Commonalities and differences in the mutational signature and somatic driver mutation landscape across solid and hollow viscus organs

Advances in sequencing have revealed a highly variegated landscape of mutational signatures and somatic driver mutations in a range of normal tissues. Normal tissues accumulate mutations at varying rates ranging from 11 per cell per year in the liver, to 1879 per cell per year in the bladder. In addition, some normal tissues are also comprised of a large proportion of cells which possess driver mutations while appearing phenotypically normal, as in the oesophagus where a majority of cells harbour driver mutations. Individual tissue proliferation and mutation rate, unique mutagenic stimuli, and local tissue architecture contribute to this highly variegated landscape which confounds the functional characterization of driver mutations found in normal tissue. In particular, our understanding of the relationship between normal tissue somatic mutations and tumour initiation or future cancer risk remains poor. Here, we describe the mutational signatures and somatic driver mutations in solid and hollow viscus organs, highlighting unique characteristics in a tissue-specific manner, while simultaneously seeking to describe commonalities which can bring forward a basic unified theory on the role of these driver mutations in tumour initiation. We discuss novel findings which can be used to inform future research in this field.

Biallelic FBXW7 knockout induces AKAP8-mediated DNA damage in neighbouring wildtype cells

Colorectal cancer possesses marked intratumoral heterogeneity. While subclonal interactions between Vogelstein driver mutations have been extensively studied, less is known about competitive or cooperative effects between subclonal populations with other cancer driver mutations. FBXW7 is a cancer driver mutation which is present in close to 17% of colorectal cancer cells. In this study, we generated isogenic FBXW7 mutant cells using CRISPR-Cas9. We identified an upregulation of oxidative phosphorylation and DNA damage in FBXW7 mutant cells, which surprisingly proliferated at a decreased rate compared to wildtype cells. To determine subclonal interactions, wildtype and mutant FBXW7 cells were cocultured using a Transwell system. Wildtype cells cocultured with FBXW7 mutant cells similarly developed DNA damage which was not observed when wildtype cells were co-cultured with other wildtype cells, suggesting that FBXW7 mutant cells were inducing DNA damage in neighbouring wildtype cells. Using mass spectrometry, we identified AKAP8 as being secreted by FBXW7 mutant cells into the coculture media. Furthermore, overexpression of AKAP8 in wildtype cells recapitulated the DNA damage phenotype observed during coculture, while co-culture of wildtype cells with double mutant FBXW7^-/-/AKAP8^-/- cells abrogated the DNA damage phenotype. Here, we describe a hitherto unknown phenomenon of AKAP8-mediated DNA damage from FBXW7 mutant to neighbouring wildtype cells. Our findings demonstrate the importance of elucidating the local effect of cancer driver mutations between subclonal populations.

Domain-specific p53 mutants activate EGFR by distinct mechanisms exposing tissue-independent therapeutic vulnerabilities

Mis-sense mutations affecting TP53 promote carcinogenesis both by inactivating tumor suppression, and by conferring pro-carcinogenic activities. We report here that p53 DNA-binding domain (DBD) and transactivation domain (TAD) mis-sense mutants unexpectedly activate pro-carcinogenic epidermal growth factor receptor (EGFR) signaling via distinct, previously unrecognized molecular mechanisms. DBD- and TAD-specific TP53 mutants exhibited different cellular localization and induced distinct gene expression profiles. In multiple tissues, EGFR is stabilized by TAD and DBD mutants in the cytosolic and nuclear compartments respectively. TAD mutants promote EGFR-mediated signaling by enhancing EGFR interaction with AKT via DDX31 in the cytosol. Conversely, DBD mutants maintain EGFR activity in the nucleus, by blocking EGFR interaction with the phosphatase SHP1, triggering c-Myc and Cyclin D1 upregulation. Our findings suggest that p53 mutants carrying gain-of-function, mis-sense mutations affecting two different domains form new protein complexes that promote carcinogenesis by enhancing EGFR signaling via distinctive mechanisms, exposing clinically relevant therapeutic vulnerabilities.

Generation and immunofluorescent validation of gene knockouts in adult human colonic organoids using multi-guide RNA CRISPR-Cas9

While readily achieved in cell lines, the application of CRISPR-Cas9 gene editing in human-derived organoids suffers from limited efficacy and complex protocols. Here, we describe a multi-guide RNA CRISPR-Cas9 gene-editing protocol which efficiently achieves complete gene knockout in adult human colonic organoids. This protocol also describes crucial steps including how to harvest patient tissue to maximize gene-editing efficacy and a technique to validate gene knockout following editing with immunofluorescent staining of the organoids against the target protein.

Predictors of Clinical Outcomes in Acute Appendicitis: A Retrospective Study

INTRODUCTION

Acute appendicitis is one of the most common causes of intra-abdominal emergency surgery worldwide. This study was conducted to contribute to global databases by presenting data from our institution, which consist of multi-racial population. We aimed to evaluate the presentation, diagnosis, and management of acute appendicitis and post-operative outcome in our institution and evaluate the risks factors associated with severe complications and prolonged length of stay (LOS).

MATERIALS AND METHODS

We performed a retrospective analysis using multivariate regression analysis of all patients who underwent appendectomy (2009-2014) in our institution. The primary outcomes included demographics, presentation, and perioperative management, and the secondary outcomes included risk factors associated with prolonged LOS.

RESULTS

Of the 1185 patients, the mean age was 36.4 years, and 940 (79.3%) were male. Majority (98.1%) of patients were ASA (American Society of Anaesthesiologists) 1 or 2. Most of them (83.9%) were from the four racial subgroups (Chinese, Malay, Bangladeshi, and Indian). There was no racial variation in the diagnosis and presentation of disease. The mean duration of symptoms was 1.8 days. The history was commonly a localised or migratory abdominal pain associated with anorexia, nausea, vomiting, and fever. The commonest physical findings were right-sided abdominal tenderness associated with rebound and guarding. About 42.9% of the patients underwent pre-operative CT scan to establish the diagnosis of appendicitis prior to surgery, whilst 57.1% underwent surgery on clinical diagnosis and blood investigation (NWR and CRP). An open appendectomy was performed in 13.2% of the patients. The conversion rate of laparoscopic appendectomy was 4.9% (n = 50). The mean length of hospital stay was 3.6 days. On multivariate Cox regression, patients of Burmese and Thai descent were independently associated with a prolonged LOS. The postoperative morbidity was 5.5%. The 30-day readmission rate was 2.4%. There was no mortality in our study.

DISCUSSION

Our study showed that pre-operative diagnosis of acute appendicitis can be made accurately by classical clinical presentation or by imaging. Independent risk factors associated with increased LOS included increased age, male gender, prolonged duration of symptoms pre-admission, fever, generalised tenderness, and prolonged operative time. The effect of race on LOS has been observed in the literature for other surgical procedures. The prolonged LOS found in Burmese and Thai patients contribute to the possibility of intrinsic racial differences in the post-surgery recovery. However, the numbers are small and therefore prone to type I error. Compared to the open approach, the use of laparoscopic appendectomy was associated with shorter LOS. This has similar outcomes to those reported in the literature.

CONCLUSION

The identification of risks factors could help surgical team to predict the clinical outcomes and develop risk reduction strategy in post-operative care of these patients.

Perioperative and oncologic outcomes in young and octogenarian patients with colorectal cancer: a comparison at the extremes

INTRODUCTION

In colorectal cancer (CRC), surgical outcomes in the young (< 50) and octogenarian populations are believed to be poor due to an aggressive phenotype in the former, and increased frailty in the latter. Given that age-related effects are inversely related between groups, we compared short- and long-term outcomes of young and octogenarian patients with CRC to determine the dominance of one age-related factor over another.

METHODS

A prospectively collected database from 2015 to 2020 of all CRC was analyzed. Cases were divided into metastatic and non-metastatic groups.

RESULTS

Among non-metastatic cases, there were 34 young and 113 octogenarian patients. Mean CEA was higher among octogenarians (11.2 vs 32.8 units/ml; p = 0.041). Octogenarians suffered from more comorbidities than younger counterparts, with increased rates of postoperative UTI (3.3% vs 10.3%; p = 0.246) and pneumonia (3.1% vs 8.8%; p = 0.331). There was no increased rate of reintervention or Clavien-Dindo scores. We noticed a statistically significant higher proportion of extramural vascular invasion (EMVI) (8.8% vs 32.3%; p = 0.003) among the young. When excluding octogenarians who had declined surgery, Kaplan-Meier analysis showed no difference in disease-free (p = 0.290) or overall survival (p = 0.111). Among metastatic cases, there were 21 young and 19 octogenarian patients. Young patients were treated more aggressively with chemotherapy (55.6% vs 12.5%; p = 0.040). There was however no difference in overall survival between groups (p = 0.610).

CONCLUSIONS

Octogenarians may have more comorbidities, but can achieve similar surgical outcomes with younger patients. There is no reason to suspect a more aggressive phenotype in younger patients.

Tumour heterogeneity and evolutionary dynamics in colorectal cancer

Colorectal cancer (CRC) has a global burden of disease. Our current understanding of CRC has progressed from initial discoveries which focused on the stepwise accumulation of key driver mutations, as encapsulated in the Vogelstein model, to one in which marked heterogeneity leads to a complex interplay between clonal populations. Current evidence suggests that an initial explosion, or “Big Bang”, of genetic diversity is followed by a period of neutral dynamics. A thorough understanding of this interplay between clonal populations during neutral evolution gives insights into the roles in which driver genes may participate in the progress from normal colonic epithelium to adenoma and carcinoma. Recent advances have focused not only on genetics, transcriptomics, and proteomics but have also investigated the ecological and evolutionary processes which transform normal cells into cancer. This review first describes the role which driver mutations play in the Vogelstein model and subsequently demonstrates the evidence which supports a more complex model. This article also aims to underscore the significance of tumour heterogeneity and diverse clonal populations in cancer progression.

Chemotherapy and adverse cardiovascular events in colorectal cancer patients undergoing surgical resection

Abstract

Background

Colorectal cancer patients undergoing surgical resection are at increased short-term risk of post-operative adverse events. However, specific predictors for long-term major adverse cardiac and cerebrovascular events (MACCE) are unclear. We hypothesised that patients who receive chemotherapy are at higher risk of MACCE than those who did not.

Methods

In this retrospective study, 412 patients who underwent surgical resection for newly diagnosed colorectal cancer from January 2013 to April 2015 were grouped according to chemotherapy status. MACCE was defined as a composite of cardiovascular death, myocardial infarction, stroke, unplanned revascularisation, hospitalisation for heart failure or angina. Predictors of MACCE were identified using competing risks regression, with non-cardiovascular death a competing risk.

Results

There were 200 patients in the chemotherapy group and 212 patients in the non-chemotherapy group. The overall prevalence of prior cardiovascular disease was 20.9%. Over a median follow-up duration of 5.1 years from diagnosis, the incidence of MACCE was 13.3%. Diabetes mellitus and prior cardiovascular disease were associated with an increased risk of MACCE (subdistribution hazard ratio, 2.56; 95% CI, 1.48-4.42) and 2.38 (95% CI, 1.36-4.18) respectively. The chemotherapy group was associated with a lower risk of MACCE (subdistribution hazard ratio, 0.37; 95% CI, 0.19-0.75) compared to the non-chemotherapy group.

Conclusions

Amongst colorectal cancer patients undergoing surgical resection, there was a high incidence of MACCE. Diabetes mellitus and prior cardiovascular disease were associated with an increased risk of MACCE. Chemotherapy was associated with a lower risk of MACCE, but further research is required to clarify this association.

Early surgery after bridge-to-surgery stenting for malignant bowel obstruction is associated with better oncological outcomes

BACKGROUND

Placement of self-expanding metal stents has been increasingly adopted as a bridge to surgery in patients presenting with obstructed left-sided colorectal cancers. The optimal bridging time has yet to be widely established, hence this retrospective study aims to determine the optimal bridging time to elective surgery post endoluminal stenting.

PATIENTS AND METHODS

All patients who underwent colorectal stenting for large bowel obstruction in a single, tertiary hospital in Singapore between January 2003 and December 2017 were retrospectively identified. Patients' baseline demographics, tumour characteristics, stent-related complications, intra-operative details, post-operative complications and oncological outcomes were analysed.

RESULTS

Of the 53 patients who successfully underwent colonic stenting for malignant left sided obstruction, 33.96% of patients underwent surgery within two weeks of stent placement while 66.04% of patients underwent surgery after 2 weeks of stent placement. Univariate analysis between both groups did not demonstrate significant differences in postoperative complications and stoma formation. Significant differences were observed between both groups for stent complications (38.89% vs 8.57%, p = 0.022), on-table decompression (38.89% vs 2.86%, p = 0.001) and systemic recurrence (11.11% vs 40.00%, p = 0.030). Increased bridging interval to surgery (OR 13.16, CI 1.37-126.96, p = 0.026) was a significant risk factor for systemic recurrence on multivariate analysis.

CONCLUSIONS

Patients undergoing definitive surgery within 2 weeks of colonic stenting may have better oncological outcomes without compromising on postoperative outcomes. Further prospective studies are required to compare outcomes between emergency surgery and different bridging intervals.

Continuous wound infusion with ropivacaine alone provides adequate analgesia following laparotomy

BACKGROUND

Although continuous wound infusion (CWI) with local anaesthetic has been used as an adjunct for pain relief following laparotomy, its use as the main modality has not been studied. This approach negates side effects related to intravenous opioid administration, therefore promoting enhanced recovery from surgery. We conducted this study to investigate the feasibility and efficacy of CWI following laparotomy.

METHODS

Consecutive patients who underwent laparotomy from June 2016 to December 2019 were analysed. All patients were given CWI with only oral supplementation. Pain was assessed based on the numeric rating scale (NRS).

RESULTS

One hundred and three patients were analysed. Mean age was 61.1 (standard deviation 16.7). 47.6% of patients were operated for intestinal obstruction. Large bowel resection was the most common operation performed (49.5%). 69.9% of patients underwent emergency surgery, whilst 51.5% of patients had surgery for cancer. On postoperative day 0, NRS was 3.2 (standard deviation (sd) 2.6) which decreased to 1.5 (sd 1.9) on day 3, and 1.1 (sd 1.8) on day 5. Mean time to flatus was 2.3 (sd 1.4) days, whilst mean time to first bowel movement was 3.1 (sd 1.7) days. Patients were able to commence ambulation by 2.5 (sd 1.8) days. Patients could tolerate a normal diet on day 3.9 (sd 3.3), and IV drip was removed on day 3.5 (sd 3.0). Mean length of stay was 9.1 (sd 6.9) days. Only two patients suffered from respiratory depression (1.9%) whilst five patients suffered from hypotension (4.9%). No patients had pruritus. 23.3% of patients had nausea or vomiting. Only one patient had a catheter-related complication which was easily addressed.

CONCLUSION

CWI provides adequate pain relief as the principle modality of analgesia after surgery, without opioid side effects.

Lymphocyte-White Cell Ratio Is a Novel Marker of Morbidity Following Colorectal Cancer Surgery

BACKGROUND

A preoperative marker for morbidity in patients with colorectal cancer would help to risk stratify patients and allow for timely intervention to avert poor outcomes. We conducted this study to evaluate preoperative lymphocyte-white blood cell ratio (LWR) as a marker of postoperative morbidity.

METHODS

A prospective cohort of patients who underwent elective surgery for colorectal cancer was reviewed. Three morbidity-related outcomes were described-overall morbidity, multiple morbidities, and severe morbidity, defined as Clavien-Dindo Class ≥3. Univariable and multivariable analyses of presurgical predictors of these three outcomes were performed. Preoperative variables included hemoglobin levels, neoadjuvant therapy, albumin levels, white blood cell count, lymphocyte count, LWR, neutrophil-lymphocyte ratio, and prognostic nutritional index.

RESULTS

Of 177 patients, 31.6% (56/177) suffered at least one morbidity, 15.3% (27/177) had multiple morbidities, 7.9% (14/177) suffered severe morbidity. On multivariate analysis, only LWR <0.180 (odds ratio [OR] 2.53, 95% confidence interval [CI] 1.15-5.55) and neoadjuvant therapy (OR 2.49, 95% CI 1.16-5.24) were associated with overall morbidity. For multiple morbidities and severe morbidity, only LWR <0.180 was significantly associated on multivariate analysis with an OR of 2.92 (95% CI 1.19-7.13) and 4.62 (95% CI 1.45-14.73), respectively.

CONCLUSIONS

LWR is a preoperative marker which can be conveniently applied using standard preoperative blood tests. LWR is an independent risk factor for overall morbidity, multiple morbidities, as well as severe morbidity when used with a cut-off of LWR<1.80.

A simple prediction score for prolonged length of stay following elective colorectal cancer surgery

BACKGROUND

Current enhanced recovery after surgery (ERAS) protocols are designed for all patients without tailored programmes for at-risk groups. A risk score to determine elective colorectal cancer patients at risk for prolonged length of stay (LOS) would help to identify this group for preoperative intervention.

METHODS

Multivariate analysis of demographic and preoperative variables was performed to identify independent risk factors for prolonged LOS, defined as 7 days or more. A stepwise variable selection approach using logistic regression was then used to build a risk prediction model.

RESULTS

Among 172 patients in our population, 41.9% of patients had prolonged LOS. Five variables were included in our risk prediction model. These were age ≥ 65 years (OR 13.9 5.09-38.0; p < 0.0001), neoadjuvant therapy (OR 7.60 2.51-23.0; p < 0.0001), open approach (OR 3.96 1.68-15.9); p = 0.008), history of smoking (OR 5.18 1.68-15.9; p = 0.004) and white blood cell (WBC) count (OR 0.83/unit 0.69-0.99; p = 0.040). These variables were combined to produce a score, for which the area under the receiving operator curve was 0.82 (95% CI 0.76-0.88), and Hosmer-Lemeshow test showed a χ² statistic of 9.14 and p = 0.519. Using 0.9 as a cut-off, the score has sensitivity of 81.9% and specificity of 65.0%.

CONCLUSION

A simple, clinical score can be used to predict for prolonged LOS based on preoperative variables, allowing for intervention before surgery. Age, neoadjuvant therapy, smoking status, open approach and WBC count are independent risk factors for prolonged length of stay following elective colorectal cancer surgery. A risk score comprising the above independent variables was developed with area under the receiving operator curve of 0.82 (95% CI 0.76-0.88), and a Hosmer-Lemeshow test showing a χ2 statistic of 9.14 and p = 0.519.

Stenting versus surgery in obstructed malignant colorectal cancer-a review of short and long-term results

Obstructed colorectal cancers (CRCs) continue to be challenging to manage. Apart from surgical resection, the use of self-expanding metallic stents (SEMS) has become increasingly popular. SEMS could potentially allow for the conversion of an emergency operation into a semi-elective procedure, allow for the optimization of the patient's physiology, avoid the requirement for a stoma, as well as allow for a minimally-invasive approach to be adopted. This review article therefore highlights the evidence available in the literature pertaining to the use of SEMS in obstructed CRCs.

Journey for patients following ileostomy creation is not straightforward

BACKGROUND

An ileostomy is usually created to avert systemic sepsis in a patient with a tenuous anastomosis. However, what is often not reported are the numerous issues facing these patients subsequently, ranging from readmissions, non-reversal of the stoma, and complications from the closure. This study was performed to identify these issues among patients following creation of an ileostomy.

METHODS

We conducted a retrospective analysis of consecutive patients who had an ileostomy created from January 2011 to December 2016 at two institutions. Statistical analysis was performed to identify risk factors associated with readmissions and ileostomy non-reversal.

RESULTS

In total, 193 patients had an ileostomy created during the study period. Twenty-six (13.5%) patients developed stoma-related complications requiring readmission. The most common cause of readmission (9.3%) was due to dehydration and acute kidney injury secondary to high stoma output. One hundred thirty (67.4%) patients had their ileostomy reversed. On multivariate analysis, only stomas created during an ultra-low anterior resection were associated with reversal (OR 2.88 [95% CI, 1.24-6.68]; p = 0.014). Among the patients who underwent ileostomy reversal, seven (3.6%) patients developed complications from their ileostomy reversal. Four patients (2.1%) suffered from an anastomotic leak which required repeat surgical intervention with one mortality from the ensuing sepsis.

CONCLUSION

Almost half of the patients who had an Ileostomy had an undesirable outcome, including readmissions, non-reversal, and post-operative complications following closure. Patients need to be properly counselled about the risks involved prior to the index operation.

Diagnostic and management strategies for lateral pelvic lymph nodes in low rectal cancer-a review of the evidence

Patients with low rectal cancer who have enlarged lateral pelvic lymph nodes are known to have a worse prognosis. There is however uncertainty over what constitutes a lateral pelvic lymph node of clinical significance. As the main modality for the detection of such lymph nodes is magnetic resonance imaging (MRI), characteristics of these lateral lymph nodes identified may have prognostic value and assist with guiding treatment. Options to manage such lateral lymph nodes includes neoadjuvant chemoradiotherapy as well as lateral lymph node dissection. Surgery is extensive and may lead to significant morbidity to the patient. This review article evaluates diagnostic and management strategies in patients with lateral pelvic lymph nodes in low rectal cancer.

Nasal Cavity Metastasis From Colorectal Cancer Represents End-Stage Disease and Should Be Palliated

Nasal metastases from colorectal cancer is rare. The presentation of nasal metastases is often very similar to primary nasal sinus adenocarcinoma. A high index of suspicion is required, especially in patients who have had a previous history of colorectal carcinoma. Histology is ultimately required for diagnosis. We describe 2 cases of nasal metastases from colorectal carcinoma, and discuss the presentation, diagnosis and management of the case. Such metastatic disease ultimately represents end-stage malignancy, and patients should be palliated.

Successful use of tissue expander and pelvic sling to exclude small bowel for high-dose pelvic irradiation

OBJECTIVE

Our study seeks to describe our surgical technique of the use of a tissue expander and a pelvic sling in order to perform high-dose pelvic irradiation without incurring radiation toxicity to the small bowel. High-dose radiation therapy for pelvic tumours comes at a risk of radiation toxicity to the small bowel. Our study discusses our novel surgical technique of compartmentalising the abdomen and the pelvis through the use of a tissue expander and pelvic sling to avoid small bowel radiation toxicity.

METHODS

We present a patient with an unresectable sacral chordoma. We describe our surgical technique incorporating both a tissue expander and an absorbable pelvic mesh sling to successfully compartmentalise the abdomen from the pelvis.

RESULTS

The patient underwent an uneventful surgical procedure to place the tissue expander within the pelvis and deploy the pelvic mesh sling. Following surgery, a separation of at least 8 cm was achieved between bowel loops and the tumour. A dose of 70 Gy delivered over 35 fractions using intensity modulated radiotherapy (IMRT) was administered to the sacral chordoma, whilst managing to constrain the maximum bowel dose to 35.7 Gy. Surgery to remove the tissue expander was uneventful. The patient has not suffered any small bowel irradiation toxicity.

CONCLUSIONS

Our technique to exclude small bowel from the pelvis is effective and safe. This technique not only can be applied in the setting of unresectable sacral chordomas but also may be applicable to other pelvic cancers which require radiation therapy.

Anal Adenocarcinoma Can Masquerade as Chronic Anal Fistula in Asians

Purpose

Perianal adenocarcinoma arising from a chronic anorectal fistula is a rare condition for which the natural history and optimal management are not well established. For that reason, we conducted a retrospective analysis of 5 consecutive patients with a perianal adenocarcinoma arising from a chronic anorectal fistula managed at our institution from January 2014 to December 2015.

Methods

The patients were identified from a prospectively collected colorectal cancer database that included all patients managed for colorectal cancer at our institution.

Results

The median age at diagnosis was 64 years (range, 55–72 years). Magnetic resonance imaging (MRI) was the initial investigation for all patients and showed a hyperintense T2-weighted image. One patient underwent an abdominoperineal resection following neoadjuvant chemoradiotherapy and remained disease free during the 12-month follow-up. Three patients received neoadjuvant therapy with intent for surgery, but did not undergo surgery due to either worsening health or metastatic spread. One patient declined intervention. The median overall survival was 10.5 months (range, 2–19 months).

Conclusion

A high index of suspicion is required to make a clinical diagnosis of an anal adenocarcinoma arising from a chronic fistula. Histologic diagnosis must be achieved to confirm the diagnosis. Multimodal therapy with neoadjuvant chemoradiotherapy followed by abdominoperineal resection is the treatment of choice.

Endoscopic stenting should be advocated in patients with stage IV colorectal cancer presenting with acute obstruction

Background

It remains contentious whether endoscopic stenting or upfront surgery is more optimal in patients with metastatic colorectal cancers presenting with large bowel obstruction.

Methods

A retrospective review of all patients with metastatic colorectal cancer who underwent either endoscopic stenting or emergency surgery for acute large bowel obstruction was performed.

Results

Between January 2007 and June 2014, 66 patients, median age, 64 (range, 25-96) years, presented with acute large bowel obstruction from metastatic colorectal cancer. Forty (60.6%) patients underwent endoscopic stenting whilst the rest received immediate upfront surgical intervention. Of the 40 patients, 29 (72.5%) were successfully stented. The remaining 11 (27.5%) patients who failed endoscopic stenting required immediate emergency surgery to relieve the obstruction. Patients who failed endoscopic stenting had worse complications than those patients who had their stents successfully inserted [odds ratio (OR), 23.3; 95% confidence interval (CI), 2.29-250.00, P=0.004]. Patients who underwent emergency surgery had a longer median length of stay than patients who had successful endoscopic stenting (P=0.003). The patients that underwent successful stenting had earlier commencement of chemotherapy compared to those who had upfront surgery (P=0.02). There was no difference in stoma creation rates between patients who had emergency surgery versus those who were successfully stented.

Conclusions

Stenting is a safe option in patients with stage IV colorectal cancer presenting with acute large bowel obstruction. Earlier commencement of chemotherapy occurs in patients who were successfully stented. Patients who failed stenting have equivalent outcomes to those who undergone upfront emergency surgery.

Subclassification of Bethesda Atypical and Follicular Neoplasm Categories According to Nuclear and Architectural Atypia Improves Discrimination of Thyroid Malignancy Risk

BACKGROUND

Although The Bethesda System for Reporting Thyroid Cytopathology has provided clinicians with a standardized classification scheme for the diagnosis of thyroid fine-needle aspiration cytology (FNAC) specimens, the indeterminate categories of Bethesda III (B3)-atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS)-and Bethesda IV (B4)-follicular neoplasm/suspicious for follicular neoplasm (FN/SFN)-continue to pose challenges with regards to ideal diagnostic and therapeutic management. Having previously demonstrated the presence of nuclear atypia as a high-risk subgroup in B3, the objective of this study was to evaluate the malignancy rates in the B4 subgroup with nuclear atypia.

METHODS

A retrospective review of all thyroid FNACs diagnosed as B4 (FN/SFN) between 2008 and 2015 was conducted at a tertiary referral center in Singapore. Data on patient demographics, sonographic features, and final histological diagnosis were collected. This was compared to data from a previous analysis on all nodules diagnosed as B3 (AUS/FLUS) over a similar period.

RESULTS

A total of 137/309 (44.3%) and 88/111 (79.3%) FNACs diagnosed as B3 and B4, respectively, underwent surgical excision yielding final histopathological diagnoses. The malignancy rate of B4 was 31/88 (35.2%) compared to B3, which was 37/137 (27.0%). Subclassification based on the presence of architectural versus nuclear atypia showed significantly higher malignancy rates in B4 nodules with nuclear atypia (21.8% vs. 57.6%; p < 0.01). These findings corroborate previous results within the B3 category (malignancy rate of 14.7% vs. 36.8%; p < 0.01). The only sonographic features predictive of malignancy were the presence of macrocalcifications in B4 compared to irregularity of margins in B3.

CONCLUSION

The presence of nuclear atypia identifies subgroups with significant differential malignancy risks within both the B3 and B4 categories. This supports the notion that subclassification is a useful risk stratification tool that can guide diagnostic and therapeutic management of indeterminate thyroid nodules with heterogenous risk profiles.

Lower lymph node yield following neoadjuvant therapy for rectal cancer has no clinical significance

Background

Obtaining 12 lymph nodes following resection for rectal cancer is an important prognostic marker. However, patients who have received neoadjuvant therapy are known to have a lower lymph node yield. We conducted this study to determine the clinical significance of evaluating <12 versus ≥12 lymph nodes in individuals who underwent surgery following neoadjuvant therapy for rectal cancer.

Methods

A retrospective analysis of all patients who received neoadjuvant therapy for locally advanced rectal cancer between January 2008 and December 2014 followed by proctectomy was conducted.

Results

In total, 217 patients were treated for rectal cancer. Mean follow-up was 23.4 (interquartile range, 9-40.5) months. Sixty-three (29.0%) patients received neoadjuvant therapy. There was a statistically significant difference in the number of patients with <12 lymph node yield between those who received neoadjuvant therapy and those who did not (27.0% vs. 9.1%, P=0.001). Amongst the 63 patients who received neoadjuvant therapy, lymph node yield of ≥12 was not associated with a statistically significant difference in time to recurrence [hazard ratio (HR) 0.17; 95% confidence interval (CI), 0.01-2.01, P=0.160] or time to death (HR 1.07; 0.15-7.90, P=0.946). Kaplan-Meier curves also did not show any significant difference between those with <12 lymph nodes and those with ≥12 lymph nodes in terms of recurrence and death (P=0.203 and P=0.762 respectively).

Conclusions

Although neoadjuvant therapy reduces the lymph node yield during surgery for locally advanced rectal cancer, this has no significance on the overall survival of the patient.

T4N0 colon cancers should be treated like T3N1 disease

Background

Patients with positive lymph nodal involvement in colon cancer have always been deemed to fare worse than those without. However, questions have been increasingly raised on the true prognosis of T4N0 disease. We conducted this study to investigate how T4N0 disease would compare with T3N1 disease.

Methods

All patients with colon cancer treated from 2008 to 2014 was collected. Preoperative, intraoperative and histological information was compared between patients with T4N0 and T3N1 disease. Variables which significantly differed were included in multivariate analysis for recurrence and survival. Kaplan-Meier curves and cox regression analysis for time to recurrence and survival were evaluated.

Results

Seventy-eight patients had T4N0 colon cancer, while 160 had T3N1 disease. Vascular invasion, lymphatic invasion, total lymph node yield, and the administration of adjuvant chemotherapy were identified as variables for evaluation. Over a median follow-up of 41.4 (range, 21.6-65.0) months for T4N0 patients and 42.4 (range, 21.1-63.8) months for T3N1 patients, there was no statistically significant difference in the association of stage of cancer with survival [overall survival (OS): 0.97 (95% CI, 0.38-2.45), P=0.94]. Kaplan-Meier curves also showed no difference in time to death (P=0.867). There was no statistically significant difference in the time to death [hazard ratio (HR): 0.56 (95% CI, 0.20-1.55), P=0.26].

Conclusions

T4N0 colon cancers have similar outcomes to T3N1 disease and should be considered as stage III disease in future classification. Patients diagnosed with T4N0 disease should receive similar treatment as those with T3N1 disease and counselled accordingly.

Asian patients with Hinchey Ia acute diverticulitis: a condition for the ambulatory setting?

BACKGROUND

Diverticulitis in Asians is a different disease entity from Western counterparts. Few Asian studies have evaluated the management of acute Hinchey Ia diverticulitis with consideration for outpatient management. The purpose of this study was to evaluate the outcomes of Asian patients with Hinchey Ia acute diverticulitis.

METHODS

A retrospective review of all patients who were treated for Hinchey Ia acute colonic diverticulitis between 2012 and 2014 was performed. All patients were diagnosed on computed tomography (CT).

RESULTS

There were 129 patients with Hinchey Ia acute diverticulitis. Fifty-five (42.6%) patients were male, and the median age was 54 years (range, 30-86). Eighty-seven (67.4%) patients had right-sided diverticulitis. Most patients were treated empirically with intravenous ceftriaxone and metronidazole (89.1%). They were then discharged with oral antibiotics. Only 6.1% of patients had a positive blood culture. The median length of stay in the hospital was 4 (range, 3-4) days. Only three (2.3%) patients were readmitted for acute diverticulitis within 30 days. They were managed with antibiotics and discharged well. The repeated CT scans reconfirmed Hinchey Ia diverticulitis. No patients required emergency surgery, and there were no 30-day mortalities.

CONCLUSION

Asian patients with Hinchey Ia diverticulitis recovered well with conservative management and could be amenable to outpatient therapy. Future prospective studies should be performed amongst Asians to evaluate managing this condition in an ambulatory setting.

Accredited residents perform colonoscopy to the same high standards as consultants

BACKGROUND

Endoscopy remains a critical component of General Surgery and Gastroenterology training. Whilst residents need to gain experience, the quality of endoscopy which patients receive cannot be compromised. We conducted this study to compare quality indicators between consultants and residents with regards to colonoscopy.

METHODS

A review of colonoscopies from a prospectively collected database was performed from September 2011 to February 2016. Quality indicators such as caecum intubation rate, adenoma detection rate, adherence to a 6-min withdrawal rule, mean number of polyps detected per colonoscope, and complications were collected and compared between the two groups.

RESULTS

In total, out of 25,749 colonoscopies that were performed, 14,168 (55.0%) were performed by Consultants. Consultants achieved a better caecum intubation rate compared with residents (96.0% vs 94.9%, p < 0.001), and were more compliant to the 6-min withdrawal rule (74.7% vs 68.6%, p < 0.001). There were, however, no statistically significant differences in the adenoma detection rate (33.5% vs 34.5%, p = 0.098). Bleeding was a rare complication that was encountered more frequently in colonoscopies performed by consultants than for residents (0.002% vs 0.00008%, p < 0.001). There were only three (%) perforations in the entire series, and all were from colonoscopies performed by Consultants.

CONCLUSION

Given the proper training, residents are able to perform colonoscopy with the same level of competence as consultants. Whilst colonoscopic related complications are often tied to the difficulty of the procedures, the adherence to the 6-min withdrawal rule must be reinforced and continually educated to both residents and consultants.

Getting the first degree relatives to screen for colorectal cancer is harder than it seems-patients' and their first degree relatives' perspectives

INTRODUCTION

First degree relatives (FDR) of colorectal cancer (CRC) patients are at increased risk of CRC compared to the general population. However, screening colonoscopy rates amongst the FDRs remain dismal. The aim of the study was to explore the various issues amongst the patients and their FDR precluding their adoption of screening colonoscopy.

METHODS

A qualitative study of CRC patients and their FDRs was performed. Semi-structured interviews were conducted with participants using open-ended questions until data saturation was achieved. These qualitative data were then thematically analysed.

RESULTS

Fifty CRC patients and thirty-one FDRs were recruited between June 2015 and December 2015. For the patients, three main themes emerged, which include (i) poor understanding of the CRC screening guidelines for their FDRs, (ii) recommendations are lacking amongst medical professionals and (iii) numerous barriers are hindering patients from being advocates for screening colonoscopy for their FDRs. For the FDRs, three main themes emerged. These include (i) poor understanding of the exact CRC screening guidelines amongst the FDRs, (ii) the lack of health promotion efforts amongst medical professionals and (iii) barriers to the uptake of screening colonoscopy such as fear of colonoscopy, high cost of the procedure, its associated inconvenience and perceived invulnerability of the individual.

CONCLUSIONS

Patients and FDRs are not aware of the increased risks of developing CRC amongst the family members. Guidelines regarding screening are also not clearly understood. The numerous barriers that are present amongst the CRC patients and their FDRs can be addressed.

Laparoscopic surgery should be considered in T4 colon cancer

INTRODUCTION

Laparoscopy in T4 colon cancers is not widely advocated due to concerns regarding safety and oncologic efficacy. We conducted this study to compare the short- and long-term oncological outcomes between laparoscopic and open approaches in T4 colon cancers.

METHODS

A retrospective analysis of all patients who underwent surgery for T4 colon cancer from 2008 to 2014 was performed. Margin positive rate, lymph node yield, local or distant recurrence and overall survival were analysed.

RESULTS

A total of 59 patients received open surgery, whilst 93 underwent laparoscopic surgery, with a conversion rate of 8.6%. There was no difference in the various measured outcomes between the laparoscopic and open groups. The relative risks of positive margins and inadequate lymph node yield for staging were 0.95 (0.74-1.23, p = 0.692) and 1.01 (0.97-1.05, p = 0.710), respectively, for the laparoscopic group when compared to the open approach. Regarding long-term outcomes, the relative risk of local recurrence in the laparoscopic group was 0.99 (0.96-1.02, p = 0.477), whilst there were also no increased risks of developing distal recurrences at the liver (RR 1.19, 0.51-2.82, p = 0.684), lungs (RR 1.20, 0.50-2.87, p = 0.678) and peritoneum (RR 1.22, 0.51-2.95, p = 0.653) in the laparoscopic group. There was also no difference in the overall survival (RR 0.70, 0.42-1.16, p = 0.168). Patients were followed up for a median of 73.3 months (range 34.8-144.7).

CONCLUSION

Laparoscopic surgery does not compromise oncological outcomes in T4 colon cancers compared to the open approach. Because of its proven associated benefits, laparoscopy should be considered in selected T4 colon cancers.

Anal adenocarcinoma presenting as a non-healing ischiorectal wound

We describe the diagnosis and management of a patient with a progressively enlarging, non-healing ischiorectal wound. This patient was further evaluated with radiological investigations which showed the presence of a large left ischiorectal fossa mass. Histology confirmed this mass as an anal adenocarcinoma. Anal Adenocarcinoma is a rare condition that can arise from chronic inflammatory states. Treatment requires an abdomino-perineal resection with neoadjuvant therapy, and the goal of surgery is to achieve clear resection margins.

Is gastroscopy for fecal immunochemical test positive patients worthwhile?

BACKGROUND

The use of fecal immunochemical test (FIT) in the screening for colorectal cancer is long established. However, more than 50 % of patients with positive FITs have a negative colonoscopy. The role of a subsequent oesophago-gastro-duodenoscopy (OGD) is debatable. The aim of this study is to evaluate the yield of OGD in patients with positive FITs.

METHODOLOGY

A retrospective review of patients who underwent colonoscopy for a positive FIT between Jan. 2008 and Dec. 2012 was identified from a prospectively collected endoscopy database at the National University Hospital, Singapore. Patients who underwent concurrent or subsequent OGDs for positive FIT formed the study group. We considered any new cancer or significant upper gastrointestinal pathology such as peptic ulcer disease or gastritis requiring treatment as a positive examination.

RESULTS

A total of 202 patients underwent both a colonoscopy and an OGD for a positive FIT and formed the study group. One hundred and six (52.5 %) of them had a positive examination with gastritis and duodenitis representing the most common UGI pathology in 89 (44.1 %) patients. Twenty-nine (14.4 %) patients tested positive for helicobacter pylori infection and another 16 (7.9 %) patients had peptic ulcer disease. There were no UGI cancers detected. One patient had an esophageal leiomyoma that was treated conservatively.

CONCLUSION

Routine gastroscopy for FIT positivity has a high diagnostic yield for benign upper gastrointestinal pathology. Well-designed prospective studies to further evaluate the cost-effectiveness of routine gastroscopy in the work up of FIT positivity are warranted to make better clinical practice guidelines.

There Is No Role for Colonoscopy after Diverticulitis among Asian Patients Less than 50 Years of Age

BACKGROUND

Colonoscopy is advocated following acute diverticulitis to ensure that malignancy is not missed. In an Asian population, diverticulitis is more common in the right colon and in younger patients. The purpose of this study is to examine the utility of colonoscopy amongst Asian patients <50 years of age who have had colonic diverticulitis.

METHODS

A retrospective review of all patients aged 50 years and under who were treated for colonic diverticulitis between 2012 and 2014 was performed. All patients were advised to undergo a colonoscopy when the diverticulitis had settled, and findings at colonoscopy were recorded.

RESULTS

Fifty-five patients aged <50 years had acute diverticulitis. Forty-eight (87.3%) had right-sided diverticulitis. Amongst them, 45 (93.8%) had Hinchey 1a, 1b or 2 diverticulitis, while none had Hinchey 4 diverticulitis. Excluding the only patient that underwent a colonic resection, 27 (50.0%) patients returned for a colonoscopy. None of these patients were found to have colorectal cancer or an advanced adenoma. Six (11.1%) of them had adenomas with low-grade dysplasia.

CONCLUSION

Right-sided diverticulitis is more common in the young Asian population. Most patients can be conservatively treated. Follow-up colonoscopy may not be required in these patients.

Liposarcoma of the cord treated with surgery alone: Our experience of five patients

Background:

Liposarcoma of the spermatic cord is a rare condition presenting as an inguinal or scrotal mass. We describe our experience in the management of five patients diagnosed with this disease.

Methods:

We conducted a retrospective analysis of patients who underwent treatment for the condition between 2011 and 2014. Demographic data collected included the patient’s age, presentation, site of tumour, tumour size and grade and World Health Organisation (WHO) histotypes. Adequacy of tumour resection and the use of adjuvant chemotherapy or radiotherapy were also recorded. The study end points included duration of disease-free survival (DFS) as well as overall survival (OS).

Results:

During the study period we identified five patients with a diagnosis of liposarcoma of the cord with a median age of 67 (range 33–72) years. Three patients presented with primary disease and two were diagnosed post-resection and required re-excision to obtain R0 resection margins. Three patients had well-differentiated and two patients had dedifferentiated liposarcoma. None of the patients required adjuvant chemotherapy or radiotherapy following achievement of R0 resection margins and developed loco-regional recurrence or distant metastases. Median DFS was 30 (range 10–45) months.

Conclusion:

Liposarcomas of the cord are rare soft-tissue sarcomas with a high incidence of recurrence. Treatment of choice is radical orchidectomy, wide excision of the tumour and high ligation of the spermatic cord. Long-term follow-up is necessary.

Predictors for outcomes after super-selective mesenteric embolization for lower gastrointestinal tract bleeding

BACKGROUND

The optimal management of bleeding from the lower gastrointestinal tract (LGIB) remains controversial. We aim to evaluate the efficacy of mesenteric embolization for LGIB and to identify predictors for re-bleeding after the procedure.

METHODS

We conducted a retrospective review of all patients who underwent mesenteric embolizations for LGIB in our institution over a 6-year period (from August 2007 to August 2013). Technical success was defined as the absence of contrast extravasation on post-embolization angiogram. Clinical success was defined as the absence of overt LGIB (clinical bleeding with >1 g/dL decrease in haemoglobin) within 30 days post-embolization.

RESULTS

Mesenteric embolization was performed in 26 patients with LGIB. Technical success rate was 100%, with no occurrence of post-embolization ischaemia. Clinical success rate was 65.4%, with nine patients re-bleeding within 30 days post-embolization. Three underwent surgery, one underwent re-embolization and five were treated conservatively. Mortality rate was 19.3% (five patients), with two bleeding-associated mortalities. Site and aetiology of LGIB, platelet count and coagulation status prior to embolization, number of packed red blood cells and fresh frozen plasma transfusion were found to be predictors of clinical failure. After Bonferroni's correction (P < 0.005), platelet count of ≤140 × 10(9) /L prior to embolization was the only statistically significant factor associated with re-bleeding (odds ratio = 17.5, 95% confidence interval: 2.364-129.57; P = 0.004).

CONCLUSION

Mesenteric embolization was found to be safe and effective in treating LGIB (100% technical success, no post-embolization ischaemia), with 65.4% of cases not requiring further intervention. Low platelet count prior to embolization appears to be associated with clinical failure.