Single-port robotic transanal minimally invasive surgery (SPR-TAMIS) approach to local excision of rectal tumors.

BACKGROUND: Trans-anal excision is the surgical treatment of choice for endoscopically unresectable rectal polyps, early rectal cancers, small carcinoid tumors, and other low-risk tumors. The single-port robotic (SPR) platform is the newest development in robotic surgery capable of performing trans-anal minimally invasive surgery (TAMIS). In theory, the single incision design would naturally lend itself to the size limitation of the anal canal, but in practice, this method has not been tested. Herein we describe the techniques and first reports of performing TAMIS using the SPR platform. TECHNIQUE: We describe in detail how to perform the SPR-TAMIS technique using lessons and experience gained from performing this on five patients who had endoscopically unresectable rectal polyps or T1 rectal cancers. Each patient was followed for a minimum of 30 days and was seen in clinic post-operatively. A retrospective chart review was performed to obtain information on technical success, anatomic measurements, and reported complications. RESULTS: The SPR TAMIS was successfully performed on all five patients without any reported complications. All underwent a non-piecemeal excision and had return of regular bowel function at 30-day follow-up. All patients were discharged from the hospital the same day as their operation. CONCLUSIONS: SPR-TAMIS is a novel, safe, and feasible procedure capable of achieving non-piecemeal resections of low-risk rectal tumors. Further study needs to be conducted to determine complication rates, functional and oncologic outcomes, and ensure the long-term safety profile.

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.

A spectrometer for ultrashort gamma-ray pulses with photon energies greater than 10 MeV.

We present a design for a pixelated scintillator based gamma-ray spectrometer for non-linear inverse Compton scattering experiments. By colliding a laser wakefield accelerated electron beam with a tightly focused, intense laser pulse, gamma-ray photons up to 100 MeV energies and with few femtosecond duration may be produced. To measure the energy spectrum and angular distribution, a 33 × 47 array of cesium-iodide crystals was oriented such that the 47 crystal length axis was parallel to the gamma-ray beam and the 33 crystal length axis was oriented in the vertical direction. Using an iterative deconvolution method similar to the YOGI code, modeling of the scintillator response using GEANT4 and fitting to a quantum Monte Carlo calculated photon spectrum, we are able to extract the gamma ray spectra generated by the inverse Compton interaction.

Ultrafast Imaging of Laser Driven Shock Waves using Betatron X-rays from a Laser Wakefield Accelerator.

Betatron radiation from laser wakefield accelerators is an ultrashort pulsed source of hard, synchrotron-like x-ray radiation. It emanates from a centimetre scale plasma accelerator producing GeV level electron beams. In recent years betatron radiation has been developed as a unique source capable of producing high resolution x-ray images in compact geometries. However, until now, the short pulse nature of this radiation has not been exploited. This report details the first experiment to utilize betatron radiation to image a rapidly evolving phenomenon by using it to radiograph a laser driven shock wave in a silicon target. The spatial resolution of the image is comparable to what has been achieved in similar experiments at conventional synchrotron light sources. The intrinsic temporal resolution of betatron radiation is below 100 fs, indicating that significantly faster processes could be probed in future without compromising spatial resolution. Quantitative measurements of the shock velocity and material density were made from the radiographs recorded during shock compression and were consistent with the established shock response of silicon, as determined with traditional velocimetry approaches. This suggests that future compact betatron imaging beamlines could be useful in the imaging and diagnosis of high-energy-density physics experiments.

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.