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Dive into the research topics where David S. Chan is active.

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Featured researches published by David S. Chan.


British Journal of Surgery | 2013

Systematic review and meta-analysis of the influence of circumferential resection margin involvement on survival in patients with operable oesophageal cancer

David S. Chan; T.D. Reid; I. Howell; Wyn G. Lewis

The prognostic role and definition of circumferential resection margin (CRM) involvement in operable oesophageal cancer remain controversial. The College of American Pathologists (CAP) and Royal College of Pathologists (RCP) define CRM involvement as tumour found at the cut resection margin and within 1 mm of the cut margin respectively. This systematic review and meta‐analysis was performed to determine the influence of CRM involvement on survival in operable oesophageal cancer.


Histopathology | 2009

The assessment of prognosis of surgically resected oesophageal cancer is dependent on the number of lymph nodes examined pathologically

Christopher P. Twine; Wyn G. Lewis; Matthew A. Morgan; David S. Chan; Geoffrey W. B. Clark; Tim Havard; Thomas Crosby; S. Ashley Roberts; Geraint T. Williams

Aims:  The prognosis in surgically resected oesophageal carcinoma (OC) is dependent on the number of regional lymph nodes (LN) involved, but no guidance exists on how many LNs should be examined histopathologically to give a reliable pN status. The aim of this study was to determine whether the number of LNs examined after OC resection has a significant effect on the assessment of prognosis.


European Journal of Radiology | 2014

Prognostic significance of novel 18F-FDG PET/CT defined tumour variables in patients with oesophageal cancer

K.G. Foley; Patrick Fielding; Wyn G. Lewis; Alex Karran; David S. Chan; Paul A. Blake; S. Ashley Roberts

PURPOSE (18)F-fluorodeoxyglucose ((18)F-FDG) positron emission tomography (PET) combined with computed tomography (PET/CT) is now established as a routine staging investigation of oesophageal cancer (OC). The aim of the study was to determine the prognostic significance of PET/CT defined tumour variables including maximum standardised uptake value (SUVmax), tumour length (TL), metastatic length of disease (MLoD), metabolic tumour volume (MTV), total lesion glycolysis (TLG) and total local nodal metastasis count (PET/CT LNMC). MATERIALS AND METHODS 103 pre-treatment OC patients (76 adenocarcinoma, 25 squamous cell carcinoma, 1 poorly differentiated and 1 neuroendocrine tumour) were staged using PET/CT. The prognostic value of the measured tumour variables were tested using log-rank analysis of the Kaplan-Meier method and Coxs proportional hazards method. Primary outcome measure was survival from diagnosis. RESULTS Univariate analysis showed all variables to have strong statistical significance in relation to survival. Multivariate analysis demonstrated three variables that were significantly and independently associated with survival; MLoD (HR 1.035, 95% CI 1.008-1.064, p=0.011), TLG (HR 1.002, 95% CI 1.000-1.003, p=0.018) and PET/CT LNMC (HR 0.048-0.633, 95% CI 0.005-2.725, p=0.015). CONCLUSION MLoD, TLG, and PET/CT LNMC are important prognostic indicators in OC. This is the first study to demonstrate an independent statistical association between TLG, MLoD and survival by multivariable analysis, and highlights the value of staging OC patients with PET/CT using functional tumour variables.


British Journal of Surgery | 2014

Propensity score analysis of oesophageal cancer treatment with surgery or definitive chemoradiotherapy

Alex Karran; Paul A. Blake; David S. Chan; T.D. Reid; I. L. Davies; M. Kelly; S. A. Roberts; Tom Crosby; Wyn G. Lewis

The role of treatments involving surgery versus definitive chemoradiotherapy (dCRT) for oesophageal cancer remains controversial.


Scandinavian Journal of Gastroenterology | 2007

Influence of socio-economic deprivation on outcomes for patients diagnosed with oesophageal cancer.

M. A. Morgan; Wyn G. Lewis; David S. Chan; Sarah Burrows; Michael R. Stephens; S. Ashley Roberts; Timothy Havard; Geoffrey W. B. Clark; Tom Crosby

Objective. To determine the influence of deprivation on outcomes for patients with oesophageal cancer. Material and methods. A total of 1196 consecutive patients with oesophageal carcinoma presenting to a regional multidisciplinary team between 1 January 1998 and 31 August 2005 were studied prospectively and deprivation scores calculated using the Indices of Multiple Deprivation (IMD) of the National Assembly for Wales. The patients were subdivided into quintiles for analysis. Results. Inhabitants of the most deprived areas (quintile 5) were younger at presentation (median age 67 years versus 70 years, p=0.01) and were more likely to have squamous cell carcinomas (SCCs) (p=0.002) in comparison with patients from the least deprived areas (quintile 1). Stage of disease and morbidity did not correlate with deprivation quintile, but operative mortality was greater in quintile 1 versus 5 (1.9% versus 5.8%, p=0.281). Overall 5-year survival for those patients undergoing oesophagectomy was unrelated to deprivation quintile (1 versus 5, 24% versus 33%, p=0.8246), but was lower following definitive chemoradiotherapy (dCRT) for the least deprived quintiles (1, 2 & 3 versus 4 & 5, 35% versus 16%, p=0.0272). Conclusions. Although deprivation was associated with younger age, SCC and a trend towards higher operative mortality, survival after diagnosis and oesophagectomy were unrelated to deprivation.


Clinical Radiology | 2014

N-staging of oesophageal and junctional carcinoma: is there still a role for EUS in patients staged N0 at PET/CT?

K.G. Foley; Wyn G. Lewis; Patrick Fielding; Alexandra Karran; David S. Chan; Paul A. Blake; S. A. Roberts

AIM To assess whether separate endoscopic ultrasound (EUS) lymph node (N)-staging is still of prognostic value in those staged node negative (N0) at combined positron-emission tomography/computed tomography (PET/CT) in patients with oesophageal cancer (OC). MATERIALS AND METHODS One hundred and seventeen consecutive patients [median age 67 years; 88 male; 98 cases of adenocarcinoma, 19 cases of squamous cell carcinoma (SCC)] staged as N0 at PET/CT underwent EUS to record tumour (T)- and N-stage. The patients were subsequently separated into two groups: EUS N0 (n = 78) and EUS N+ (n = 39). Survival analysis using Kaplan-Meier and Coxs proportional hazard methods was performed. Primary outcome was overall survival from diagnosis. RESULTS EUS N-stage and EUS N0 versus EUS N+ (p = 0.005 and p = 0.001, respectively) were found to be significantly and independently associated with survival in two models of multivariate analysis, in patients staged N0 at PET/CT. EUS T-stage was significantly associated with survival on univariate analysis. CONCLUSION EUS N-staging still has prognostic value in patients staged N0 at PET/CT. There is a significant difference in survival between EUS N0 and positive nodal EUS status in those staged N0 at PET/CT, suggesting PET/CT is unreliable for local staging. PET/CT and EUS continue to have complimentary roles in OC staging.


Journal of Cancer Education | 2012

Relative Quality of Internet-Derived Gastrointestinal Cancer Information

David S. Chan; Anita Willicombe; T.D. Reid; Ceri Beaton; David T Arnold; James Ward; I. Llion Davies; Wyn G. Lewis

Internet-derived health care information is increasingly accessed by patients, yet its quality and accuracy is variable and unregulated. The aim of this study was to assess the information available regarding common gastrointestinal cancers via three internet search engines (Google, Yahoo and Bing). The top 30 websites for each of the terms: oesophageal, gastric, pancreatic, colon and rectal cancer were evaluated (University of Michigan Consumer Health Website Checklist) and scored [−80 (poor) to 90 (excellent)]. The median score was 53 (−7 to 81) and was significantly higher for oesophageal (61) and pancreatic (65) cancer websites, compared with gastric (49), colon (48) and rectal cancer (50) (p = 0.014). Median scores related to charitable organisations were significantly better than academic, commercial, news agency, care provider, layperson and medical information websites collectively (79 vs. 42, p < 0.0001). Overall quality of internet-derived gastrointestinal cancer information remains poor and patients and clinicians should be aware.


Clinical Oncology | 2013

Influence of a Regional Centralised Upper Gastrointestinal Cancer Service Model on Patient Safety, Quality of Care and Survival

David S. Chan; T.D. Reid; C. White; A. Willicombe; G. Blackshaw; G. W. B. Clark; Timothy Havard; X. Escofet; Tom Crosby; S. A. Roberts; Wyn G. Lewis

AIMS The aim of this study was to determine outcomes of a reconfigured centralised upper gastrointestinal (UGI) cancer service model, allied to an enhanced recovery programme, when compared with historical controls in a UK cancer network. MATERIALS AND METHODS Details of 606 consecutive patients diagnosed with UGI cancer were collected prospectively and outcomes before (n = 251) and after (n = 355) centralisation compared. Primary outcome measures were rates of curative treatment intent, operative morbidity, length of hospital stay and survival. RESULTS The rate of curative treatment intent increased from 21 to 36% after centralisation (P < 0.0001). Operative morbidity (mortality) and length of hospital stay before and after centralisation were 40% (2.5%) and 16 days, compared with 45% (2.4%) and 13 days, respectively (P = 0.024). The median and 1 year survival (all patients) improved from 8.7 months and 39.0% to 10.8 months and 46.8%, respectively, after centralisation (P = 0.032). On multivariate analysis, age (hazard ratio 1.894, 95% confidence interval 0.743-4.781, P < 0.0001), centralisation (hazard ratio 0.809, 95% confidence interval 0.668-0.979, P = 0.03) and overall radiological TNM stage (hazard ratio 3.905, 95% confidence interval 1.413-11.270, P < 0.0001) were independently associated with survival. CONCLUSION These outcomes confirm the patient safety, quality of care and survival improvements achievable by compliance with National Health Service Improving Outcomes Guidance.


Endoscopy | 2018

Systematic review and meta-analysis of the effectiveness of radiofrequency ablation in low grade dysplastic Barrett’s esophagus

Gargi Pandey; Mubashir Mulla; Wyn G. Lewis; Antonio Foliaki; David S. Chan

BACKGROUND Barretts esophagus (BE) is a premalignant condition characterized by replacement of the esophageal lining with metastatic columnar epithelium, and its management when complicated by low grade dysplasia (LGD) is controversial. This systematic review and meta-analysis aimed to determine the efficacy of radiofrequency ablation (RFA) in patients with LGD. METHODS MEDLINE, EMBASE, and Web of Science were searched for studies including patients with BE-associated LGD receiving RFA (January 1990 to May 2017). The outcome measures were complete eradication of intestinal metaplasia (CE-IM) and dysplasia (CE-D), rates of progression to high grade dysplasia (HGD) or cancer, and recurrence. RESULTS Eight studies including 619 patients with LGD (RFA = 404, surveillance = 215) were analyzed. After a median follow-up of 26 months (range 12 - 44 months), the overall pooled rates of CE-IM and CE-D after RFA were 88.17 % (95 % confidence interval [CI] 88.13 % - 88.20 %; P < 0.001) and 96.69 % (95 %CI 96.67 % - 96.71 %; P < 0.001), respectively. When compared with surveillance, RFA resulted in significantly lower rates of progression to HGD or cancer (odds ratio [OR] 0.07, 95 %CI 0.02 - 0.22). The pooled recurrence rates of IM and dysplasia were 5.6 % (95 %CI 5.57 - 5.63; P < 0.001) and 9.66 % (95 %CI 9.61 - 9.71; P < 0.001), respectively. CONCLUSIONS RFA safely eradicates IM and dysplasia and reduces the rates of progression from LGD to HGD or cancer in the short term.


Surgeon-journal of The Royal Colleges of Surgeons of Edinburgh and Ireland | 2014

Recent trends in thyroid surgery in Wales

David S. Chan; Onyebuchi E. Okosieme

INTRODUCTION Our objective was to analyse trends in thyroid surgery in Wales over a recent 12-year period. METHODS Details of patients who underwent thyroid surgery across Wales from 1999 to 2010 were analysed from the Patient Episodes Database for Wales [n = 6570, 83% (5429) female, 86% (5634) benign thyroid disease]. We determined age-adjusted thyroidectomy rates from the European standard population and a Poisson regression model was fitted to assess temporal trends. Joinpoint regression was used to calculate annual percentage change (APC) in thyroidectomy rates. RESULTS An increase in thyroidectomy rates was observed for malignant disease [APC 4.5, 95% confidence interval (CI) 1.6-7.5] while surgery rates for benign disease declined over the period (APC -3.2, 95% CI -5.1 to -1.3). The use of total thyroidectomy rose from 17% (599/3501) in 1999-2004 to 30% (912/3069) in 2005-2010 (p < 0.001). Total thyroidectomies were performed in a higher proportion of males than females [26% (291/1141) vs. 22% (1220/5429), p = 0.03] and in a greater percentage of patients with malignant disease than benign [36% (337/936) vs. 21% (1174/5634), p < 0.001). General surgeons undertook 83% of thyroid surgery but with a growing involvement of ENT surgeons. Regional disparities were seen in the type of surgery offered to patients with benign thyroid disease. CONCLUSION The use of total thyroidectomy for benign and malignant thyroid disease has risen in Wales. The increase in surgeries performed for malignancy would support a rising incidence of thyroid cancer in the region. Regional disparities in choice of surgery for benign disease require further exploration.

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Geoffrey W.B. Clark

University of Southern California

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