsule implosions. Cryogenic gas-filled hohlraums with 2.2 mm-diameter capsules are heated with unprecedented laser energies of 1.2 MJ delivered by 192 ultraviolet laser beams on the National Ignition Facility. Laser backscatter measurements show that these hohlraums absorb 87% to 91% of the incident laser power resulting in peak radiation temperatures of T(RAD)=300 eV and a symmetric implosion to a 100 μm diameter hot core.

Short-term outcomes after elective minimally invasive colectomy for diverticulitis

BACKGROUND

The role of minimally invasive surgery in complicated diverticulitis is still being elucidated. The aim of this study was to compare short-term outcomes in patients undergoing minimally invasive surgery for complicated or uncomplicated diverticular disease.

METHODS

All patients who had elective minimally invasive surgery for diverticulitis between 2003 and 2008 were identified from a prospectively maintained database. Complicated disease was defined as diverticulitis associated with abscess, fistula, stricture or bleeding. Univariable analysis was performed to compare safety and short-term outcomes in patients with complicated and uncomplicated diverticulitis.

RESULTS

A total of 361 patients (136 with complicated and 225 with uncomplicated diverticulitis) were operated on with either a laparoscopic (36·0 per cent) or a hand-assisted laparoscopic (64·0 per cent) surgical technique. There were no significant differences between the groups with respect to age, sex, body mass index, laparoscopic approach, postoperative recovery protocol or previous open surgery. Conversion rates were similar for complicated and uncomplicated disease (14·0 versus 11·6 per cent respectively; P = 0·514). There was no difference between the groups with respect to return of bowel function (mean 3·1 versus 3·2 days respectively; P = 0·156), morbidity (27·9 versus 19·6 per cent; P = 0·070) or mean length of stay (5·4 versus 4·8 days; P = 0·186). There were no deaths within 30 days.

CONCLUSION

Elective minimally invasive colectomy is feasible for patients with uncomplicated and complicated diverticulitis, with equivalent outcomes.

Malignant risk and surgical outcomes of presacral tailgut cysts

BACKGROUND

Presacral tailgut cysts are uncommon and few data exist on the outcomes following surgery.

METHODS

Patients undergoing tailgut cyst resection at the Mayo Clinic between 1985 and 2008 were analysed retrospectively. Demographic data, clinicopathological features, operative details, postoperative complications and recurrence were reviewed.

RESULTS

Thirty-one patients were identified (28 women), with a median age of 52 years. Seventeen patients were symptomatic and 28 had a palpable mass on digital rectal examination. Median cyst diameter was 4.4 cm. Four patients had a fistula to the rectum. Complete cyst excision was achieved in all patients; eight underwent distal sacral resection or coccygectomy. Postoperative complications occurred in eight patients but without 30-day mortality. Malignant transformation was present in four patients: adenocarcinoma in three and carcinoid in one. The cyst recurred in one patient after surgery for a benign lesion.

CONCLUSION

Presacral tailgut cysts should be removed due to the risk of malignant transformation.

Multimodality salvage therapy for anal cancer failing standard chemoradiation

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Background: Most squamous cell carcinomas of the anal canal (SCC) respond to chemoradiation, but effective therapy for locally-invasive(T4) or recurrent disease that fails standard chemoradiation and/or salvage abdominoperineal resection (APR) has not been clearly delineated. A multimodality approach including chemoradiation, extended pelvic resection and intraoperative radiation therapy (IORT) was assessed for survival impact and treatment morbidity.morbidities. Methods: A prospective registry including 26 patients with locally-invasive or recurrent disease treated between 1993 and 2007 was reviewed. Primary endpoint was overall survival (OS), obtained from prospectively collected patient questionnaires and medical record review, and analyzed by the Kaplan-Meier method. Short (60-day postoperative) and long-term (median followup: 1.6 years; 5.3 years among survivors) complications were assessed. Results: Patients (median age: 51 years) presented with (1) locally-invasive disease that persisted despite initial standard chemoradiation (n=10, 39%), (2) disease that recurred after initial standard chemoradiation (n=10, 39%; median 1.7 years to recurrence), or (3) re-recurrence after a salvage APR (n=6, 23%; median 1.3 years since APR). All patients received chemotherapy and external beam radiation preoperatively, and 19% received additional postoperative chemoradiation. Gross pelvic disease was completely resected in all (R0 in 73%; R1 in 27%). IORT (750–3250cGy) was delivered at single (92%) or two sites (8%). Median overall survival (OS) was 1.7 years. Five-year OS were: 50%, 10%, and 22% for patients with locally-invasive, recurrent, and re-recurrent disease respectively. Short-term complications predominantly related to the perineal wound. Fifteen patients reported long-term complications (>grade3): bowel obstruction in 8 (1 requiring operation), perineal wound fistula/non-healing in 9, leg paresthesia in 5, hydronephrosis in 3. Conclusions: For select patients with locally-persistent or recurrent SCC who fail standard primary treatment, a multimodality approach involving chemoradiation, extended pelvic resection and IORT offers a chance for improved survival.

No significant financial relationships to disclose.

Transvaginal colonic extraction following combined hysterectomy and laparoscopic total colectomy: a natural orifice approach

A major advantage of laparoscopic colectomy is the limited incision. We describe an innovative technique in which the entire colon is extracted transvaginally to avoid any abdominal extraction incision in a female patient with hereditary nonpolyposis colon cancer who required total colectomy and hysterectomy. This novel technical approach is feasible and safe, eliminates the need for any extraction abdominal incision, and may be considered in patients requiring concurrent abdominal colectomy and hysterectomy.

Ileal pouch-anal anastomosis and liver transplantation for ulcerative colitis complicated by primary sclerosing cholangitis

BACKGROUND

The aim was to evaluate outcomes in patients with ulcerative colitis complicated by primary sclerosing cholangitis (PSC) who required ileal pouch-anal anastomosis (IPAA) and orthotopic liver transplantation (OLT).

METHODS

A retrospective analysis was performed of 32 patients undergoing both IPAA and OLT between 1980 and 2006. Data were collected regarding demographics, indication for surgery, postoperative complications, and outcome of IPAA and OLT.

RESULTS

Thirty-day mortality after either procedure was nil. The median preoperative Model for End-stage Liver Disease (MELD) score for the group with initial IPAA was 8 (range 6-20) and the postoperative score was 11 (range 6-19). At 1 and 10 years, 32 and 26 of the 32 liver grafts had survived, and 31 and 30 of the 32 pouches, respectively. Fourteen patients require daily medical therapy for chronic pouchitis. At a median follow-up of 3.6 (range 0.2-16.2) years after the second of two procedures, responding patients reported a median of 5.5 stools per day and 2 stools per night.

CONCLUSION

IPAA and OLT are feasible and safe in patients requiring both procedures for ulcerative colitis and PSC. Functional outcomes are stable over time, despite an increased risk of chronic pouchitis.

Surgical management of intestinal malrotation in adults: comparative results for open and laparoscopic Ladd procedures

BACKGROUND

This study aimed to characterize the clinical features of intestinal malrotation in adults, and to compare the results for the open and laparoscopic Ladd procedures.

METHODS

Between 1984 and 2003, 21 adult patients with a mean age of 36 years (range, 14-89 years) were surgically treated for intestinal malrotation. The clinical data collected included age, gender, presenting symptoms, diagnostic tests, type of operation, operative time, narcotic requirement, time to oral intake, length of hospital stay, and outcome. The groups (open vs laparoscopic) were comparatively analyzed using two-sample t-tests and Wilcoxon rank sum tests.

RESULTS

The two groups were similar in terms of age, clinical presentation, and diagnostic tests performed. The most common presenting symptoms were chronic abdominal pain, nausea, and repeated vomiting. Upper gastrointestinal barium studies (UGI/SBFT) were diagnostic for all patients with malrotation as compared with computed tomography (CT) scanning, which was falsely negative in 25% of patients. A total of 21 patients underwent the Ladd procedure, either open (n = 10) or laparoscopic (n = 11). Three laparoscopic procedures were converted to open. Overall, the laparoscopic group resumed oral intake earlier than the open group (1.8 vs 2.7 days; p = 0.092), had a shorter hospital stay (4.0 vs. 6.1 days; p = 0.050), and required less intravenous narcotics on postoperative day 1 (4.9 vs 48.5 mg; p = 0.002). The laparoscopic group underwent a longer operation (194 vs 143 min; p = 0.053). Sixteen of eighteen patients available for follow-up reported complete resolution of symptoms, 2 felt greatly improved. No patient required a second operation related to volvulus or recurrent symptoms.

CONCLUSIONS

The laparoscopic Ladd procedure is feasible, safe, and as effective as the standard open Ladd procedure for the treatment of adults who have intestinal malrotation without midgut volvulus. Patients also benefit from this minimally invasive approach, as manifested by an earlier oral intake, a decreased need for intravenous narcotics, and an earlier discharge from the hospital.

Total laparoscopic proctocolectomy with Brooke ileostomy: a novel incisionless surgical treatment for patients with ulcerative colitis

BACKGROUND

This report describes the clinical benefits and safety of a novel (incisionless) laparoscopic operation for chronic ulcerative colitis.

METHODS

The medical records for four patients with the diagnosis of chronic ulcerative colitis who underwent "incisionless" laparoscopic proctocolectomy with Brooke ileostomy were reviewed. A novel technique was used for successfully performance of four total proctocloectomies with end ileostomies that did not require abdominal incisions. The clinical outcomes measured included time to oral intake, time to ostomy output, operative time, postoperative and intraoperative complications, estimated blood loss, and length of stay.

RESULTS

All the patients recovered without incident intraoperatively and postoperatively. The operative times ranged from 330 to 550 min. Postoperative findings included median time to oral intake (2 days), median time to ileostomy output (2 days), and median length of stay (4 days).

CONCLUSION

This case series demonstrates that an incisionless approach to chronic ulocerative colitis for patients who desire an end ileostomy may be feasible and safe, offering patients short-term recovery and cosmetic benefits.

Laparoscopic surgery for colorectal cancer: the state of the art

Laparoscopic techniques have expanded since their introduction 15 years ago. The laparoscopic approach for colorectal surgery has been slower to develop than other fields of surgery. However, this approach does provide significant benefits for colorectal resection, although concerns regarding the ability to satisfy oncological criteria have restricted its use in the past. This review studies the published data on the use of laparoscopic surgery for colorectal cancer including the short- and long-term outcomes. New long-term outcome data is now available which is likely to encourage the use of this technique for colon cancer resection. Laparoscopic rectal cancer resection is also discussed including the more limited outcome data that is available.

The paradox of great longevity in a short-lived tree species

Thuja occidentalis is a tree species that was once thought to be relatively short-lived (80 years). Up until 10 years ago maximum ages were considered to be near 400 years, but such trees were thought to be rare. Research along the cliffs of the Niagara Escarpment has altered this view. Exceptionally slow-growing trees of this species have been found with ring counts to 1653 years and estimated ages to 1890 years. Senescence is slow or absent. Injury and death is due to rockfall and sporadic severe drought that kills small sectors of the trees by exposing and killing the roots. Experiments in which colored dyes are infused into roots show that each tree is composed of hydraulically independent units that allow mortality in one part of the 'individual' with little negative effect on the remaining parts of the tree. The trees are small, so environmental loadings of ice, snow, and wind are low. Slow growth of the trees results in a much greater mechanical strength in the wood. Together these properties increase the ability of the cedars to persist on cliffs for long periods of time. The paradox of great longevity in this 'short-lived' tree species is explained by slow growth that minimizes maintenance and repair costs while maximizing durability and strength, combined with an internal architecture that creates functionally independent units within each tree.

Endolithic algae and cyanobacteria from cliffs of the Niagara Escarpment, Ontario, Canada

A comprehensive survey for endolithic organisms was undertaken to evaluate the distribution of endolithic algae and cyanobacteria in the structure of ancient cliff ecosystems of the Niagara Escarpment. Rocks were collected at 12 sites along the escarpment. Three rock samples were collected from each of five transects for a total of 180 rock samples. Cryptoendolithic or chasmoendolithic organisms were extracted from freshly cleaved faces under laboratory conditions, and attempts were made to culture, grow, and identify these organisms. Cultures of cryptoendolithic organisms were successfully obtained from between 6.7 and 40% of the culture plates from any one site, whereas chasmoendolithic organisms were obtained from 98% of the attempts. Twenty-two taxa were found, including some Cyanophyta that were present at most sites (Chlorogloea) and others that were found rarely (Schizothrix). Cyanophytes were more common at northern sites than southern sites. Among the Chlorophyta, Stichococcus bacillaris was ubiquitous, but Stichococcus exiguus was restricted to one site. The chlorophytes were evenly found along the Escarpment. No geographical trends were obvious among the Xanthophyceae, but some taxa such as Chloridella neglecta were common and others such as Ellipsoidion stichococcoides were not. These results suggest that endolithic organisms within the rocky limestone cliffs of the Niagara Escarpment are not uniform in abundance or species composition. Consequently, management plans intended to maintain microbial species diversity in the face of different patterns of land use and environmental pollution may have to be location-specific along the escarpment.Key words: terrestrial algae, cryptoendolithic organisms, cliffs, Niagara Escarpment.

Effects of natural habitat fragmentation on the species richness, diversity, and composition of cliff vegetation

Plant species richness, diversity, and some aspects of species composition were measured on natural limestone cliff fragments of varying size within the Niagara Escarpment Biosphere Reserve, Canada. This information was collected because knowledge about how different components of community structure change in response to natural fragmentation may permit the prediction of the effects of future anthropogenic fragmentation. The number and relative abundance of vascular plant, bryophyte, and lichen species were determined on cliff fragments that varied in area from 185 to 126 000 m2. Latitude, aspect, percent available photosynthetically active radiation on the cliff face, distance from the nearest neighbouring cliff, and length of the nearest neighbouring cliff were also measured. Regression analysis was used to test for a significant relationship between fragment area and diversity of vascular plants, bryophytes, and lichens both separately and combined. Multiple regression with all subsets selection was used to find the best predictors of species richness from among all variables measured for the 21 cliff fragments. Multivariate analyses were used to study the effect of fragmentation on the structure of the vegetation as a whole. The results showed no significant relationship between cliff fragment area and richness or diversity for vascular plants and bryophytes, and only a marginally significant increase in richness with area for lichens. The multivariate analyses also showed that only one community type exists, and that its structure mainly varies as a function of latitude. These results indicate that very small fragments of cliff face can support a similar plant biodiversity as do large continuous portions of the Niagara Escarpment.Key words: habitat fragmentation, plant species richness, lichens, bryophytes, cliff vegetation.

Influence of cliffs on bird community diversity

Cliffs along the Niagara Escarpment in Ontario, Canada, support a long, narrow presettlement forest that includes three distinct geomorphic and vegetation zones: cliff edge, cliff face, and talus slope. This unique landform provides an opportunity to evaluate differences in bird communities between the escarpment and adjacent forest relative to habitat features. We sampled forest birds 12 times during the summer of 1994 in plots located in plateau forests, on talus slope, at cliff edges, and on cliff faces. Eleven habitat variables considered important to birds were also sampled in the plots. We arranged plots along six randomly spaced transects at a south site and a north site. Both sites had the consistent habitat heterogeneity considered important to birds. Bird species richness and composition responded to this heterogeneity, but differently at each site: plateau deciduous forests always had the lowest richness and the simplest species composition, whereas both cliff edges and talus slopes had a higher diversity of birds. Cliff faces had large numbers of species in the south but smaller numbers in the north. Escarpment zones form a habitat mosaic that supports many species not found in the adjacent forest and is consistent with the effect of habitat edge. The results suggest that cliffs represent a significant additive influence on avian biodiversity, even when the cliff is a very narrow component of the landscape.

The role of electrolyte in lesion size using an irrigated radiofrequency electrode

Multiple attempts have been made to eliminate atrial fibrillation by performing the surgical maze procedure with radiofrequency energy. Currently, this is limited because of the risk of atrial perforation and the lack of transmural penetration. Saline irrigation has been investigated as a method of radiofrequency cautery tip cooling to prevent rapid temperature and impedance rises, which have been shown to lead to perforation or decreased radiofrequency penetration after eschar formation. There are few data on the influence that different types of electrolyte irrigation solutions have on lesion depth. Using a novel hollow cautery pen, we infused either an electrolyte solution (0.9%, 3%, 14.6%, or 23.4% sodium chloride), a nonelectrolyte solution (1.5% glycine), or no irrigation to produce 819 lesions on 14 left ventricles in swine using radiofrequency energy (450+/-10 kHz) applied at two output settings (20 and 75 watts). The nonelectrolyte solution increased lesion depth compared with no infusion at 20 watts but produced shallower lesion depths compared with electrolyte solutions at 75 watts. Compared with the other electrolyte solutions, the 0.9% sodium chloride solution produced the deepest lesions (3.34+/-0.06 mm) at 75 watts (p < 0.001). As the concentration of electrolyte increased, lesion depth decreased unless generator output increased. Formation of eschar and tissue destruction was seen in the noninfusion and nonelectrolyte groups but not in the electrolyte group. A conductive media coupled with radiofrequency energy allowed for greater lesion depth than irrigated cooling with a nonelectrolyte solution or no irrigation. There was an inverse relationship between electrolyte concentration and lesion depth. We conclude that the concentration of electrolyte irrigant is an important consideration when choosing a solution to improve transmural penetration and decrease the risk of tissue destruction from radiofrequency energy.