Diffuse reflectance spectroscopy for colorectal cancer surgical guidance: towards real-time tissue characterization and new biomarkers.

Colorectal cancer (CRC) is the third most common and second most deadly type of cancer worldwide, representing 11.3% of the diagnosed cancer cases and resulting in 10.2% (0.88 million) of the cancer related deaths in 2020. CRCs are typically detected at the late stage, which leads to high mortality and morbidity. Mortality and poor prognosis are partially caused by cancer recurrence and postoperative complications. Patient survival could be increased by improving precision in surgical resection using accurate surgical guidance tools based on diffuse reflectance spectroscopy (DRS). DRS enables real-time tissue identification for potential cancer margin delineation through determination of the circumferential resection margin (CRM), while also supporting non-invasive and label-free approaches for laparoscopic surgery to avoid short-term complications of open surgery as suitable. In this study, we have estimated the scattering properties and chromophore concentrations based on 2949 DRS measurements of freshly excised ex vivo specimens of 47 patients, and used this estimation to classify normal colorectal wall (CW), fat and tumor tissues. DRS measurements were performed with fiber-optic probes of 630 µm source-detector distance (SDD; probe 1) and 2500 µm SDD (probe 2) to measure tissue layers ∼0.5-1 mm and ∼0.5-2 mm deep, respectively. By using the 5-fold cross-validation of machine learning models generated with the classification and regression tree (CART) algorithm, we achieved 95.9 ± 0.7% sensitivity, 98.9 ± 0.3% specificity, 90.2 ± 0.4% accuracy, and 95.5 ± 0.3% AUC for probe 1. Similarly, we achieved 96.9 ± 0.8% sensitivity, 98.9 ± 0.2% specificity, 94.0 ± 0.4% accuracy, and 96.7 ± 0.4% AUC for probe 2.

Insights into Biochemical Sources and Diffuse Reflectance Spectral Features for Colorectal Cancer Detection and Localization.

Colorectal cancer (CRC) is the third most common and second most deadly type of cancer worldwide. Early detection not only reduces mortality but also improves patient prognosis by allowing the use of minimally invasive techniques to remove cancer while avoiding major surgery. Expanding the use of microsurgical techniques requires accurate diagnosis and delineation of the tumor margins in order to allow complete excision of cancer. We have used diffuse reflectance spectroscopy (DRS) to identify the main optical CRC biomarkers and to optimize parameters for the integration of such technologies into medical devices. A total number of 2889 diffuse reflectance spectra were collected in ex vivo specimens from 47 patients. Short source-detector distance (SDD) and long-SDD fiber-optic probes were employed to measure tissue layers from 0.5 to 1 mm and from 0.5 to 1.9 mm deep, respectively. The most important biomolecules contributing to differentiating DRS between tissue types were oxy- and deoxy-hemoglobin (Hb and HbO2), followed by water and lipid. Accurate tissue classification and potential DRS device miniaturization using Hb, HbO2, lipid and water data were achieved particularly well within the wavelength ranges 350-590 nm and 600-1230 nm for the short-SDD probe, and 380-400 nm, 420-610 nm, and 650-950 nm for the long-SDD probe.

Sarcopaenia, obesity, sarcopaenic obesity and outcomes following hepatic resection for colorectal liver metastases: a systematic review and meta-analysis.

BACKGROUND: Obesity is a risk factor for the development of colorectal cancer. Limited evidence exists about outcomes for obese patients undergoing hepatic resection for colorectal liver metastases (CRLM). Sarcopaenia is characterised by a decline in muscle function and muscle mass. It is associated with poorer outcomes for patients on chemotherapy, but there are limited data for sarcopaenic patients undergoing hepatic resection for CRLM. METHODS: Pubmed, Embase, Cochrane Central, Web of Science, SCOPUS, and CINAHL databases were searched for articles which were selected in accordance with PRISMA guidelines. Primary outcomes were overall survival (OS) and disease-free survival (DFS). A random effects meta-analysis was conducted. RESULTS: Thirteen studies were included incorporating 2936 patients. No significant difference was found between obese and non-obese patients in OS (HR 0.81, CI 0.47-1.39, p = 0.44) or DFS (HR 1.0, CI 0.99-1.01, p = 0.98). Sarcopaenia was associated with worse OS (HR 1.65, CI 1.10-2.48, p = 0.01), and increased major post operative complications (OR 1.91, CI 1.16-3.14, p = 0.01). Only one study examined outcomes for sarcopaenic obese patients. CONCLUSION: Limited evidence exists describing the impact of obesity and sarcopenia on outcomes following hepatic resection for CRLM. Obese patients do not have worse oncological outcomes, whereas sarcopaenia is associated with poorer long-term survival.

Colorectal microbiota after removal of colorectal cancer.

The colonic microbiome has been implicated in the pathogenesis of colorectal cancer (CRC) and intestinal microbiome alterations are not confined to the tumour. Since data on whether the microbiome normalises or remains altered after resection of CRC are conflicting, we studied the colonic microbiota of patients after resection of CRC. We profiled the microbiota using 16S rRNA gene amplicon sequencing in colonic biopsies from patients after resection of CRC (n = 63) in comparison with controls (n = 52), subjects with newly diagnosed CRC (n = 93) and polyps (i = 28). The colonic microbiota after surgical resection remained significantly different from that of controls in 65% of patients. Genus-level profiling and beta-diversity confirmed two distinct groups of patients after resection of CRC: one with an abnormal microbiota similar to that of patients with newly diagnosed CRC and another similar to non-CRC controls. Consumption levels of several dietary ingredients and cardiovascular drugs co-varied with differences in microbiota composition suggesting lifestyle factors may modulate differential microbiome trajectories after surgical resection. This study supports investigation of the colonic microbiota as a marker of risk for development of CRC.

Evaluation of wavelength ranges and tissue depth probed by diffuse reflectance spectroscopy for colorectal cancer detection.

Colorectal cancer (CRC) is the third most common type of cancer worldwide and the second most deadly. Recent research efforts have focused on developing non-invasive techniques for CRC detection. In this study, we evaluated the diagnostic capabilities of diffuse reflectance spectroscopy (DRS) for CRC detection by building 6 classification models based on support vector machines (SVMs). Our dataset consists of 2889 diffuse reflectance spectra collected from freshly excised ex vivo tissues of 47 patients over wavelengths ranging from 350 and 1919 nm with source-detector distances of 630-µm and 2500-µm to probe different depths. Quadratic SVMs were used and performance was evaluated using twofold cross-validation on 10 iterations of randomized training and test sets. We achieved (93.5 ± 2.4)% sensitivity, (94.0 ± 1.7)% specificity AUC by probing the superficial colorectal tissue and (96.1 ± 1.8)% sensitivity, (95.7 ± 0.6)% specificity AUC by sampling deeper tissue layers. To the best of our knowledge, this is the first DRS study to investigate the potential of probing deeper tissue layers using larger SDD probes for CRC detection in the luminal wall. The data analysis showed that using a broader spectrum and longer near-infrared wavelengths can improve the diagnostic accuracy of CRC as well as probing deeper tissue layers.

Electrochemotherapy for colorectal cancer using endoscopic electroporation: a phase 1 clinical study.

Background and study aims Electrochemotherapy is an anticancer treatment that uses electric pulses to facilitate uptake of chemotherapeutic drugs in tumor cells and has proven to have a high local cytotoxic effect with minimal adverse events. Electrochemotherapy has mostly been used in treatment of cutaneous metastases but development of a new endoscopic electrode device has made treatment of colorectal tumors possible. This first-in-man multicenter phase I study investigated safety and efficacy of electrochemotherapy using endoscopic electroporation in patients with colorectal tumors. Patients and methods Seven patients with colorectal tumors who were deemed ineligible for or had declined standard treatment were included. They were treated with bleomycin either intratumorally or intravenously and the electric pulses were delivered through the endoscopic electrode device. Safety and efficacy were assessed clinically and by scans immediately after treatment and adverse events were reported. Response was evaluated up to 6 months after treatment by scans (magnetic resonance imaging or computed tomography) and endoscopic examinations. Results Seven patients aged 62 to 88 years with multiple comorbidities were included and had one or two treatments each. Post-treatment scans showed tumor responses in the treated areas and no damage to surrounding tissues. Only a few grade one adverse events were reported. Three patients had preoperative rectal bleeding, of which two reported cessation of bleeding and one reported decreased bleeding. Conclusion This first-in-man study shows that electrochemotherapy for colorectal tumors using the endoscopic electrode device can induce local tumor response and is safe also for fragile elderly patients with comorbidities.

Impaction of swallowed dentures in the sigmoid colon requiring sigmoid colectomy.

INTRODUCTION: Foreign body (FB) ingestion results in perforation in 1% of cases and is associated with significant morbidity and rarely mortality. Clinical presentation is variable and can present a diagnostic challenge. We report our experience and management of a patient with a delayed presentation of a sigmoid colon foreign body as a result of ingestion of a dental plate. PRESENTATION OF CASE: A 67 year old female attended the colorectal outpatient clinic following an incidental finding of a sigmoid mass on computed tomography (CT) abdomen. Further investigation identified a dental plate impacted in a thickened sigmoid colon. On further questioning the patient recalled losing her dentures three years previously. At surgery the dental plate had partially eroded through the sigmoid colon into the pelvic side wall. A sigmoid colectomy and hand sewn end-to-end colo-colic anastomosis was performed. DISCUSSION: Localised perforation following ingestion of a foreign body may result in significant morbidity. Extra luminal migration and local inflammatory response resulted in the formation of a walled off collection. Delayed complications of perforation include abscess and fistula formation. CONCLUSION: Clinicians need to exhibit a high index of suspicion when treating edentulous patients and alcohol and drug abusers who present with an acute abdomen or a sub-acute presentation with associated atypical imaging and endoscopic findings. The decision regarding intervention and management strategy in cases of perforation by foreign body depends on chronicity of the case, extent of localised or diffuse peritonitis, and size of the lesion or area of bowel involved.

Tumour-associated and non-tumour-associated microbiota: Addendum.

In a recent study1 we reported that tissue-associated microbial Co-abundance Groups (CAGs) were differentially associated with colorectal cancer (CRC). Two of the CAGs, which we named Pathogen CAG and Prevotella CAG, were correlated with a gene expression signature indicative of a TH17 response. A TH17 response has been associated with decreased survival in patients with CRC2, and members of the Pathogen CAG such as Fusobacterium nucleatum, Escherichia coli and Bacteroides fragilis have been repeatedly reported to be associated with CRC-development. Thus we hypothesized that the abundance of these CAGs may be associated with poor survival. In this Addendum we extend our analysis of the at-surgery microbiota to microbiota profiles obtained after surgery for CRC which we analyzed in the context of survival data for patients with CRC. Surprisingly we found that high tissue-associated abundance of the previously defined Prevotella- and Pathogen-CAGs at surgery was associated with longer survival. Furthermore, we detected an association of the Bacteroidetes CAG in pre-surgery faecal microbiota with stability of the microbiota after surgery.

The oral microbiota in colorectal cancer is distinctive and predictive.

BACKGROUND AND AIMS: Microbiota alterations are linked with colorectal cancer (CRC) and notably higher abundance of putative oral bacteria on colonic tumours. However, it is not known if colonic mucosa-associated taxa are indeed orally derived, if such cases are a distinct subset of patients or if the oral microbiome is generally suitable for screening for CRC. METHODS: We profiled the microbiota in oral swabs, colonic mucosae and stool from individuals with CRC (99 subjects), colorectal polyps (32) or controls (103). RESULTS: Several oral taxa were differentially abundant in CRC compared with controls, for example, Streptococcus and Prevotellas pp. A classification model of oral swab microbiota distinguished individuals with CRC or polyps from controls (sensitivity: 53% (CRC)/67% (polyps); specificity: 96%). Combining the data from faecal microbiota and oral swab microbiota increased the sensitivity of this model to 76% (CRC)/88% (polyps). We detected similar bacterial networks in colonic microbiota and oral microbiota datasets comprising putative oral biofilm forming bacteria. While these taxa were more abundant in CRC, core networks between pathogenic, CRC-associated oral bacteria such as Peptostreptococcus, Parvimonas and Fusobacterium were also detected in healthy controls. High abundance of Lachnospiraceae was negatively associated with the colonisation of colonic tissue with oral-like bacterial networks suggesting a protective role for certain microbiota types against CRC, possibly by conferring colonisation resistance to CRC-associated oral taxa and possibly mediated through habitual diet. CONCLUSION: The heterogeneity of CRC may relate to microbiota types that either predispose or provide resistance to the disease, and profiling the oral microbiome may offer an alternative screen for detecting CRC.

Tumour-associated and non-tumour-associated microbiota in colorectal cancer.

OBJECTIVE: A signature that unifies the colorectal cancer (CRC) microbiota across multiple studies has not been identified. In addition to methodological variance, heterogeneity may be caused by both microbial and host response differences, which was addressed in this study. DESIGN: We prospectively studied the colonic microbiota and the expression of specific host response genes using faecal and mucosal samples ('ON' and 'OFF' the tumour, proximal and distal) from 59 patients undergoing surgery for CRC, 21 individuals with polyps and 56 healthy controls. Microbiota composition was determined by 16S rRNA amplicon sequencing; expression of host genes involved in CRC progression and immune response was quantified by real-time quantitative PCR. RESULTS: The microbiota of patients with CRC differed from that of controls, but alterations were not restricted to the cancerous tissue. Differences between distal and proximal cancers were detected and faecal microbiota only partially reflected mucosal microbiota in CRC. Patients with CRC can be stratified based on higher level structures of mucosal-associated bacterial co-abundance groups (CAGs) that resemble the previously formulated concept of enterotypes. Of these, Bacteroidetes Cluster 1 and Firmicutes Cluster 1 were in decreased abundance in CRC mucosa, whereas Bacteroidetes Cluster 2, Firmicutes Cluster 2, Pathogen Cluster and Prevotella Cluster showed increased abundance in CRC mucosa. CRC-associated CAGs were differentially correlated with the expression of host immunoinflammatory response genes. CONCLUSIONS: CRC-associated microbiota profiles differ from those in healthy subjects and are linked with distinct mucosal gene-expression profiles. Compositional alterations in the microbiota are not restricted to cancerous tissue and differ between distal and proximal cancers.

An antitumorigenic role for the IL-33 receptor, ST2L, in colon cancer.

BACKGROUND: Despite the importance of inflammation in cancer, the role of the cytokine IL-33, and its receptor ST2, in colon cancer is unclear. The aim of this study was to investigate the role of IL-33, and its receptor isoforms (ST2 and ST2L), in colon cancer. METHODS: Serum levels of IL-33 and sST2 were determined with ELISA. ST2 and IL-33 expression was detected with quantitative real-time PCR (qRT-PCR), western blotting and immunohistochemistry. ST2 expression in CT26 cells was stably suppressed using ST2-specific shRNA. Cytokine and chemokine gene expression was detected with qRT-PCR. RESULTS: Human colon tumours showed lower expression of ST2L as compared with adjacent non-tumour tissue (P<0.01). Moreover, the higher the tumour grade, the lower the expression of ST2L (P=0.026). Colon cancer cells expressed ST2 and IL-33 in vitro. Functional analyses showed that stimulation of tumour cells with IL-33 induced the expression of chemokine (C-C motif) ligand 2 (CCL2). Knockdown of ST2 in murine colon cancer cells resulted in enhanced tumour growth (P<0.05) in BALB/c mice in vivo. This was associated with a decrease in macrophage infiltration, with IL-33-induced macrophage recruitment reduced by antagonising CCL2 in vitro. CONCLUSION: The IL-33/ST2 signalling axis may have a protective role in colon carcinogenesis.

Design, development and evaluation of an inflatable retractor for atraumatic retraction in laparoscopic colectomy.

Laparoscopic colectomy is the gold standard in the treatment of malignant tumours arising in the mucosa of the colon wall. The procedure is performed under general endotracheal anaesthesia and involves establishing a pneumoperitoneum with the patient in the Trendelenburg position. However this position can cause anaesthetic difficulties due to excess blood flow to the head and neck, increased pressure on the diaphragm and increased venous pressure. In the absence of steep head-down positioning, the bowels fall or "spill" into the operating field, obstructing the surgical space. The primary goal of this work is to design an atraumatic laparoscopic retractor to minimise the Trendelenburg position whilst effectively retracting the bowels from the operating field. This work details the design, evaluation and optimisation of a novel, hand held, inflatable, laparoscopic retractor, through physical experimentation, computer simulation, and pre-clinical animal investigation. The optimised design for the inflatable retractor performs in line with simulated expectations, and was successfully tested for safety and technical feasibility in vivo in a porcine model, where the bowels were effectively removed from the operating space whilst the model remained in the supine position. These initial results represent a promising approach for the mitigation of the Trendelenburg position, whilst effectively retracting the bowels during laparoscopic colectomy, using this atraumatic, inflatable retractor.