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Dive into the research topics where Kok-Yang Tan is active.

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Featured researches published by Kok-Yang Tan.


American Journal of Surgery | 2012

Assessment for frailty is useful for predicting morbidity in elderly patients undergoing colorectal cancer resection whose comorbidities are already optimized

Kok-Yang Tan; Yutaka J. Kawamura; Aika Tokomitsu; Terence Tang

BACKGROUND The clinical syndrome of frailty identified through the assessment of weight loss, gait speed, grip strength, physical activity, and physical exhaustion has been used to identify patients with reduced reserves. We hypothesized that frailty is useful in predicting adverse outcomes in optimized elective elderly colorectal surgery patients. METHODS A prospective study was conducted at 2 centers (Singapore and Japan). All patients over 75 years of age undergoing colorectal resection were assessed for the presence of the syndrome of frailty. All these patients had already had their comorbidities optimized for surgery. The outcome measure was postoperative major complications (defined as Clavien-Dindo type II and above complications). RESULTS Eighty-three patients were studied from February 2008 to April 2010. The mean age was 81.5 years (range 75-93 years). The mean comorbidity index was 3.37 (range 0-11). Twenty-six (31.3%) patients were an American Society of Anesthesiologists (ASA) score of 3 and above. Chi-square analysis revealed that the odds ratio of postoperative major complications was 4.083 (95% confidence interval, 1.433-11.638) when the patient satisfied the criteria for frailty. Albumin <35, ASA >3, comorbidity index >5, and Physiologic and Operative Severity Score for the enUmeration of Mortality and Morbidity (POSSUM) scores were not predictive of postoperative major complications. CONCLUSIONS Preliminary findings show that frailty is a potent adjunctive tool of predicting postoperative morbidity. Frailty can be used to identify elderly patients needing further optimization before major surgery.


World Journal of Gastrointestinal Surgery | 2010

Innovations in chronic anal fissure treatment: A systematic review

Aaron Poh; Kok-Yang Tan; Francis Seow-Choen

A chronic anal fissure is a common perianal condition. This review aims to evaluate both existing and new therapies in the treatment of chronic fissures. Pharmacological therapies such as glyceryl trinitrate (GTN), Diltiazem ointment and Botulinum toxin provide a relatively non-invasive option, but with higher recurrence rates. Lateral sphincterotomy remains the gold standard for treatment. Anal dilatation has no role in treatment. New therapies include perineal support devices, Gonyautoxin injection, fissurectomy, fissurotomy, sphincterolysis, and flap procedures. Further research is required comparing these new therapies with existing established therapies. This paper recommends initial pharmacological therapy with GTN or Diltiazem ointment with Botulinum toxin as a possible second line pharmacological therapy. Perineal support may offer a new dimension in improving healing rates. Lateral sphincterotomy should be offered if pharmacological therapy fails. New therapies are not suitable as first line treatments, though they can be considered if conventional treatment fails.


Colorectal Disease | 2010

Distribution of the first metastatic lymph node in colon cancer and its clinical significance

Kok-Yang Tan; Yutaka J. Kawamura; Ken Mizokami; Junichi Sasaki; Shingo Tsujinaka; Takafumi Maeda; M. Nobuki; Fumio Konishi

Introduction  The pattern of distribution of lymph node metastasis in resected specimens of colon cancer has been rarely reported in the English literature. The aim of this study was to determine the location of the first metastatic lymph node, giving insight into the drainage pattern of colon cancer lymphatics.


Techniques in Coloproctology | 2008

The role of traditional Chinese medicine in colorectal cancer treatment.

Kok-Yang Tan; C. B. Liu; A. H. Chen; Y. J. Ding; H. Y. Jin; F. Seow-Choen; R. J. Nicholls

Surgery, chemotherapy and radiotherapy have been the mainstay of colorectal cancer treatment. There is however current intense research on traditional Chinese medicine (TCM) as novel or additional treatment methods for colorectal cancer. This article reviews the current use of TCM in colorectal cancer so as to increase the awareness of colorectal surgeons. The pathogenesis of colorectal cancer according to TCM is discussed. TCM has been used successfully during the perioperative period to relieve intestinal obstruction, reduce postoperative ileus and reduce urinary retention after rectal surgery. Good results have been reported in the treatment of the complications of chemotherapy and radiation enterocolitis. Favourable results have also been shown in the use of TCM either alone or in combination with chemotherapy to treat advanced colorectal cancer. Molecular studies have shown some TCM compounds to reduce tumour cell proliferation and induce apoptosis. Although the reported results of TCM have been exciting thus far, problems of lack of consensus on treatment regimes and questions on the reliability, validity and applicability of published studies prevent its widespread use. There is now an urgent need for colorectal surgeons to work with TCM physicians in the continuing research on this 6000-yearold art so as to realize its full potential for our patients.


Techniques in Coloproctology | 2008

Randomized clinical trial comparing LigaSure haemorrhoidectomy with open diathermy haemorrhoidectomy

Kok-Yang Tan; Thaw Zin; Hsien-Lin Sim; Philip Poon; Anton Cheng; Kenneth Seck Wai Mak

Background Milligan-Morgan excision haem-orrhoidectomy remains a very popular treatment modality for third and fourth degree haemorrhoids due to its cost effectiveness and good long-term results. The LigaSure tissue-sealing device is an alternative technique used in haemorrhoidectomy that has been shown to produce favourable results. The aim of this study was to assess the effectiveness of the LigaSure tissue sealing device in comparison with conventional diathermy haemorrhoidectomyMethods A prospective clinical trial was conducted. Patients with newly diagnosed haemorrhoids requiring haemorrhoidectomy were randomized to either LigaSure haemorrhoidectomy or diathermy haemorrhoidectomy. Surgical technique and postoperative care was standardized. Outcome measures were operative time and bleeding, postoperative pain (measured on a visual analogue scale) and rate of wound healingResults We randomized 44 patients, 22 to LigaSure and 22 to diathermy; 43 patients were evaluated. They were aged between 19 and 71 years. There were no differences in patient demographics or type of haemorrhoid being operated on. LigaSure haemorrhoidectomy had a significantly lower mean operative time and intraoperative bleeding. At 3 weeks after surgery, haemorrhoidectomy performed with LigaSure had an odds ratio for complete epithelialization of 3.1 over diathermy (95% CI 1.2–8.2). There was no difference in postoperative painConclusion LigaSure haemorrhoidectomy is superior to diathermy for open haemorrhoidectomy


Scandinavian Journal of Surgery | 2012

Proximal bowel necrosis after high ligation of the inferior mesenteric artery in colorectal surgery

Shingo Tsujinaka; Yutaka J. Kawamura; Kok-Yang Tan; Ken Mizokami; Junichi Sasaki; Takafumi Maeda; Yuichi Kuwahara; Fumio Konishi; Alan T. Lefor

Background and Aims High ligation of the inferior mesenteric artery may jeopardize blood supply to the proximal bowel. We undertook this study to review the clinical features and outcomes of patients who developed proximal bowel necrosis after high ligation of the inferior mesenteric artery, and to assess the incidence and the risk factors for this complication. Materials and Methods A retrospective analysis of patients undergoing high or low ligation for sigmoid colon and rectal cancer with a primary anastomosis between April 2004 and March 2009 was performed. Patient and tumor characteristics and the incidence of bowel necrosis were reviewed. Results Four hundred and nine patients were included to the analysis. Six out of 302 patients (2.0%) with high ligation developed proximal bowel necrosis, while the remaining 107 patients with low ligation did not suffer from this complication. All patients who developed proximal bowel necrosis underwent secondary surgery with resection of necrotic bowel. The pathological examination of the resected specimen revealed mucosal to transmural ischemic necrosis without the evidence of vascular thrombosis or embolic occlusion. Univariate analysis revealed that advanced age, cerebrovascular disease, and hypertension were significantly associated with proximal bowel necrosis. Multivariate analysis demonstrated that cerebrovascular disease was an independent predictor of this complication. Of these six patients, two died from associated complications. Conclusions Proximal bowel necrosis after high ligation is potentially fatal, and this report provides a warning in clinical settings where high ligation is indicated. Further studies are warranted to evaluate its distinct relationship with high ligation and to clarify whether low ligation would be a safeguard.


American Journal of Surgery | 2011

Laparoscopic colorectal surgery in elderly patients: a case-control study of 15 years of experience

Kok-Yang Tan; Fumio Konishi; Yutaka J. Kawamura; Takafumi Maeda; Junichi Sasaki; Shingo Tsujinaka; Hisanaga Horie

INTRODUCTION The aim of this study was to review the impact of age (≥75 years) on the short-term outcomes of laparoscopic colorectal surgery. METHODS Three hundred seventy-nine patients under 70 years of age and 91 patients 75 years and older were analyzed. Quantification of comorbidities was performed using the Charlson Weighted Comorbidity Index. Outcome measures were postoperative complications and 30-day mortality. RESULTS There was no difference in the occurrence of postoperative complications between the younger and older patients. Bivariate analysis revealed that patient age was not a risk factor of major complications (odds ratio = 1.2; 95% confidence interval, .6-2.3). Although bivariate analysis revealed that older age had a statistically significant odds ratio for 30-day mortality (odds ratio = 12.8; 95% confidence interval, 1.3-125.4), multivariate analysis revealed that it was a weighted comorbidity index score of 5 or more (P = .02) and long operative time (P = .01) that were independent predictors of 30-day mortality and not age per se. CONCLUSIONS Age is not an independent predictor of morbidity and mortality in laparoscopic colorectal cancer surgery.


Surgery Today | 2010

Long-term results of laparoscopic colorectal cancer resection: current knowledge and what remains unclear.

Kok-Yang Tan; Fumio Konishi

Laparoscopic colorectal cancer resection has advanced considerably since it was first described in 1991. It is becoming increasingly popular, and earlier concerns about its oncologic safety are being dispelled by long-term data, which have emerged over recent years, suggesting that laparoscopic colorectal cancer surgery is not inferior to open surgery. This article reviews our current knowledge of the long-term results of laparoscopic colorectal cancer resection, and addresses what remains unknown and needs to be elucidated.


Surgery Today | 2010

Optimizing the management of elderly colorectal surgery patients

Kok-Yang Tan; Fumio Konishi; Lawrence Tan; Wui-Kin Chin; Hean-Yee Ong; Phyllis Tan

With the ever increasing number of geriatric surgical patients, there is a need to develop efficient processes that address all of the potential issues faced by patients during the perioperative period. This article explores the physiological changes in elderly surgical patients and the outcomes achieved after major abdominal surgery. Perioperative management strategies for elderly surgical patients in line with the practices of the Geriatric Surgical Team of Alexandra Health, Singapore, are also presented. A coordinated transdisciplinary approach best tackles the complexities encountered in these patients.


Langenbeck's Archives of Surgery | 2010

Improving prediction of lateral node spread in low rectal cancers—multivariate analysis of clinicopathological factors in 1,046 cases

Kok-Yang Tan; Seiichiro Yamamoto; Shin Fujita; Takayuki Akasu; Yoshihiro Moriya

IntroductionThis study aims to search for independent predictors of lateral node metastasis in low rectal cancers.Materials and methodsWe analyzed 1,046 patients who underwent curative resection for lower rectal cancer in our prospectively collected database. All lymph nodes were dissected from the fresh specimen, and their locations were documented prospectively according to the classification by the Japanese Society of Cancer of the Colon and Rectum.ResultsMore than 35% of the patients had demonstrated upward nodal metastasis in the direction of the inferior mesenteric vessels, while 11% demonstrated lateral node metastasis, which was present in 17.3% of patients with T3 and T4 lesions. Multivariate analysis revealed five factors to be statistically significant independent predictors of lateral node metastasis: female sex, tumors that were not well differentiated, pathological T3 and above, positive microscopic lymphatic invasion, and positive mesorectal nodes. Using the variables sex, differentiation, T stage, and mesorectal nodes as risk factors, because these could be elucidated preoperatively, the presence of lateral node metastasis was then analyzed according to the number of positive risk factors. When there were fewer than three positive factors, the risk of lateral nodal spread was low (4.5%). When three or more risk factors were positive, the odds of lateral node metastasis were more than 7.5 times higher (p < 0.001).ConclusionThe findings of this study provide a scoring system that can be used to guide the clinician to the presence of lateral node metastasis in low rectal cancers.

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Takafumi Maeda

Jichi Medical University

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Ken Mizokami

Jichi Medical University

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F. Seow-Choen

Singapore General Hospital

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Phyllis Tan

Khoo Teck Puat Hospital

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