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.