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F Seow-Choen

Publications and source records attributed to F Seow-Choen.

At least 73 records · Page 4Linked to original sources
PubMed2001

Primary anorectal malignant melanoma: clinical features and results of surgical therapy in Singapore--a case series.

INTRODUCTION: Primary malignant melanoma arising from the anorectum is uncommon. The natural history of anorectal malignant melanoma is that of a very poor prognosis with early dissemination of disease. Successful surgical treatment has been rare. The present series reviews the clinical features and results of surgical management of patients with anorectal malignant melanoma treated in the Department of Colorectal Surgery, Singapore General Hospital. MATERIALS AND METHODS: Data for all patients treated for anorectal malignant melanoma during an 11-year period from 1989 to 1999 were reviewed. The age, sex, presenting symptoms, duration of symptoms prior to diagnosis, size of tumour, extent of disease, type of surgery and length of survival were analysed. RESULTS: Four men and 2 women, ranging in age from 31 to 81 years with histologically proven primary anorectal malignant melanoma, were included in the study. The most common (67%) presenting symptom was rectal bleeding. The mean tumour size was 2.5 cm (range 1 to 5 cm). All underwent abdomino-perineal resection. Three died of disseminated disease within 17 months while the other 3 were still alive at the time of this study; the longest up to 6.5 years from the time of diagnosis. CONCLUSION: The prognosis of primary anorectal malignant melanoma is poor. However, it is worthwhile treating aggressively as long-term survivor may be encountered in some.

Adult↗
PubMed2000

Down-regulation of p27 is a significant predictor of poor overall survival and may facilitate metastasis in colorectal carcinomas.

The p27 gene product has been shown to have prognostic significance in a range of tumors. Down-regulation of p27 has also been implicated in loss of cell adhesion in tumor cells. Our study aimed to investigate whether p27 expression was significantly correlated with overall survival of colorectal carcinoma patients in the Singapore population, which is predominantly Chinese. Staining was performed on 136 paraffin-embedded specimens collected between 1991 and 1992 using an anti-p27 monoclonal antibody. Follow-up of patients was until time of death or for 5 years. There was a significant association between overall survival and p27 expression for all specimens. However, there was no significant correlation between p27 expression and other clinical features such as gender, age, tumor stage, differentiation, and site. When stratified by tumor stage, patients whose tumors exhibited higher metastatic potential (stage III/IV) but had strong p27 expression had a median survival that was 23 months longer than stage III/IV patients whose tumors had no or weak p27 expression. Our results thus suggest that one potential mechanism of action of p27 is to suppress metastasis possibly through its involvement in cell adhesion.

Age Factors↗
PubMed2000

Preservation of rectal function after low anterior resection with formation of a neorectum.

Recent advances in surgery have enabled low rectal cancers to be resected, while at the same time restoring bowel continuity and preserving the anal sphincter. Although a permanent stoma is avoided and the operation is oncologically sound, function may be compromised. Many patients with a straight coloanal anstomosis suffer from urgency, incontinence, and bowel frequency-the so-called anterior resection syndrome. Over the last 15 years, surgical developments have aimed at improving function after restoration of bowel continuity, essentially by creating a neorectum. The best known and most widely practiced operation involves formation of a colonic J-pouch. The physiological and functional outcomes of the colonic J-pouch are discussed, along with controversies surrounding construction. Although a J-pouch improves some aspects of function, the results are not perfect. Alternatives to the colonic J-pouch are appraised, indicating future areas of development.

Anastomosis, Surgical↗
PubMed2000

Postoperative intra-abdominal free gas after open colorectal resection.

PURPOSE: An erect chest radiograph for subdiaphragmatic free gas can be a useful adjunct in detecting a defect in gastrointestinal continuity. The usefulness of this test after laparotomy has not been defined, because the period of persistence of free gas is unknown. We set out to determine the length of time for natural absorption of postlaparotomy pneumoperitoneum in a prospective cohort study. METHOD: Plain erect chest radiographs were performed on the second and fourth postoperative day and daily thereafter until the disappearance of subdiaphragmatic free gas after laparotomy. RESULTS: Seventy-five consecutive patients were studied after informed consent. The mean age was 62.1 (standard error of the mean, 1.7) years. On the fifth postoperative day, sixth postoperative day, and seventh postoperative day, 71.6, 80, and 89 percent of patients, respectively, had no visible subdiaphragmatic gas. Five patients had gas persisting beyond the tenth postoperative day. Two of these patients did not have an anastomosis. The use of drainage tubes did not affect significantly the mean time to disappearance of subdiaphragmatic free gas (4.5 vs. 4.9 days; P = 0.45: t-test). The duration of surgery, body mass index, and time to resume bowel function had no significant effect on gas disappearance. Two patients had a clinical leak on the fifth postoperative day. This was manifested as an increase in the collection of subdiaphragmatic gas during the course of a day. CONCLUSION: By the sixth postoperative day 80 percent of patients had no subdiaphragmatic free gas on an erect chest radiograph regardless of the presence of a drainage tube. The erect chest radiograph may therefore be a simple and readily available adjunct in the evaluation of postoperative abdominal pain, especially after the sixth postoperative day when a similar prior examination is done routinely on the fourth postoperative day for comparison.

Anastomosis, Surgical↗
PubMed2000

Tuberculous anal sepsis: report of clinical features in 20 cases.

INTRODUCTION: Tuberculosis is a neglected cause of anal sepsis, often is not recognized, and therefore is not treated properly. METHOD: All patients were reviewed who had tuberculous anal sepsis diagnosed by histology reports of fistulectomy specimens or abscess scrapings from January 1990 to April 1999. RESULTS: Twenty patients (median age, 53 years; 18 males) with anal tuberculous sepsis were identified. They presented with abscesses (n = 2), abscesses and fistulas (n = 6), or fistulas (n = 12). All patients had a long history of anal complaints (3 months to 20 years), for which 15 patients were operated on previously. Nearly all fistulas (17/18) were complex, and secondary tracks or additional complicating features were common, even at first presentation. Eight patients had active concurrent pulmonary tuberculosis, and six showed evidence of previous pulmonary tuberculosis. Six patients had no signs of concurrent or previous tuberculosis elsewhere. Recurrence was observed only in cases where tuberculosis was initially not recognized, and antitubercular treatment therefore was not started. CONCLUSION: Contrary to views held previously, anal tubercular sepsis seems to have characteristic clinical features. It should be considered in cases of known pulmonary or extrapulmonary tuberculosis or if anal sepsis is persistent, recurrent, or complex in nature.

Adult↗
PubMed2000

Stapled hemorrhoidectomy--cost and effectiveness. Randomized, controlled trial including incontinence scoring, anorectal manometry, and endoanal ultrasound assessments at up to three months.

PURPOSE: Stapled hemorrhoidectomy is performed without leaving painful perianal wounds. The aim of this study was to assess any benefits, compared with a conventional open diathermy technique. METHODS: A total of 119 consecutive patients with prolapsed irreducible hemorrhoids were randomly assigned (conventional open diathermy technique = 62; stapled hemorrhoidectomy = 57). Preoperative fecal incontinence scoring, anorectal manometry, and endoanal ultrasound were performed. Postoperatively, these were repeated at up to three months with pain scores, analgesic requirements, quality of life assessment, and total related medical costs. RESULTS: Conventional open diathermy technique was quicker to perform (mean, 11.4 (standard error of the mean, 0.9) vs. 17.6 (3.1) minutes). Hospitalization was similar, but conventional open diathermy technique patients felt more pain during defecation (5.1 (0.4) vs. 2.6 (0.4); P < 0.005) at two weeks, and analgesic requirements were more for up to six weeks (P < 0.05). Up to the latter, 85.5 percent conventional open diathermy technique wounds remained unhealed, with more bleeding (33 (53.2 percent) vs. 19 (33.3 percent); P < 0.05) and pruritus (27 (43.5 percent) vs. 9 (15.8 percent); P < 0.05). Total complication rates were similar (conventional open diathermy technique 16 (25.8 percent) vs. stapled hemorrhoidectomy 10 (17.5 percent)), including mild strictures and bleeding in both groups. Minor incontinence occurred postoperatively in two conventional open diathermy technique and two stapled hemorrhoidectomy patients at six weeks. Endoanal ultrasound internal anal sphincter defects were found in the incontinent conventional open diathermy technique patients, but were asymptomatic in another one conventional open diathermy technique and one stapled hemorrhoidectomy. Only one patient (conventional open diathermy technique with internal sphincter defect) remained incontinent at three months. Changes between preoperative and postoperative anorectal manometry were similar in the two groups. Patients' satisfaction scores and quality of life assessments were also similar. Conventional open diathermy technique patients resumed work later (mean 22.9 (1.8) vs. 17.1 (1.9) days; P < 0.05), but the total costs incurred were less ($921.17 (16.85) vs. $1,283.09 (31.59); P < 0.005). CONCLUSIONS: Stapled hemorrhoidectomy is a safe and effective option in treating irreducible prolapsed piles. It is more expensive but less painful, with less time needed off work. Nonetheless, long-term results are still awaited.

Adult↗
PubMed2000

Anal sphincter injuries from stapling instruments introduced transanally: randomized, controlled study with endoanal ultrasound and anorectal manometry.

PURPOSE: Injury sustained from the transanally introduced stapling technique was assessed by comparison with biofragmentable anastomotic ring anastomosis, which excluded anal manipulation. METHODS: A randomized, controlled trial was conducted on consecutive patients undergoing sigmoid colectomy (where pelvic nerve injury was avoided). A bowel function questionnaire was administered six months after surgery. Anorectal manometry and endoanal ultrasonography were performed preoperatively and at six months postoperatively. The observers were blinded to the randomization. RESULTS: There were 18 patients in the transanally introduced stapling technique group and 17 patients in the biofragmentable anastomotic ring group, with no differences in age, gender, Dukes staging, and follow-up. Three of the transanally introduced stapling technique patients had occasional liquid soiling, which was absent in biofragmentable anastomotic ring patients. Mean change in resting anal pressures was also significantly impaired when compared with patients with biofragmentable anastomotic ring (P = 0.007). Endosonographic internal sphincter fragmentation was found in five transanally introduced stapling technique patients but none after biofragmentable anastomotic ring anastomosis (P = 0.046). Internal sphincter fragmentation was associated with the impaired resting pressures (P = 0.007). External sphincter deficiencies were found after transanally introduced stapling technique in two patients (biofragmentable anastomotic ring = 0), and these were associated with the soiling (P = 0.005). CONCLUSIONS: The transanally introduced stapling technique may result in anal sphincter defects and impaired anal pressures when assessed at six months of follow-up.

Adenocarcinoma↗
PubMed2000

Micronized purified flavonidic fraction compared favorably with rubber band ligation and fiber alone in the management of bleeding hemorrhoids: randomized controlled trial.

PURPOSE: The aim of this study was to assess the role of micronized purified flavonidic fraction in the management of bleeding nonprolapsed hemorrhoids. METHODS: Patients were randomly assigned to receive ispaghula husk alone, rubber band ligation plus ispaghula husk, or micronized purified flavonidic fraction plus ispaghula husk. Other colorectal diseases were excluded by colonoscopy. Blinded observers noted the time for bleeding to stop completely, recurrences, and treatment complications. RESULTS: A total of 162 patients were randomly assigned with no significant differences in the age and gender distributions among the groups. Hemorrhoidal bleeding was relieved most expediently in the micronized purified flavonidic fraction plus ispaghula husk group (ispaghula husk alone n = 66, mean (standard error of the mean) 10.6 (2.3) days; rubber band ligation plus ispaghula husk n = 57, 5.6 (1.1) days; micronized purified flavonidic fraction plus ispaghula husk n = 39, 3.9 (1.2) days; P = 0.03). However, there were no significant differences in the recurrences at six months of follow-up (ispaghula husk alone n = 8 (12 percent); rubber band ligation plus ispaghula husk n = 12 (21 percent); micronized purified flavonidic fraction plus ispaghula husk n = 2 (5.1 percent); P = 0.075). No complications or side-effects were noted. CONCLUSIONS: micronized purified flavonidic fraction used with fiber supplements rapidly and safely relieved bleeding from nonprolapsed hemorrhoids.

Adult↗
PubMed2000

Ambulatory manometry in patients with colonic J-pouch and straight coloanal anastomoses: randomized, controlled trial.

PURPOSE: Bowel function after ultralow anterior resection may be improved by a colonic J-pouch. The aim of this study was to compare the bowel function and ambulatory manometry in patients randomly assigned to straight coloanal anastomosis or colonic J-pouch. METHODS: Forty-seven consecutive patients underwent ultralow anterior resection for adenocarcinoma. The colonic J-pouch was constructed with 6-cm limbs. A bowel function questionnaire was administered at one year after surgery. Ambulatory manometry was performed before and at one year after surgery. RESULTS: Values are expressed below as mean and (standard error of the mean). Patients with colonic J-pouch were found to have less frequent stools (4.6 (0.3) vs. 7.1 (0.9) stools/day; P < 0.05) and stool clustering (35 vs. 63.2 percent; P < 0.05) and were less unlikely to soil when passing flatus (85 vs. 35.3 percent; P < 0.05). The ambulatory anorectal pressure gradient was better preserved in the colonic J-pouch group (30.3 (3.7) vs. 18 (2.6) mmHg; P < 0.05). Stool frequency was predicted by the mean rectal pressures (t = 3.368; P = 0.003). However, higher mean rectal pressures were tolerated by the colonic J-pouch for each daily bowel movement (6.7 (0.6) vs. 4.4 (0.5) mmHg/stool; P = 0.008). Anal sampling episodes and slow wave activity were impaired postoperatively in both groups. The minimal anal pressures were lower in patients unable pass flatus without soiling (12.4 (5.3) vs. 26 (2.3) mmHg; P = 0.004). Large contraction waves were not seen, and this may be related to the absence of severe defecation problems with 6-cm colonic J-pouches. CONCLUSIONS: A colonic J-pouch resulted in better bowel function and more favorable ambulatory manometric findings at one year of follow-up.

Adenocarcinoma↗
PubMed2000

APC mutation and phenotypic spectrum of Singapore familial adenomatous polyposis patients.

Familial adenomatous polyposis (FAP) is a familial form of colon cancer caused by mutation of the adenomatous polyposis coli (APC) gene. Although the APC gene has been extensively studied in the Caucasian population, it has not been previously described in the Chinese population. In the present study, we investigated APC mutation and phenotypic spectrum in the Singapore FAP families who are predominantly Chinese. The protein truncation test (PTT) was used to screen the entire APC gene for germline mutations in 28 unrelated families. Fifteen different mutations were identified in 22 families. Eight mutations were 1-11 basepair deletions or insertions; three involved deletions of whole exons and four were nonsense mutations. Nine of the mutations, including two complex rearrangements, are novel. Eight families including three de novo cases have the same (AAAGA) deletion at codon 1309, indicating that like the Western families, codon 1309 is also the mutation 'hot spot' for Singapore FAP families. In contrast, we did not find any mutation in codon 1061, the second hot spot for the Western population. Congenital hypertrophy of the retinal pigment epithelium (CHRPE) is consistently associated with the prescribed domain (codons 463 to 1387) and is the only phenotype with no intra-family variation. Other than CHRPE, differences in the type and frequency of extracolonic manifestations within the FAP families suggest the influence of modifying genes and environmental factors.

Adenomatous Polyposis Coli↗
PubMed2000

Randomized clinical trial of haemorrhoidectomy under a mixture of local anaesthesia versus general anaesthesia.

BACKGROUND: Application of a topical anaesthetic agent may facilitate infiltration of local anaesthetic at haemorrhoidectomy. METHODS: A randomized clinical trial of 53 consecutive patients requiring elective haemorrhoidectomy was carried out. One group underwent haemorrhoidectomy under general anaesthesia, while the second group had topical anaesthetic cream (containing lignocaine and prilocaine) applied followed by local anaesthetic infiltration for surgical anaesthesia. RESULTS: There were no differences between the two groups in terms of operating time, postoperative pain, nausea or vomiting, pain-free interval after operation, analgesic requirements or patients' satisfaction with the method of anaesthesia. Postoperative oxygen saturation and pulse rate were similar in the two groups. CONCLUSION: Topical anaesthetic and local anaesthesia can be used effectively for haemorrhoidectomy and provide an alternative to general anaesthesia.

Adult↗
PubMed2000

Detailed deletion mapping at chromosome 11q23 in colorectal carcinoma.

Loss of heterozygosity (LOH) is frequent at the chromosomal region 11q22-q23 in several types of tumours of diverse cell origin. Previous investigations of LOH at this chromosomal region in colorectal carcinoma have been contradictory in their findings, and have only included between 1-4 loci. In order to define any regions of LOH on 11q23, we investigated 16 loci between D11S940 and D11S934 on the long arm of chromosome 11 using microsatellite analysis. Of 57 colorectal carcinomas specimens, 36 (63.2%) demonstrated LOH at one or more marker, with the highest frequencies of LOH at D11S1340 (41.0%), located between 105.13-111.97 Mb from the centromere, and D11S924 (37.1%) and D11S4107 (40.5%), both located approximately 113 Mb from the centromere. No statistically significant associations between LOH and age-of-presentation or Dukes' stage were found. LOH was observed in colorectal tumours of all Dukes' stages, including Dukes' stages A and B, suggesting that the inactivation of a tumour suppressor gene(s) on 11q23 occurs in the early stages of colorectal carcinoma. These results confirm the presence of putative tumour suppressor gene(s) at chromosome 11q23, involved in the carcinogenesis of colorectal carcinoma, and will facilitate future identification of candidate genes.

Adenocarcinoma↗
PubMed1999

Microsatellite instability and aneuploidy rate in young colorectal-cancer patients do not differ significantly from those in older patients.

DNA and chromosomal instabilities are thought to promote colorectal carcinogenesis. Mismatch repair (MMR) deficiency affects DNA-sequence integrity, resulting in microsatellite instability (MI). Tumor aneuploidy (AN) has been shown to reflect underlying chromosomal instability (CI). This study aimed at assessing the MI and AN rate of Singapore's colorectal-cancer (CRC) patients, who are predominantly Chinese, in association with age group, tumor site, Dukes' staging and gender. In contrast to a Caucasian series, the MI rate for our younger patients aged 40 or less without family history (23%) is not significantly different from that for older, sporadic patients (13%) aged 60 or more, suggesting that population screening for germline MMR mutations is unlikely to be cost-effective. Our MI-positive patients also show no significant differences from the MI-negative patients with respect to tumor site, staging, ploidy status and gender. This implies that the local MI-positive individuals may have a different profile from that of the Caucasians, indicating the possibility of underlying genetic differences. AN is also not significantly more prevalent in younger patients. In addition, a significant 21% of our patients (p < 0.00005) show no evidence of either the MI or CI pathways, implying that there is at least a third pathway driving colorectal carcinogenesis, involving neither genes that maintain DNA sequence stability nor genes that cause gross chromosomal segregation defects.

Adult↗
PubMed1999

Germline mutations are frequent in the APC gene but absent in the beta-catenin gene in familial adenomatous polyposis patients.

Inactivation of the adenomatous polyposis coli (APC) gene has been shown to initiate the majority of colorectal cancer (CRC), including a familial form called familial adenomatous polyposis (FAP). One consequence of the APC mutation is the activation of the beta-catenin (CTNNB1)/T-cell transcription factor (Tcf) pathway. A recent study has shown that about half of the sporadic CRC lacking APC mutation has CTNNB1 mutation, suggesting that CTNNB1 mutation can substitute for APC mutation in the initiation of colorectal tumorigenesis. However, the frequency of CTNNB1 germline mutation in FAP has not been reported. In the present study, we investigated the frequencies of APC and CTNNB1 germline mutations in 26 unrelated FAP families. We used the Protein Truncation Test (PTT) to screen the entire coding region of APC and found germline mutations in twenty families. We then screened for CTNNB1 germline mutations in the rest of the families lacking detectable APC mutations. No missense mutations at GSK-3beta phosphorylation sites or interstitial deletion of exon 3 of CTNNB1 was found. Our results indicate that APC germline mutations are frequent but CTNNB1 germline mutations are rare in FAP patients, suggesting that CTNNB1 mutation cannot substitute for APC mutation in the initiation of FAP. Genes Chromosomes Cancer 25:396-398, 1999.

Adenomatous Polyposis Coli↗
PubMed1999

Anal pressures impaired by stapler insertion during colorectal anastomosis: a randomized, controlled trial.

PURPOSE: The significance of anal sphincter injury from transanal inserted staplers was studied. A randomized, controlled comparison was made of anorectal manometry and clinical function after sigmoid colectomy (avoiding nerve injury from rectal mobilization), anastomosed by either transanal inserted stapler or biofragmentable anastomotic ring (avoiding anal manipulation). METHOD: Fifty-eight consecutive patients with sigmoid adenocarcinoma were randomly assigned to transanal inserted stapler or biofragmentable anastomotic ring groups. Anorectal manometry and clinical bowel function assessment were performed by an independent blinded observer before surgery and six weeks and six months after surgery. RESULTS: At six weeks after surgery, there was significant impairment of mean anal resting pressures (mean impairment, 23 percent; P < 0.001) and physiologic anal length (mean impairment, 31 percent; P < 0.01) in the transanal inserted stapler group (27 completed the trial), but not in the biofragmentable anastomotic ring group (18 completed the trial). Pressures remained impaired at six months. When changes in the anal pressures were compared between groups, the mean anal resting pressure (P < 0.001) and maximum squeeze pressure (P < 0.01) at six weeks and mean anal resting pressure at six months (P < 0.01) were significantly more impaired in the transanal inserted stapler group. Postoperative bowel function was not different between the two groups. Postoperative complications were similar. In the transanal inserted stapler group one patient died of anastomotic leak sepsis and one had wound infection; in the biofragmentable anastomotic ring group one patient died of myocardial infarct and one had wound infection. CONCLUSION: Direct injuries to the internal anal sphincter occurred after transanal inserted stapler but not biofragmentable anastomotic ring anastomoses. Clinical function was not correspondingly affected, probably because of the adequate residual rectal reservoir after sigmoid colectomy.

Adenocarcinoma↗
PubMed1999

Randomized, controlled trial of low molecular weight heparin vs. no deep vein thrombosis prophylaxis for major colon and rectal surgery in Asian patients.

PURPOSE: Routine deep venous thrombosis prophylaxis is controversial in Asian patients, because deep venous thrombosis incidence was considered negligible. Because of recent reports of significantly higher incidences, a randomized, controlled trial was conducted to assess the effectiveness and complications of enoxaparin prophylaxis (low molecular weight heparins) in major colorectal surgery. METHODS: Three hundred twenty consecutive patients were randomly assigned to control or low molecular weight heparins groups. Patients in the low molecular weight heparins group were given perioperative enoxaparin starting 12 hours before surgery. The surgeon (blinded) assessed for difficulties related to possible enoxaparin administration. Independent blinded observers performed daily clinical assessments and Doppler studies (at the 3rd and 5th postoperative day). Deep venous thrombosis was confirmed by duplex ultrasound, and pulmonary embolism was confirmed by lung scans or postmortem examinations. RESULTS: Deep venous thrombosis developed in 5 of 169 (3 percent) controls and 0 of 134 low molecular weight heparins patients (P = 0.045). Three of the deep venous thrombosis patients had pulmonary embolism, which was fatal in one patient. The surgeons were unable to perceive any increased surgical difficulties in the low molecular weight heparins group. The bleeding-related complications were significantly higher in the low molecular weight heparins patients (controls, n = 3 (1.8 percent); low molecular weight heparins, n = 9 (6.7 percent)). However, apart from one subdural hematoma and two abdominal hemorrhages needing re-exploration, which also occurred in one of the controls, these complications were minor bruises at the wounds, drains, or injection sites. CONCLUSION: Deep venous thrombosis prophylaxis is needed in Asian patients undergoing major colorectal surgery.

Aged↗