Kirsten ras mutations in patients with colorectal cancer: the 'RASCAL II' study

Researchers worldwide with information about the Kirsten ras (Ki-ras) tumour genotype and outcome of patients with colorectal cancer were invited to provide that data in a schematized format for inclusion in a collaborative database called RASCAL (The Kirsten ras in-colorectal-cancer collaborative group). Our results from 2721 such patients have been presented previously and for the first time in any common cancer, showed conclusively that different gene mutations have different impacts on outcome, even when the mutations occur at the same site on the genome. To explore the effect of Ki-ras mutations at different stages of colorectal cancer, more patients were recruited to the database, which was reanalysed when information on 4268 patients from 42 centres in 21 countries had been entered. After predetermined exclusion criteria were applied, data on 3439 patients were entered into a multivariate analysis. This found that of the 12 possible mutations on codons 12 and 13 of Kirsten ras, only one mutation on codon 12, glycine to valine, found in 8.6% of all patients, had a statistically significant impact on failure-free survival (P = 0.004, HR 1.3) and overall survival (P = 0.008, HR 1.29). This mutation appeared to have a greater impact on outcome in Dukes' C cancers (failure-free survival, P = 0.008, HR 1.5; overall survival P = 0.02, HR 1.45) than in Dukes' B tumours (failure-free survival, P = 0.46, HR 1.12; overall survival P = 0.36, HR 1.15). Ki-ras mutations may occur early in the development of pre-cancerous adenomas in the colon and rectum. However, this collaborative study suggests that not only is the presence of a codon 12 glycine to valine mutation important for cancer progression but also that it may predispose to more aggressive biological behaviour in patients with advanced colorectal cancer.

Prognostic significance of TP53 gene mutation in 995 cases of colorectal carcinoma. Influence of tumour site, stage, adjuvant chemotherapy and type of mutation

Previous studies on the prognostic significance of TP53 gene alterations in colorectal cancer (CRC) have led to conflicting results. The present study investigated the prognostic significance of TP53 gene mutation in a very large series of 995 Dukes' B and C CRC patients, the majority of whom did not receive chemotherapy. Mutations were found in 385 (39%) cases and were not associated with tumour stage, histological grade, patient age or sex. Significantly more mutations were found in tumours from the left-sided colon compared with those from the right side (43% versus 34%, P=0.006). TP53 gene mutation had no prognostic value in the overall series or in different site or stage subgroups. None of the different types of TP53 gene mutation showed prognostic value. A trend for association with worse survival was observed in the patient subgroup that received adjuvant chemotherapy (Hazard Ratio (HR) 1.4, 95% confidence interval (CI) 0.89-2.21, P=0.15). These results indicate that mutation of the TP53 gene is not a useful prognostic marker for CRC patients who do not receive adjuvant chemotherapy. Further study is required to determine whether different types of TP53 mutation might be of value in predicting the response of CRC patients to chemotherapy.

Prostate tumours from an Asian population: examination of bax, bcl-2, p53 and ras and identification of bax as a prognostic marker

Molecular studies have suggested that ethnicity may play a significant role in prostate tumorigenesis, but no information exists for groups other than Caucasian or Japanese patients. We examined 62 archival samples of prostate tumours from Asians of non-Japanese origin for the over-expression of p53, for the possible presence of mutated ras genes, for the overexpression of the bcl-2 and bax proteins, as well as directly for the presence of apoptotic cells by the TUNEL methodology. Gene lesions of both ras (0%) and p53 (3%) were rare. While bcl-2 expression was not observed in any sample, bax expression was noted in 76% of samples and was associated with a significantly worse patient prognosis both overall (P< 0.005) and specifically in Chinese patients (P< 0.02). Apoptotic cells were found in 61% of samples, and were significantly associated with the presence of bax expression (P = 0.002), but not patient survival. These results suggest that prostate tumours from non-Japanese Asians are genetically distinct from prostate tumour found in both Japanese and Caucasian patients, and that treatment modalities may need to be tailored for specific population groups.

Apoptosis and apoptosis related gene expression in normal conjunctiva and pterygium

BACKGROUND

Pterygium is a relatively common eye disease in the tropics whose aetiology and pathogenesis remain uncertain. As such, interest has focused on understanding the underlying mechanism of pterygia development.

METHODS

15 specimens of pterygia from 15 eyes were examined, together with normal conjunctival tissue from the same eyes for the pattern of gene expression of genes associated with the induction or repression of apoptosis (p53, bcl-2, and bax). In addition, the samples directly for apoptotic cells were examined by the terminal deoxynucleotide transferase (TdT) mediated nick end labelling (TUNEL) methodology.

RESULTS

In pterygia specimens apoptotic cells were found mainly confined to the basal layer of cells of the epithelial layer, situated immediately adjacent to the fibrovascular support layer. These cells were shown to express significant levels of p53 and bax, as well as the apoptosis inhibiting protein bcl-2. In contrast, normal conjunctival specimens displayed no bcl-2 expression and apoptotic cells were seen throughout the entire width of the epithelial layer, coupled with high levels of bax expression.

CONCLUSION

These results support a model whereby pterygia development is a result of disruption of the normal process of apoptosis occurring in the conjunctiva.

HIT family genes: FHIT but not PKCI-1/HINT produces altered transcripts in colorectal cancer

Forty-five colorectal adenocarcinomas were examined for alterations in the HIT family genes FHIT and PKCI-1/HINT by a combination of reverse transcriptase polymerase chain reaction and DNA sequencing. In all cases a single transcript corresponding to the reported sequence was detected using primers specific for the PKCI-1/HINT gene. In contrast multiple transcripts were detected using primers specific for the FHIT gene transcript. 6% (3/45) of tumours evinced no detectable expression of any FHIT transcript and a further 12% (6/45) produced only the normal full length transcripts. Ninety-six aberrant transcripts were characterized from the remaining tumours. Deviations from the normal full length sequence characterized included deletions, insertions of novel sequences, a point mutation as well as the usage of a putative alternate splice site in exon 10. Message variants were detected with approximately equal frequency in all tumour stages with the exception that templates with insertions were found solely in Dukes' stage B tumours (P < 0.001). With the exception of the putative alternate splice site, aberrant transcripts were not detected in matched normal mucosa. These results suggest that members of the HIT family of genes are only selectively involved in tumorigenesis and that perturbation of FHIT gene expression is an early event in colorectal tumorigenesis.

c-Ki-ras mutations in colorectal adenocarcinomas from a country with a rapidly changing colorectal cancer incidence

We have examined the incidence of mutation of the c-Ki-ras proto-oncogene in colorectal adenocarcinomas from two different time periods, namely 1962-1966 and 1994-1996. The first cohort of samples consisted of formalin-fixed, archival paraffin block and represent the oldest colorectal cancer samples for which ras mutation has been examined, while the second cohort of tumours were fresh, flash-frozen samples representative of genetic events occurring in contemporary times. Analysis of mutation status was undertaken by a mismatch-specific oligonucleotide hybridization analysis of exon 1 of the c-Ki-ras proto-oncogene after amplification by the polymerase chain reaction. Mutations in codon 12 or 13 of c-Ki-ras were detected in 28% (14/50) of contemporary samples, a figure consistent with locally established mutation rates. In contrast no mutation was detected in any of the 18 samples from the earlier period, a result that is statistically significant (P = 0.007). Age-standardized rates of colorectal cancer in Singapore have seen a marked increase over the last 30 years, and for the first time we have shown that such an increase in colorectal cancer is associated, at least in part with an increase in incidence of a specific mutagenic change.

p53 point mutation and survival in colorectal cancer patients: effect of disease dissemination and tumour location

The relationship between p53 point mutation and patient survival was examined in 328 colorectal cancer patients. Point mutation was detected in 51% (166/328) of cases and was associated with a poorer prognosis in univariate and multivariate analysis. However, subcohort analysis showed that this relationship was restricted to patients with lymphatic dissemination, patients without evident distant metastatic lesions at the time of presentation and in tumours confined to the distal colorectum. These results suggest that the utility of p53 point mutation as a specific, patient based prognostic marker may be restricted to certain classes of patients.

Young Investigator's Award: induction of apoptosis following traumatic head injury in humans

Apoptosis or programmed cell death plays an important role in many developmental and pathological processes of the central nervous system. In head injury, apoptosis has been recently implicated in many studies on animal brain samples the phenomenon of apoptotic gene expression (bax and bcl-2). Twenty specimens of contused brain tissue (temporal and frontal lobe) from 20 patients who underwent emergency craniotomy and removal of mass lesions were obtained from May to October 1997. The samples collected were immediately snap frozen in liquid nitrogen and stored at -80 degrees C. Immunohistochemical analysis was performed to detect the expression of bcl-2, bax and p53 using standard avidin-biotin complex second antibody conjugate methodology utilising commercially available primary and secondary antibodies. The average age of cohort was 46.24 +/- 22.17 years, the average Glasgow Coma Scale on admission was 9.19 +/- 4.72, and the average duration from injury to collection of the sample was 20.62 +/- 40.57 hours. There was documented hypoxia and hypotension seen in 5 of the 20 patients (25%). Significant levels of bax protein expression were noted in all samples, and p53 expression in 30% of samples. No bcl-2 expression was observed. Our study showed that for the first time the strong expression of the pro-apoptotic gene (bax) and low levels of the anti-apoptotic gene (bcl-2), thus implicating the mechanism of apoptosis in brain injury following trauma. The use of agents to inhibit apoptosis may be beneficial in head injury patients.

Abnormal expression of the p53 tumor suppressor gene in the conjunctiva of patients with pterygium

PURPOSE

To determine whether pterygium is a disorder of abnormal growth by examining the expression of the p53 gene in the conjunctiva of patients with pterygium.

METHODS

Immunostaining for abnormal expression of p53 was performed using mouse monoclonal antibody to human p53, pAb 240, on six eyes with primary pterygium and two eyes with recurrent pterygium.

RESULTS

In three of the eight eyes with pterygium, specimens were positive for abnormal expression in the epithelium of the pterygium and in the superior bulbar conjunctiva.

CONCLUSION

Abnormal p53 expression in the epithelium of primary and recurrent pterygium specimens suggests that pterygium is a growth disorder rather than a degeneration.

CMV colitis masquerading as colon cancer--an unusual presentation of acquired immunodeficiency syndrome

We present a case-report of a patient with a typical history and a barium enema study diagnostic of right-sided colonic cancer. Laparotomy and right hemicolectomy was carried out. Histological examination revealed Cytomegalovirus (CMV) colitis and the patient was subsequently tested positive for Human immunodeficiency Virus (HIV). Gastrointestinal symptoms are common in patients with Acquired Immune Deficiency Syndrome (AIDS) and up to 10% of all AIDS patients have CMV colitis. The diagnostic criteria for CMV colitis is reviewed. AIDS is likely to become more common and we stress the awareness of this condition as well as the need for preoperative colonoscopy and histological diagnosis in patients with radiological diagnosis of colorectal carcinoma.

Surgery for inflammatory bowel disease in Singapore

Inflammatory bowel disease is uncommon in Asians and reports of surgery in these populations are rare. Eighty-two patients with inflammatory bowel disease were seen in the Department of Colorectal Surgery over a five-year period (1989-1994). Twenty-three patients underwent surgery for their disease. There were 12 males and 11 females with 16 Chinese, 4 Indians and 3 Malays. Twelve had Crohn's disease and 11, ulcerative colitis. The majority of patients with Crohn's disease had emergency surgery for bleeding, perforation, abdominal masses and intestinal fistulae. Fifty percent of these had the diagnosis made intraoperatively or post-operatively. Surgery for ulcerative colitis was indicated because of multiple relapses, non-response to medical treatment, side effects of therapy or malignant change. The median age at surgery of patients with Crohn's disease and ulcerative colitis was 39 years (range 24-84) and 40 (range 18-60) respectively. The median follow-up was 22.4 months (range 9-50). The results of surgical therapy in these patients show that surgery when indicated can be done with minimum morbidity and mortality.

Prognostic significance of p53 overexpression and mutation in colorectal adenocarcinomas

The p53 tumour-suppressor gene is found altered in the majority of colorectal cancers. Lesions include allelic loss, mutation of the gene and overexpression of the p53 protein. All of these lesions have been analysed for prognostic significance, and whereas both mutation and allelic loss have been shown to be reasonably useful markers of prognosis, the utility of overexpression of the p53 protein is more ambiguous. Given that many authors use p53 overexpression as a marker for point mutation this issue is of some importance. We have therefore examined 100 colorectal carcinomas for mutation of the p53 gene, as well as overexpression of the p53 protein. Results show that whereas mutation of the p53 gene is associated with p53 overexpression, the degree of association depends, at least in part, upon the particular antibody used. Moreover, although mutation of the p53 gene does provide prognostic information, overexpression of the p53 protein, as detected with two antibodies, does not. These results suggest that immunohistochemistry is not a suitable alternative to direct detection of mutation in assessing prognosis in colorectal cancer patients.

The investigation of chronic constipation for surgical management

AIMS

This study was conducted to ascertain the incidence of patients requiring surgery for intractible constipation. We also aimed to determine the anorectal physiology findings which influenced the surgery, and the outcome of surgical intervention.

METHODS

A prospective study was done on 217 patients (34 men, 183 women; mean age 59 years [SD 17.7]) managed in a tertiary referral centre. Physiological tests consisting of transit marker studies, anal manometry, electromyography (EMG) and synchronised mano-myo-cinedefaecography (SMC), were then performed where appropriate. Surgical management was based on the results of these investigations. The mean follow-up was 19.6 months (SD 9.3).

RESULTS

Eighteen patients (8.3 percent) underwent surgery: 2 for Hirschsprung's disease, 8 for colonic inertia (CI) and 8 for obstructed defaecation (OD). CI patients were younger than the OD patients (p = 0.03). Transit marker studies were abnormal but manometry was not different from the OD patients. The latter were identified on SMC to have rectoceles, sigmoidocele or rectal intussusception. The stool frequency significantly improved after surgery (before = 1.9 bowel motions a week [SD 0.9], after = 8.8 bowel motions a week [SD 1.2]; p = 0.003). There were no complications.

CONCLUSIONS

A small but significant proportion of constipation patients require surgery. Good results are obtainable when surgery is directed by the findings of anorectal physiology investigations.

Overexpression of the c-myc proto-oncogene in colorectal carcinoma is associated with a reduced mortality that is abrogated by point mutation of the p53 tumor suppressor gene

The survival of 119 colorectal cancer patients was analyzed in the light of the overexpression status of the c-myc proto-oncogene mRNA and the point mutation status of the p53 tumor suppressor gene in the primary adenocarcinoma. The presence of >3 fold overexpression of c-myc mRNA in the primary tumor was found to be associated with a better prognosis than patients who evinced no overexpression (P = 0.02, log rank analysis). Point mutation of the p53 tumor suppressor gene was found to be associated with a poorer patient prognosis (P = 0.007, log rank analysis). Endogenous levels of c-myc and point mutation of p53 both contributed independently toward a poorer patient prognosis in Cox regression modeling. The better prognosis seen in patients who overexpress c-myc was offset when c-myc overexpression was coupled with a point mutated p53 gene. These results suggest that in colorectal adenocarcinoma c-myc deregulation leads to increased apoptotic death, but that this response may be modulated by a more downstream event such as point mutation of the p53 gene.

Clinical and physiologic effects of biofeedback in outlet obstruction constipation

PURPOSE

We report the results of biofeedback (BF) on patients with outlet obstruction defecation (OOC), including those with and without measurable paradoxical puborectalis contractions (PP). Clinical and anorectal physiologic parameters (ARP) were assessed one week before and after a standardized course of BF.

METHODS

Sixty-two consecutive patients (24 men, 38 women; mean age, 48 (standard error of the mean, 2.3) years) were recruited. All had persistent constipation despite six weeks of dietary fiber supplements. Colonic inertia was excluded by transit marker studies. Defecating proctography excluded anatomic abnormalities causing outlet obstruction. Patients underwent four outpatient sessions of biofeedback, each session lasting one hour.

RESULTS

After BF, 56 patients (90.3 percent) were subjectively improved. Frequency of spontaneous bowel movements were significantly increased (P = 0.003). Frequency of laxative-induced (P = 0.004) and enema-induced (P = 0.005) stools were reduced. Anal resting (P = 0.04) and squeeze (P = 0.002) pressures were increased. Number of patients with PP was reduced from 40 to 31 (P = 0.004). Presence of PP did not affect response to BF. There were no differences in ARP between the 56 patients who improved and the 6 who did not. There were no side effects or clinical regressions after a mean follow-up of 14.9 (standard error of the means, 0.9) months.

CONCLUSIONS

BF effectively treated OOC in 90.3 percent, regardless of PP. Anal pressures were increased, and PP was decreased.

C-KI-RAS activation and the biological behaviour of proximal and distal colonic adenocarcinomas

One hundred and forty colonic adenocarcinomas originating on the left side of the colorectum and 70 colorectal carcinomas originating on right side of the colorectum were examined for activating mutations of codons 12 and 13 of the C-KI-RAS proto-oncogene. Rates of mutation were significantly different (right colon 43%, 30/70 versus left colon 23%, 32/140; P = 0.0025). Adenocarcinomas from the left side of the colorectum showed a significant association between C-KI-RAS activation and tumour progression, including the presence of distant organ metastasis at the time of surgery (P = 0.0039), and during patient follow-up (P = 0.00027), whereas those from the right of the colorectum did not (P = 0.4 and P = 0.5, respectively). Mutation of the C-KI-RAS proto-oncogene was found to be associated with a significantly poorer patient prognosis on the left of the colorectum (P = 0.0001 by log rank analysis of Kaplan-Meier plots) but not on the right (P = 0.7). These results demonstrate that, not only is the timing and frequency of C-KI-RAS activation different between carcinomas originating on the left or right of the colorectum, but also that the biological consequences of such mutations may differ.

Bowel function survey after segmental colorectal resections

PURPOSE

Long-term bowel function after right hemicolectomy (RHC), extended right hemicolectomy (ERHC), left hemicolectomy (LHC), sigmoid colectomy (SC), and anterior resection (AR) was evaluated.

METHOD

Three hundred fifteen patients (52.3 percent) replied to a questionnaire on stool frequency, fecal continence, and defecation problems. All patients had undergone surgery at least one year before questionnaire was sent to them. Patients with anastomotic leaks and recurrences were excluded.

RESULTS

Stool frequency was one to two bowel movements per day in 78 percent of patients after RHC, 75 percent after ERHC, 57.6 percent after LHC, 64.3 percent after SC, and only 44.8 percent after AR (P = 0.01). Continence affected lifestyle in 32 percent of patients after AR, but affected only up to 11.5 percent of patients who had had more proximal resections (P = 0.001). Defecation problems occurred in less than 15.4 percent after RHC, ERHC, and LHC but were encountered more frequently after SC (25 percent) and AR (28.4 percent; P = 0.009).

CONCLUSIONS

Problems with postoperative bowel function were appreciably more common after SC and AR.

p53 and prognosis in colorectal cancer

The p53 tumour suppressor gene is found altered in the majority of colorectal adenocarcinomas. While these changes are believed to reflect underlying mechanisms of tumour development and progression, it is becoming increasingly clear that such changes may also reflect the macroscopic biological behaviour of the course of the disease. Knowledge of the p53 tumour suppressor gene status may therefore provide important prognostic information. This review examines some of the data that are beginning to show that p53 tumour suppressor gene status may be an important prognostic indicator.

Molecular changes of colorectal cancer in Singapore

Improved success in the management of colorectal cancer requires a better understanding of its development and biological behaviour. The key for this is molecular genetics. Gene changes parallel the multi-step changes in the adenoma-carcinoma sequence. Cancer results from a variable combination of defects in oncogenes, tumour suppressor, mutator and apoptotic genes. These changes are similar whether they occur in inherited disorders like adenomatous polyposis coli (APC) and hereditary non-polyposis colorectal cancer (HNPCC) or acquired cancer in the elderly. In Singapore, the c-myc and c-Ki-ras proto-oncogenes are found to be activated in 70% and 29% of tumours respectively. Allelic loss of chromosome 5q and 17p occurs in 25% and 70% of tumours respectively, while point mutation of the p53 tumour suppressor gene occurs in 50% of colorectal cancers. Both the frequency and the nature of the lesion occurring are compatible to the changes detected in Caucasian patients, suggesting common aetiological factors. The biological behaviour of colorectal adenocarcinomas is determined by the nature of defects or mutations in key genes such as the p53 tumour suppressor gene. Lymphatic spread is associated with the presence of point mutations and haematogenous spread is associated with loss of heterozygosity of p53. Survival is worse when conserved regions of the gene are mutated compared with those outside, and worst when codon 175 is mutated. Sensitivity to radiotherapy and chemotherapy is also determined by p53 mutation which controls apoptosis. Prognosis could now be individualised and with the prospect of gene therapy, molecular genetics will have a major impact on the management of colorectal cancer.

Use of molecular methods in the early diagnosis of familial adenomatous polyposis and hereditary nonpolyposis colorectal cancer

Familial adenomatous polyposis (FAP) and hereditary nonpolyposis colorectal cancer (HNPCC) are the most well-defined heritable conditions which predispose to colorectal cancer at a young age. Significant progress in understanding the pathogenesis of FAP and HNPCC has led to the development of techniques which can be used for the diagnosis of these two conditions. In this article, the technical aspects and clinical applications of molecular methods such as linkage analysis, mutational analysis and in vitro synthesised-protein assay for FAP and microsatellite instability or replication error (RER) assay for HNPCC are described and discussed. The potential of such molecular tests is the identification of affected individuals for proper surveillance and management as well as the identification of non-affected individuals to free them from the trauma of uncertainty and repeated unnecessary colonoscopies.

p53 point mutation and survival in colorectal cancer patients

We have examined the relationship between point mutation of the p53 tumor suppressor gene and survival in colorectal cancer patients. We found that patients with tumors harboring mutated p53 genes showed a significantly poorer prognosis than did those patients with genes without point mutations, and, moreover, patient response to postoperative therapies depended significantly on mutation status in both adjuvant and palliative treatment cohorts. However, not all point mutations were the same functionally; point mutations within the conserved domains of the p53 tumor suppressor gene were inherently more aggressive than tumors with point mutations outside of these domains, and mutations of codon 175 were particularly aggressive. These results suggest that knowledge of a patient's p53 status, both with respect to the presence of point mutations and to the specific nature of the lesion, may be required to accurately predict both the course of the disease and the response of the disease to postoperative therapeutic interventions, especially those therapies based on the induction of apoptosis in the neoplastic cell.

The presymptomatic molecular diagnosis of familial adenomatous polyposis in Singapore

Familial adenomatous polyposis (FAP) is an autosomal dominant disorder which predisposes to the development of colorectal cancer. The adenomatous polyposis coli (APC) gene, mutation of which is responsible for FAP, has been localised to chromosome 5q21. Linkage studies using DNA markers have proven useful for presymptomatic diagnosis of at-risk individuals. We have examined 8 FAP families from the Singapore Polyposis Registry by using 4 linked and 2 intragenic DNA markers. Presymptomatic diagnosis could be made in 84% (37 of 44) of at-risk individuals. Among these presymptomatically diagnosed cases, positive prediction was made in 32% (12 of 37) whereas negative prediction was possible in 68% (25 of 37). As the accuracy of genetic diagnosis is high and the test reliable in most cases, the major impact of these tests will be the reduction of unnecessary anxiety and a significant reduction in the frequency of screening for at-risk individuals who are not carrying the affected gene.

Bladder involvement in patients with colorectal carcinoma

Twenty-seven patients underwent concomitant partial cystectomies out of a total of 542 patients with colorectal carcinoma operated on between October 1989 to December 1991. There were 19 males and 8 females with a median age of 63.7 years (range 44-80). The patients were followed up for a median of 40.2 months (range 27-75 months). Histological invasion into the bladder was found in only 26% of the tumours. Eighty-five percent of the patients with carcinomatous invasion had preoperative urological symptoms whilst only 20% of those with inflammatory adhesions had urological symptoms. Four percent of the patient were Dukes' A, 50% Dukes' B, 42% Dukes' C and 4% Dukes' D. Twenty (74%) patients are alive without evidence of local or distant metastasis. One has local recurrence and another, distant metastasis. Five patients have died. The prognosis of patients with colorectal cancer and bladder involvement appears to be similar to those without bladder involvement provided clear margins are obtained.

Prospective randomized controlled trial of a micronized flavonidic fraction to reduce bleeding after haemorrhoidectomy

A prospective randomized controlled trial was carried out on the effects of Daflon 500 mg (a micronized flavonidic fraction containing diosmin 450 mg and hesperidin 50 mg) on bleeding after haemorrhoidectomy. In all, 228 consecutive patients with prolapsed irreducible piles were recruited. Elective haemorrhoidectomy was performed with a standardized diathermy excision method. Some 114 patients were randomized to receive Daflon 500 mg for 1 week after operation (group 1), and there were 114 controls (group 2). Postoperative analgesia and laxative prescription as well as hospital stay were otherwise the same. One patient (0.9 per cent) from group 1 and seven (6.1 per cent) from group 2 had postoperative bleeding (P = 0.03). All bleeding occurred from 6 to 15 days after haemorrhoidectomy. There were no side-effects from the use of Daflon 500 mg. The risk of secondary bleeding from haemorrhoidectomy is reduced with postoperative Daflon.

Increased mRNA expression of the receptor-like protein tyrosine phosphatase alpha in late stage colon carcinomas

The protein tyrosine phosphatase alpha (PTP alpha) mRNA level in paired samples of late stage (Dukes' D) colorectal tumors and adjacent normal colon mucosa was quantified by RNase protection assays. After normalization against 18S RNA or beta-actin mRNA level, a 2-10-fold increase in PTP alpha mRNA was detected in 10 of 14 tumors (approximately 70%) compared to mucosa. In situ hybridization of digoxigenin-labelled antisense PTP alpha RNA to tumor and mucosa sections produced a signal only in neoplastic cells of the tumor sample, consistent with the high increase in PTP alpha mRNA detected by RNase protection assays of some of the tumors. This is the first report suggesting an association of a protein tyrosine phosphatase with colorectal carcinoma. PTP alpha is a receptor-like PTP thought to be involved in regulating cell proliferation. Its oncogenic properties when overexpressed in cultured fibroblasts suggest that PTP alpha overexpression could contribute to the tumorigenic process in colon carcinoma.

Colorectal cancer in the young adult

Out of 964 patients presenting with primary colorectal cancer (CRC) to the Department of Colorectal Surgery, Singapore General Hospital between April 1989 until December 1992, there were 57 (5.9%) aged 40 years or less. These younger patients were significantly more likely to have a family history of cancer, particularly CRC; a tumour situated more proximally; and tumours displaying certain characteristics histopathologic features. There were no adverse findings for clinicopathologic staging at presentation, curative resection rate, and systemic recurrence rate within the early follow up period. With proper management, the young adult with CRC enjoys the same outlook as his older counterpart. But, in view of the likely operation of inherited genetic factors, follow up surveillance of the patient and the provision of advice and screening are vital elements in optimising outcome. Furthermore, advice and screening should be available for first degree relatives as well.

Prospective randomized trial comparing J colonic pouch-anal anastomosis and straight coloanal reconstruction

Twenty patients (13 men) with low rectal cancer, median (range) age 64.5 (38-83) years were prospectively randomized to undergo ultra-low anterior resection with a J colonic pouch-anal anastomosis (median (range) distance of anastomosis from the anal verge 3 (1-4) cm). Another 20 patients (15 men), median (range) age 62.5 (44-86) years) with low rectal cancer were randomized to a straight coloanal anastomosis (median (range) distance of anastomosis from the anal verge 3.25 (2-5) cm). There were no significant differences in operative time or complications between the two groups. There was significantly better postoperative anal function in patients who underwent pouch-anal anastomosis at 1, 6 and 12 months after ileostomy closure. At 12 months all patients (19 of 19) with a pouch reconstruction had regained normal continence compared with 14 of 20 of those who had a straight coloanal anastomosis. No patient complained of severe constipation requiring enema or intubation to evacuate.

Comparison study of DNA content of primary and metastatic lymph node lesions of colorectal cancer

Abnormal DNA content or aneuploidy in cells usually indicates malignancy. In colorectal cancer aneuploidy has been shown to confer a poorer prognosis suggesting that aneuploid cancers are more aggressive. The mechanisms involved in the aggressive behaviour of an aneuploid tumour are still unknown. The aim of this study was to compare the patterns of aneuploidy of colorectal cancers and that of their corresponding lymph node metastases and to relate them to clinical outcomes. One hundred and one patients were studied, 81 (Dukes C) with lymph node metastasis only and 20 (Dukes D) with obvious distant metastasis as well. Forty-six (46.5%) of the tumours and an equal number of the lymph nodes were found to be aneuploid. Twenty-eight (60.9%) of the aneuploid tumours showed aneuploid metastasis and 18 (39.1%) showed diploid metastasis. Similarly, 37 (67.3%) of the diploid tumours showed diploid metastasis whereas 18 (32.7%) showed aneuploid metastasis. Local recurrence and distant metastasis were compared among the aneuploid and diploid primary tumours. Although there was no statistically significant difference, distant metastasis was more common in aneuploid tumour. Ploidy of the lymph node was not related to local recurrence or distant metastasis. We conclude that DNA ploidy by itself does not determine the metastatic potential of the tumour cell and that in about 50% of the tumours, the lymph node metastasis consists of clones of cells different from the primary tumours. We also conclude that the clinical outcome of the disease in terms of recurrence and metastasis cannot be predicted by the ploidy of the lymph node metastatic lesions.

Allelic loss of the p53 gene in colorectal cancer

The loss of specific chromosomal loci in cancers is indicative that the region contains a tumour suppressor gene. Allelic loss of chromosome 17p has been shown to occur in a wide variety of cancers such as lung, breast, colon, ovary and brain and, until recently, the gene believed to be involved was the p53 tumour suppressor gene. However, more recent studies have shown that the area deleted in some of these tumours does not include the structural gene for p53. For this reason it has been proposed that a tumour suppressor gene lying distal to p53 on chromosome 17p is the gene deleted in these cancers. As chromosome 17p has been shown to be deleted in approximately 75% of colorectal cancers, we set out to determine whether the target gene of these deletions was the structural gene for p53. Allelic loss was assessed by using restriction fragment length polymorphisms in 52 tumours. Deletions distal to p53 on chromosome 17p were assessed using the probe YNZ22.1 and allelic loss of p53 was assessed using probe pR4-2, a cDNA probe specific for the p53 gene. Out of the 21 tumours informative for both probes, 3 cases showed no allelic deletion of the chromosome 17p, 2 cases showed allelic deletion not encompassing the p53 gene and 16 cases (89%) showed allelic deletion including the p53 gene.(ABSTRACT TRUNCATED AT 250 WORDS)

Ileostomy output in the early postoperative period

The high volume output of a defunctioning loop ileostomy after rectal excision and anastomosis may lead to severe dehydration and electrolyte imbalance if not properly managed. Although chronic losses may be seen, the early postoperative period remains the most hazardous with regard to acute fluid and electrolyte losses for the patient with a defunctioning ileostomy1–3. A prospective study was therefore conducted to determine the period and severity of excessive ileostomy loss.

Association of activated proto-oncogenes ras and myc in colorectal carcinomas

We have examined 60 colorectal carcinomas for activation of two proto-oncogenes, c-myc and c-Ki-ras. Over-expression of c-myc mRNA as determined by Northern analysis was found in 58% of cases (35/60). Activation of the c-Ki-ras gene by point mutations in codons 12 or 13 as determined by mismatch specific oligonucleotide hybridisation was found in 35% (21/60) of cases. There was a statistically significant association between activation of c-Ki-ras and over-expression of c-myc (P = 0.03), with 76% of tumours with an activated c-Ki-ras proto-oncogene showing over-expression of c-myc. The association was significant in left-sided colorectal tumours (P = 0.03) but not right-sided (P = 0.5). However, whereas only 59% of left side tumours showed at least one of the two changes (ras activation only, or myc activation only or both), 93% of right side tumours showed at least one of the changes (P = 0.01). Twenty-two percent of left side tumours showed both changes compared with 35% of right side tumours, although this result did not achieve significance (P = 0.2). These results suggest that in left-sided colorectal tumours ras and myc cooperate, as established in vitro, to produce neoplastic transformation while different pathway(s) are involved in right-sided tumours.

Anorectal physiological parameters in chronic constipation of unknown aetiology (primary) and of cerebrovascular accidents--a preliminary report

Chronic constipation may be secondary to dietary, metabolic or neurological causes such as cerebrovascular accidents (CVA). In certain patients, the cause is unknown (primary idiopathic constipation [PIC]). This study compared the anorectal physiological parameters of 15 PIC patients (all females; median age 40, range 32-48 years) with 7 CVA patients (M:F = 6:1; median age 58, range 51-67 years), to observe the influence of cerebral factors on the anorectal physiology of constipation. Twenty-five normal subjects (M:F = 13:12; median age 47, range 43-50 years) acted as controls. Transit marker studies showed decreased passage in both groups, but 9 of the PIC patients had a diffuse pattern (slow transit constipation [STC]) and 6 had a pelvic outlet obstruction pattern (PO). The CVA patients had a diffuse pattern of delayed transit. Rectal sensation was significantly impaired in STC (P < 0.05) but not in PO or CVA. Electromyographic evidence of paradoxical puborectalis contractions was significantly more common in PO only (P < 0.05). Therefore, CVA patients had a different anorectal physiological pattern of constipation from PIC patients.

Haemorrhoidectomy and disordered rectal and anal physiology in patients with prolapsed haemorrhoids

The effect of haemorrhoidectomy on rectal and anal physiological abnormalities was studied in 24 consecutive patients (12 men and 12 women of mean (s.e.m.) age 39.1 (2.4) years) and compared with results in 13 sex- and age-matched controls. Before operation those with haemorrhoids had significantly higher resting anal pressures (P < 0.005), lower rectal compliance (P < 0.05) and more perineal descent (P < 0.05). Following haemorrhoidectomy there were significant decreases in the maximum resting (P < 0.05) and maximum squeeze anal (P < 0.001) pressures to within normal values 3 months after operation. Rectal compliance also increased significantly (P < 0.05), to that of normal controls. The abnormalities found in patients with prolapsed piles reverted to the normal range within 3 months of haemorrhoidectomy. These physiological changes are therefore more likely to be an effect, rather than the cause, of enlarged anal cushions.

Unilateral anal electrosensation. Modified technique to improve quantification of anal sensory loss

PURPOSE

Anal electrosensation is usually tested by an annular configured electrode that stimulates the circumference of the anus. In certain pelvic conditions, the right and left pudendal nerve function may be damaged separately and to different degrees. This may only be detected by a unilateral electrode testing each side independently.

METHODS

Our study compares accuracy and sensitivity of annular and unilateral electrodes in assessing patients with hemorrhoids, perineal descent, incontinence, after low anterior resection, and constipation (107 subjects).

RESULTS

In normal controls (n = 19), annular thresholds ranged from 0.5 to 2.7 mA and unilateral thresholds from 0.6 to 2.6 mA. In prolapsed hemorrhoids, unilateral was more sensitive than annular electrode in detecting deficits at the upper (P < 0.0001), mid (P < 0.005), and lower (P < 0.0005) anus. Patients with perineal descent had a sensory deficit in the upper anal canal, detected more consistently by unilateral electrode (P > 0.05). No significant abnormalities were found in neuropathic incontinence, after anterior resection and chronic constipation. Results of the unilateral electrosensory technique were found to be consistent with repeated measurements (r = 0.8878; P < 0.001).

CONCLUSIONS

By being more sensitive than the annular technique, the unilateral electrode method may become, with refinement, a useful test for quantifying anal sensation.

Anal stricture following haemorrhoidectomy: early diagnosis and treatment

Anal stricture is an uncommon but well recognized complication following haemorrhoidectomy. Twenty-seven (3.8%) out of 704 (500 elective and 204 emergency) cases of haemorrhoidectomy performed at the Singapore General Hospital over a 24 month period had clinical evidence of anal stricture post-haemorrhoidectomy. Of the 27 cases, 15 had haemorrhoidectomy as an elective procedure while 12 had it performed as an emergency procedure (chi 2 = 3.26, 1 d.f., P > 0.05, not significant). The mean interval between surgery and presentation of anal stricture was 6 weeks (range 3-12 weeks). Eighteen of the patients were managed by anal dilatation in the outpatient clinic combined with bulk laxatives and a local anaesthetic agent. The other nine patients required a minor surgical procedure comprising either a lateral internal sphincterotomy (five) or an anoplasty (four) procedure. All patients were well, following treatment. None of these patients developed a recurrent stricture at follow up 3 months after treatment. It was concluded that although anal stricture following haemorrhoidectomy is rare, it should be detected and treated early in order to avoid pain and suffering, and treatment is usually successful.

Solitary rectal ulcer syndrome: the clinical entity and anorectal physiological findings in Singapore

The clinical pattern and physiological abnormalities in solitary rectal ulcer syndrome (SRUS) occurring in Singapore, were investigated. Since April 1989, 25 patients have presented with histologically proven SRUS. There were 13 males and 12 females (20 Chinese, 4 Malay and 1 Indian) with a mean age of 47.5 (+/- 3.1) years. Ninety-six per cent presented with rectal bleeding, 92% strained at stools, 40% had mucus discharge, 40% felt incomplete defecation and 32% digitated to defecate. Four had previous haemorrhoidectomies that did not cure their symptoms. The lesions were at a mean 6.8 (+/- 0.5) cm above the anal verge, usually anteriorly (64%) but one was circumferential. Anorectal physiology performed on 14 patients was compared with 13 age and gender matched normal controls. The measured mean resting perineum level in SRUS (1.4 +/- 0.3 cm) was significantly lower than in normals (P < 0.01). The mean anal electrosensory threshold (2.5 +/- 0.52 mV) was also significantly higher than in the controls (P < 0.05). Fifteen patients were successfully treated with a high fibre diet and avoidance of straining. Three patients required surgery and the most recent seven patients have responded well to biofeedback treatment. Awareness of this uncommon anorectal condition is necessary for early diagnosis and appropriate management. The physiological findings support a pelvic straining pathophysiology resulting in perineal descent, with less sensitive rectal mucosa prolapsing into, and raising, the anal canal electrosensory threshold. Treatment strategies aimed at correcting the straining have usually been successful.

The neurophysiological significance of perineal descent

The establishment of a linear relationship between perineal descent (PD) and pudendal nerve motor terminal latency (PNMTL) is important in understanding the pathophysiology of pudendal neuropathy. The amount of stretching of the pudendal nerve resulting from the extent of PD, should correlate with the amount of injury sustained (PNMTL). The two key previous studies which used different techniques to measure PD, have differed on this vital issue. A prospective study was undertaken in 141 consecutive patients with PD (M:F = 57:84; mean age 46.3 SEM 1.6 years) to clarify this discrepancy. The patients had chronic constipation (81), neurogenic faecal incontinence (31), rectal mucosal prolapse (17) or female urinary stress incontinence (9). All underwent measurements of PD (by perineometry), anal sphincter pressures, single fibre anal sphincter electromyography and PNMTL. These variables, as well as age were analyzed for a linear relationship with PD by multiple regression analysis. Age was the only independent variable predicting PD at rest (T = -3.2; p < 0.005). PNMTL was the only independent variable predicting PD on straining (T = -3.0; p < 0.005). In conclusion, a linear relationship between PD on straining and PNMTL was confirmed, supporting the previous study which also measured PD by perineometry. The other study which refuted such a relationship measured PD radiologically, and it is likely that the difference was in the measurement technique.

A detailed study of p53 mutations in colorectal cancer in Singapore

The p53 tumour suppressor gene plays a pivotal role in colorectal cancer formation. Understanding the mechanisms by which p53 is altered in tumour cells could lead to a better understanding of this common cancer. Unfortunately, there is no published information on Chinese patients. We have therefore conducted a series of studies on the p53 tumour suppressor gene in Singaporean colorectal cancer patients and have since demonstrated that 69% of patients have lost one copy of the p53 gene by allelic deletion of chromosome 17p, 55% of patients have a point mutation in one copy of the p53 gene, and that these changes are associated with tumour site, DNA aneuploidy and the pattern of disease dissemination. We present here a further study conducted on the specific nature and frequency of p53 mutations. DNA sequence analysis of 38 tumours from Chinese colorectal cancer patients with p53 mutations showed that 97% (37/38) of the mutations consisted of base substitutions, leading to the incorporation of alternate amino-acids in the p53 protein. The remaining mutation consisted of a single base insertion leading to the generation of a stop-codon, leading to the truncation of the protein some 14 amino-acids downstream from the site of the mutation. Sixty-eight percent of the mutants consisted of guanine to adenine (G-->A) transitions and 58% occurred at CpG dinucleotides. Eighty-seven percent of all mutations occurred at evolutionarily highly conserved regions, with 50% of mutations occurring in codons 175, 248 and 282.(ABSTRACT TRUNCATED AT 250 WORDS)

Role of cell kinetics from rectal scrapings in predicting risk of colorectal cancer

It has been suggested that cells obtained from scrapings of rectal mucosa can be readily analysed by flow cytometry for DNA content. Aneuploidy, if detected in these cells, will indicate a field change in the rectal mucosa. If so, this could provide a convenient means of selective screening for colorectal cancer. Rectal scrapings were obtained and analysed from 90 patients (23 patients with cancer, 13 patients in whom the cancer had been resected, 21 patients with benign adenoma and 33 patients with normal colorectum). Only 1 normal patient, 3 cancer patients and 1 resected patient showed aneuploidy, the rest were diploid. S-phase analysis showed the highest S-phase (18.0%) in the adenoma group and lowest (12.7%) in the normal group. The difference was not statistically significant (P = 0.06). S-phase was significantly higher among normal males (16.3%) than normal females (9.2%) (P = 0.008). In the adenoma group, however, the females showed a slightly higher S-phase (18.4%) than the males (17.8%), suggesting that S-phase measurement may be important in the study of carcinogenesis. In conclusion, aneuploidy in cells obtained from rectal scrapings is not a useful marker for increased risk of colorectal cancer as it was found in only 13% of the cancer patients. S-phase studies show more promise and need to be more extensively studied.

Performing internal sphincterotomy with other anorectal procedures

PURPOSE

A study was conducted to compare the outcome of combined anorectal procedures involving lateral internal sphincterotomy with lateral internal sphincterotomy alone to determine if the former results in increased complications.

METHODS

Complications and anal function of 57 patients who underwent lateral internal sphincterotomy for chronic anal fissure in conjunction with another anorectal procedure (combined group) between April 1989 and June 1992 were compared with 57 other age- and sex-matched patients who underwent lateral internal sphincterotomy alone (control group).

RESULTS

There was no statistical difference in the incidence of incontinence in the combined group (8.7 percent) and the control group (7 percent). None of the cases in either group had permanent incontinence. There were also no statistical differences in the incidence of postoperative bleeding, pruritus ani, mucus discharge, abscess formation, fistulation, and rates of fissure recurrence.

CONCLUSIONS

Additional anorectal procedures performed at the same time as internal sphincterotomy do not increase the incidence of postoperative complications.

Small bowel causes of per rectum haemorrhage

The majority of cases of per rectal haemorrhage (PRH) are due to colorectal causes within the diagnostic reach of the colonoscope. However a few cases are from the small bowel which may pose difficulty and delay in diagnosis. We reviewed 1489 patients with PRH from 1989 to 1993 and identified 10 cases of bleeding originating from the small bowel (0.7%). These were diagnosed when both the colonoscopy and upper gastrointestinal endoscopy were negative or by observing blood coming through the ileo-caecal valve. The causes were Meckel's diverticulum (4), leiomyoma (1), intussusception (1), lymphoma (1), carcinoma (1), Crohn's disease (1) and vasculitis (1). Six cases presented with active bleeding and haemodynamic instability; 4 had chronic bleeding associated with anaemia. Bleeding from Meckel's diverticulum could be differentiated by age, mid-20s or younger compared with mid-40s or older of non-Meckel's cases. Small bowel causes need to be considered in PR bleeding unexplained on colonoscopy and oesophagogastroduodenoscopy findings. A 99mtechnetium isotope scan is most likely to be of help in the young adult but from mid-life onwards, however, other techniques such as small bowel barium studies are required.

Rectal carcinoma during pregnancy

Rectal carcinoma presenting during pregnancy is rare with a reported incidence of 0.002%. Management of such an emotionally charged condition can be difficult, especially when the twin goals of curing the disease and preserving the pregnancy are divergent. Four cases of rectal carcinoma presenting during pregnancy are reported. In the first or second trimester of pregnancy, it is possible to resect the tumour with preservation of pregnancy, and in the third trimester, it is best to bring the pregnancy to term before removing the tumour. Unfortunately, the prognosis for such rectal cancer is poor.

p53 and behaviour of colorectal cancer

The tumour suppressor gene p53 is altered in most colorectal tumours. We found that lymphatic dissemination was driven by the presence of mutated p53 whether or not the cell contained wild-type p53. In a total sample of 187 specimens, point mutation of the p53 gene occurred in 70% and 43% of cases with and without lymph-node involvement, respectively. By contrast, haematogenous dissemination was apparently the result of absent functional wild-type p53 (whether or not the cell contained mutated p53). These results are of potential importance in the prediction of the clinical behaviour of a tumour.

Caecal mass on barium enema study--a case for routine colonoscopy

Prolapse of the ileal mucosa through the ileo-caecal valve or minor ileo-caecal intussuception is not uncommon and may occasionally be mistaken radiologically for a caecal neoplasm, especially if intestinal obstruction, abdominal pain or rectal bleeding is present. Colonoscopic visualisation and biopsy is important before surgery is advised. We describe a case of ileal mucosa prolapse masquerading as a caecal neoplasm on barium enema study. Colonoscopy showed prolapse of the ileal mucosa which was easily reduced by air insufflation and therefore unnecessary surgery was avoided.

Comparison of emergency and elective haemorrhoidectomy

A total of 704 patients with symptomatic prolapsed haemorrhoids were operated on over a 24-month period. Overall, 500 underwent elective haemorrhoidectomy for symptomatic prolapsed haemorrhoids and 204 emergency haemorrhoidectomy for acutely prolapsed, thrombosed or gangrenous haemorrhoids. The mean age was 43 (range 16-80) years in patients undergoing elective surgery and 42 (range 20-86) years in those receiving emergency procedures. After elective surgery 27 patients (5.4 per cent) had an episode of secondary haemorrhage; ten (2.0 per cent) required blood transfusion and six (1.2 per cent) needed surgical haemostasis. After emergency surgery, ten patients (4.9 per cent) developed secondary haemorrhage; four (2.0 per cent) required blood transfusion and two (1.0 per cent) surgical haemostasis. Twelve patients (5.9 per cent) developed anal stenosis after an emergency procedure compared with 15 (3.0 per cent) after elective operation. None of the patients in either group developed portal pyaemia. After elective surgery 26 patients (5.2 per cent) developed a degree of incontinence (eight to flatus, 15 to liquids, three to solids) as did nine patients (4.4 per cent) after emergency procedures (three to flatus, five to liquids, one to solids). Recurrent haemorrhoids were found in 38 patients (7.6 per cent) after elective surgery and in 14 (6.9 per cent) after an emergency procedure.

Unusual rectal perforation--an individualised approach to management

The management of rectal perforations is controversial. Surgical repair or resection and anastomosis is usually undertaken with faecal diversion in the management of traumatic perforations. Primary repair without colostomy is less commonly employed. Five cases of rectal perforation seen in the Department of Colorectal Surgery, three from penetrating foreign objects and two from barium enema examination, are presented. The principles of management of patients with rectal perforations include faecal diversion, primary repair of rectal perforation and sphincter muscles, presacral drainage, parenteral antibiotics and distal bowel irrigation. This approach was used in the management of these five cases and the results were very satisfying.

The laparoscope: an excellent illumination tool for deep pelvic dissection

Adequate illumination during deep pelvic dissection in low anterior resection and abdominoperineal resection is sometimes difficult and frustrating, especially in deep narrow pelvises. Various methods of illumination are being used to overcome this problem. We present our technique of using the laparoscope as an excellent illumination tool for deep pelvic dissection in conventional surgery.

The ileo-anal reservoir: results from an evolving use of stapling devices

Thirteen patients had a hand-sewn pouch-anal anastomosis (group A) during restorative proctocolectomy for familial adenomatous polyposis. Median length of follow-up since ileostomy closure was 41.5 months (range 30-56 months). Median stool frequency per 24 h was 4.5 (range 2-5). Six patients were fully continent, three were incontinent to flatus and three patients were occasionally incontinent to liquid stool. Three patients suffered nocturnal seepage but all patients could defer the urge to defaecate by at least 15 min. Fourteen patients (familial adenomatous polyposis: seven; ulcerative colitis: six; intractable constipation: one), had a totally stapled ileal J pouch and pouch-anal anastomosis (group B). Five patients did not have a defunctioning ileostomy while nine patients did. Median follow-up after ileostomy closure or one-stage restorative proctocolectomy was 17.5 months (range 1-30 months). Median frequency of bowel movement per 24 h was 4 (range 2-6). Eleven patients had full continence and three patients suffer occasional incontinence to liquid stools. Two patients have nocturnal seepage but all can defer the urge to defaecate by more then 15 min. There was no significant difference in physiological parameters between the two groups.