Search PubMed⌕ Search

Biomedical subjects

W M Thomas

Publications and source records attributed to W M Thomas.

At least 37 records · Page 2Linked to original sources
PubMed1994

Population screening for colorectal cancer: comparison between guaiac and immunological faecal occult blood tests.

There is concern about the low sensitivity of the guaiac-based Haemoccult test in mass population faecal occult blood (FOB) screening for the early detection of colorectal carcinoma. Hemeselect, an immunological FOB test, has been shown to be more sensitive for symptomatic colorectal cancer and may prove to be a more reliable screening method. In Brighton and Guildford, 4018 asymptomatic subjects aged 50-75 years were offered screening with Haemoccult and Hemeselect. A total of 1489 (37.7 per cent) completed both tests, of which 17 (1.1 per cent) were positive for Haemoccult and 145 (9.7 per cent) positive for Hemeselect (a total of 148 subjects had positive tests). Seven subjects (4.7 per cent) refused to be investigated. Colonic investigation in the remainder revealed nine cancers and 49 patients with 67 adenomas (32 tumours 1 cm or more in size). All cancers (Dukes A, six; B, one; C, two) were detected by Hemeselect (positive predictive value 6.2 per cent) but only one patient was Haemoccult positive (positive predictive value 5.9 per cent). Hemeselect detected 65 adenomas (31 of 1 cm or more) in 48 patients (positive predictive value 33.1 per cent) compared with 11 adenomas (seven of 1 cm or more) in eight patients who were positive for Haemoccult (positive predictive value 47.1 per cent). The test specificity for neoplasia was respectively 94.9 and 99.6 per cent. The Hemeselect positive rate is high but its substantial positive predictive value for cancer warrants continuing evaluation.

Aged↗
PubMed1994

The yield of flexible fiberoptic sigmoidoscopy in the detection of asymptomatic colorectal neoplasia.

Recent evidence of a reduction in mortality rates from distal colorectal cancers in populations screened by rigid sigmoidoscopy suggests that further benefits may be achieved by the use of fiberoptic sigmoidoscopy as the screening modality. However, there is limited evidence as to the expected yield of neoplasia using the standard 60-cm instrument. The aim of this study was to determine the yield of neoplasia in an asymptomatic population in the at-risk age group undergoing fiberoptic sigmoidoscopy. Recruitment into the screening program was among State Department personnel. In total, 4,216 asymptomatic subjects (50-65 years) were offered flexible sigmoidoscopic screening performed following a simple enema bowel preparation. Those in whom a neoplastic condition was identified underwent further investigation (colonoscopy or barium enema). Of those offered screening 4,005 (95%) underwent the examination. Eleven carcinomas were detected at flexible sigmoidoscopy and two carcinomas were detected at further investigation in subjects with rectosigmoid polyps. The overall detection rate of carcinomas was 3.2 per 1,000 subjects screened. Histologically proven adenomas were detected in 217 subjects, 5.4% of the population screened. In this cohort of individuals flexible sigmoidoscopy appears to have been an acceptable form of screening. The detection rate of neoplasia, particularly colorectal adenomas, is higher than that reported from studies of fecal occult blood screening.

Adenoma↗
PubMed1994

Haemoccult screening for colorectal cancer: the effect of dietary restriction on compliance.

The aim of this study was to examine the effect of dietary restrictions on compliance with Haemoccult screening for colorectal carcinoma. One-hundred-and-fifty-three individuals were randomly allocated to perform Haemoccult tests with or without dietary restrictions, over 3 or 6 days. Those who failed to return completed tests within 6 weeks were sent a reminder letter. A small but significant improvement in compliance when testing over a 3-day period has been previously demonstrated but this difference was not seen in this study because of the small sample size. Overall, 72.8% compliance was achieved in those who were not asked to exclude certain foods during the test period compared with 51.8% in those in whom dietary restriction was requested (chi 2 = 7.45, P < 0.01). In a British population compliance with Haemoccult screening is adversely affected by the imposition of dietary restrictions.

Aged↗
PubMed1993

Change towards earlier stage at presentation of colorectal cancer.

A study was carried out to investigate the change in stage at presentation of patients with colorectal cancer over 10 years. Cases were identified from the control group of subjects enrolled into a randomized controlled study based on Haemoccult screening for colorectal neoplasia. Of 405 subjects in the control group (presenting with symptomatic colorectal cancer, 206 presented before 1989 and 199 since then. The number of patients with Dukes' stage A carcinoma diagnosed since 1989 rose from 21 (10.4 per cent) to 35 (18.1 per cent); this change occurred for rectosigmoid tumours (9.9 per cent before 1989, 28 per cent after 1989) but not for colonic cancer (10.9 per cent before 1989, 11.5 per cent thereafter). An increase in the proportion of patients with symptomatic early-stage rectosigmoid cancer has been observed in the past 10 years. No such change occurred in those with colonic cancer. This may reflect a change in awareness of te disease and its symptoms by patients and general practitioners.

Adult↗
PubMed1993

Is dietary restriction always necessary in Haemoccult screening for colorectal neoplasia?

Certain dietary constituents may cause guaiac-based faecal occult blood tests to be positive in the absence of blood loss. In a randomized controlled study of Haemoccult screening for the early detection of colorectal cancer, a policy of retesting with appropriate dietary restriction is used to minimize false-positive results. Delay associated with the retesting protocol may cause considerable anxiety. The aim of the study was to determine the likelihood of an initial positive result remaining positive after retesting. One-hundred-and-thirteen of 137 (35.6%) subjects whose initial test was < 5 squares positive remained positive in contrast to 52/59 (88.1%) with > or = 5 squares positive, a significantly higher proportion (P < 0.001). This suggests that if five or more test squares are positive, then dietary interference is unlikely to be responsible. We conclude that, if dietary restriction retesting is practiced, individuals with strongly positive tests may be offered investigation without retesting, thus reducing their delay to further investigation.

Colorectal Neoplasms↗
PubMed1992

Screening for colorectal carcinoma: an analysis of the sensitivity of haemoccult.

The sensitivity of Haemoccult for asymptomatic colorectal carcinoma has been estimated in a large randomized controlled trial of mass population screening, with a minimum follow-up of 2 years. A total of 111 cancers were diagnosed in those who completed the screening tests; of these, 36 appear to have been missed by Haemoccult and 75 were detected by the test, giving an overall sensitivity of 67.6 per cent. Haemoccult was shown to be significantly more sensitive for carcinoma of the sigmoid and descending colon than for rectal or right-sided cancers (81 versus 45 and 47 per cent, respectively). The sensitivity was higher when tests were completed over 6 rather than 3 days (74 versus 65 per cent), but this difference was not statistically significant. There was no evidence for a detrimental effect on tumour stage of a false-negative Haemoccult test; indeed, a higher proportion of the interval cancers were Dukes' A tumours than cancers in the control group.

Aged↗
PubMed1992

Chemical and immunological testing for faecel occult blood: a comparison of two tests in symptomatic patients.

An established chemical faecal occult blood test (Haemoccult prepared without rehydration) has been compared with a new immunological test (Hemeselect) in patients referred for investigation of lower gastro-intestinal symptoms. Hemeselect was shown to have a higher sensitivity for colorectal carcinoma (94.0% compared with 58.0%), the greatest difference in sensitivity between the two tests being for rectal cancers. Similarly Hemeselect was more sensitive than Haemoccult for colorectal adenomas (66.6% vs 33.3%), and for inflammatory bowel disease (88.9% vs 33.3%). However the enhanced sensitivity of Hemeselect for colorectal neoplasia and inflammatory bowel disease was accompanied by a significant increase in the overall rate of positive reactions (32.8% of patients had a positive Hemeselect reaction compared with 14.8% who had a positive Haemoccult test), and a reduction in specificity (84.1% for Hemeselect vs 96.0% for Haemoccult). Hemeselect is a more sensitive indicator of colorectal neoplasia in symptomatic subjects, trials of its use as a screening test for asymptomatic neoplasia appear justified.

Adenoma↗
PubMed1992

Somatostatin receptors in human colorectal cancer.

We have previously reported that somatostatin may reduce tumour cellular proliferation in patients with colorectal carcinoma. However, it is not known what proportion of primary colorectal cancers express somatostatin receptors. We have therefore evaluated somatostatin receptor status in 50 primary colorectal cancers. Twelve (24%) of the cancers were shown to be somatostatin receptor positive. There was no correlation between receptor status and tumour stage or grade.

Autoradiography↗
PubMed1992

Serum gastrin concentrations in colorectal cancer patients.

Fasting serum gastrin concentrations were shown to be elevated in colorectal cancer patients compared with controls (P = 0.0037), which was mainly accounted for by a subgroup of patients who had significantly elevated levels. In cancer patients there was no difference in gastrin concentrations in blood taken from a tumour-draining mesenteric vein and from a peripheral vein at the time of colonic resection. Serum gastrin concentrations were significantly lower after apparently curative resection for colorectal cancer (P = 0.028), suggesting that the elevated serum gastrin seen in these patients may be due, at least in part, to secretion of gastrin by the tumour.

Adult↗
PubMed1991

Failure of CA19-9 to detect asymptomatic colorectal carcinoma.

Serum CA19-9 levels have been measured in 34 patients with asymptomatic colorectal cancer, 39 age and sex matched subjects with healthy colons (as assessed at full colonoscopy) and 55 patients known to have liver metastases from primary colorectal cancers. In subjects with asymptomatic cancer the median CA19-9 was 12.75 U ml-1 (0.0-280.7 U ml-1), in the healthy controls the median CA19-9 was 12.80 U ml-1 (0.0-88.9 U ml-1) and in those with liver metastases was 62.5 U ml-1 (4.8-458.0 U ml-1). Levels were significantly higher in patients with metastatic disease than in patients with asymptomatic tumours or the healthy controls, however there was no significant difference between the asymptomatic group and the controls. Using an upper limit of normal of 37 U ml-1, the sensitivity of CA19-9 was 60.3% for the detection of colorectal cancer with liver metastases but only 17.6% for asymptomatic cancer. Serum CA19-9 estimation is of no value as a means of screening for asymptomatic colorectal cancer.

Adult↗
PubMed1991

A multicentre controlled clinical trial of high-volume fresh frozen plasma therapy in prognostically severe acute pancreatitis.

Fresh frozen plasma (FFP) has been proposed as a specific therapy for acute pancreatitis. It may replenish important circulating proteins, particularly the naturally occurring anti-protease system. To investigate this potential therapy, 72 patients with predicted severe disease were selected from 301 admissions with acute pancreatitis using the modified Glasgow prognostic scoring system. They were randomised within 6 h of diagnosis to receive FFP (8 units daily for 3 days) or a similar volume of colloid control as part of their intravenous fluid therapy. Clinical progress was monitored and specific blood proteins were measured on days 1, 3 and 7. FFP therapy significantly increased the day 3 concentrations of some of the acute phase proteins (C1-reactive protein P less than 0.02, D-dimer P less than 0.05 and fibrinogen P less than 0.05) as well as some proteins which showed a fall in circulating concentration during the early stages of the disease (alpha 2 macroglobulin P less than 0.001, antithrombin III P less than 0.01 and fibronectin P less than 0.001). However, there was no significant difference between the two groups in terms of clinical outcome. Mortality was 20% in patients who received FFP and 18% in the colloid control group. Despite the ability of FFP therapy to supplement circulating concentrations of several potentially useful proteins during acute pancreatitis, it does not appear to improve clinical outcome.

Acute Disease↗
PubMed1990

Faecal occult blood screening for colorectal neoplasia: a randomized trial of three days or six days of tests.

Haemoccult, a guaiac test for faecal occult blood, detects 56-78 per cent of asymptomatic carcinomas when performed over 3 days. In patients with known colorectal cancer the sensitivity of the test for neoplasia is increased by extending the test period to 6 days. We report the first randomized comparison of 3 day with 6 day testing in asymptomatic individuals. 35,184 age and sex matched individuals were randomly allocated to receive Haemoccult over 3 or 6 days. The tests were completed by 10,176 (57.8 per cent) of the 17,616 offered 3 day Haemoccult and 9461 (53.9 per cent) of the 17,568 offered 6 day Haemoccult, a significant decrease in compliance (P less than 0.001). Of the 3 day Haemoccult tests 131 (1.29 per cent) were positive, significantly fewer than the 160 (1.69 per cent) positive tests after 6 day Haemoccult (0.01 less than P less than 0.02). Investigation of subjects with a positive test revealed 20 carcinomas (1.14 per 1000 offered and 1.97 per 1000 completing the test) in the 3 day group and 24 carcinomas (1.37 per 1000 offered and 2.54 per 1000 completing the test) after 6 day Haemoccult tests (0.5 less than P less than 0.7 for those offered the test and 0.3 less than P less than 0.5 for those completing it). After 3 day Haemoccult 112 adenomas in 76 persons were detected (4.31 per 1000 offered and 7.47 per 1000 completing the test). In the 6 day group 123 adenomas in 83 persons (4.72 per 1000 offered and 8.77 per 1000 completing the test) were detected (0.5 less than P less than 0.7 for those offered the test and 0.3 less than P less than 0.5 for those completing it). Large adenomas were found in 27 individuals after 3 day testing (1.53 per 1000 offered the test and 2.65 per 1000 completing it) and in 35 individuals after 6 day testing (1.99 per 1000 offered the test and 3.70 per 1000 completing it) (0.3 less than P less than 0.5 for those offered the test and 0.1 less than P less than 0.2 for those completing it). This study has not demonstrated a significant increase in the yield of neoplasia in asymptomatic subjects offered Haemoccult over 6 days. However there was a significant decrease in compliance and a higher rate of colonscopy in those offered 6 day testing.

Adenoma↗
PubMed1990

Comparison of Coloscreen Self-Test and Haemoccult faecal occult blood tests in the detection of colorectal cancer in symptomatic patients.

The usefulness of faecal occult blood tests is limited by their acceptability to patients. Standard tests require the collection of a stool sample which may inhibit compliance. Self-read tests which avoid this step have therefore been devised. Coloscreen Self-Test (CST) and Haemoccult, which may be regarded as the standard slide test, were offered to 450 consecutive patients attending surgical outpatient clinics with symptoms suggestive of lower gastrointestinal disease. Both tests were successfully completed by 383 patients. Although 262 (68 per cent) patients indicated that they preferred CST this was not reflected in the overall compliance to the two tests (CST 86 per cent, Haemoccult 90 per cent). CST gave a positive result in only eight out of 24 patients with a colorectal cancer (sensitivity = 33 per cent) compared with 13 out of 24 for Haemoccult (sensitivity = 54 per cent). CST had no advantage from increased compliance to outweigh its lower sensitivity.

Colorectal Neoplasms↗
PubMed1990

Role of upper gastrointestinal investigations in a screening study for colorectal neoplasia.

Should patients with positive faecal occult blood screening tests who are free of colorectal neoplasia undergo upper gastrointestinal investigation? Altogether 16,985 faecal occult blood tests were completed in a group of 18,818 asymptomatic patients (45-75 years) offered screening at two yearly intervals. A total of 447 (2.6%) were positive and underwent large bowel investigations. No neoplastic disease was identified in 283 (63%) of them. Fourteen (5%) also underwent gastroscopy for upper gastrointestinal symptoms, benign conditions were identified in five and a gastric carcinoma in one. No further investigations were instituted in the remaining 269 subjects who have now been followed up for a median period of 5 years (2-8 years). Five have been referred for benign upper gastrointestinal conditions, but none for upper gastrointestinal malignancy. Thirty one subjects have died - one from gastric cancer (a patient who had undergone a previous partial gastrectomy for a duodenal ulcer and who had persistent upper gastrointestinal symptoms). The remaining deaths were unrelated to the upper gastrointestinal tract. Nineteen people who have left the trial area have been monitored for the development of malignant disease; none have presented with upper gastrointestinal malignancy. These data support the view that upper gastrointestinal investigations need not be performed routinely in this group of subjects, but may be reserved for those with relevant symptoms.

Aged↗
PubMed1989

Randomised, controlled trial of faecal occult blood screening for colorectal cancer. Results for first 107,349 subjects.

To assess the effectiveness of screening by faecal occult blood tests, 107,349 people without symptoms of colorectal disease identified from general practitioner records have been randomly allocated to test and control groups. 53,464 test subjects were invited to carry out the screening test; 27,651 (53%) of the 52,258 who received the tests did so. Further investigation of the 618 (2.3%) with positive tests showed 63 cancers (52% stage A) and 367 adenomas (266 subjects). Rescreening of subjects with negative results every 2 years (9510 first rescreen, 3639 second) has shown a significant fall in the rate of positive results (1.7% of 7344; 0.3% of 2906). Cancers have also been diagnosed in 20 subjects presenting in the interval between a negative test and rescreening, and in 83 non-responders. The incidence of cancer in the control group (123 subjects; 10.6% stage A) was 0.72 per 1000 person-years. Cancers detected by screening were at a less advanced pathological stage, but it is too early to show any effect of screening on mortality from colorectal cancer.

Adenocarcinoma↗