'Low' faecal immunochemical test (FIT) colorectal cancer: a 4-year comparison of the Nottingham '4F' protocol with FIT10 in symptomatic patients

AIM

The aim of this work was to evaluate colorectal cancer (CRC) outcomes after 'low' (sub-threshold) faecal immunochemical test (FIT) results in symptomatic patients tested in primary care.

METHOD

This work comprised a retrospective audit of 35 289 patients with FIT results who had consulted their general practitioner with lower gastrointestinal symptoms and had subsequent CRC diagnoses. The Rapid Colorectal Cancer Diagnosis pathway was introduced in November 2017 to allow incorporation of FIT into clinical practice. The local '4F' protocol combined FIT results with blood tests and digital rectal examination (DRE): FIT, full blood count, ferritin and finger [DRE]. The outcome used was detection rates of CRC, missed CRC and time to diagnosis in local 4F protocols for patients with a subthreshold faecal haemoglobin (fHb) result compared with thresholds of 10 and 20 μg Hb/g faeces.

RESULTS

A single threshold of 10 μg Hb/g faeces identifies a population in whom the risk of CRC is 0.2%, but this would have missed 63 (10.5%) of 599 CRCs in this population. The Nottingham 4F protocol would have missed fewer CRCs [42 of 599 (7%)] despite using a threshold of 20 μg Hb/g faeces for patients with normal blood tests. Subthreshold FIT results in patients subsequently diagnosed with a palpable rectal tumour yielded the longest delays in diagnosis.

CONCLUSION

A combination of FIT with blood results and DRE (the 4F protocol) reduced the risk of missed or delayed diagnosis. Further studies on the impact of such protocols on the diagnostic accuracy of FIT are expected. The value of adding blood tests to FIT may be restricted to specific parts of the fHb results spectrum.

CT-derived measures of muscle quantity and quality predict poorer outcomes from elective colorectal surgery: a UK multicentre retrospective cohort study

PURPOSE

To assess whether preoperative radiologically defined lean muscle measures are associated with adverse clinical outcomes in patients undergoing elective surgery for colorectal cancer.

METHODS

This retrospective UK-based multicentre data collection study identified patients having had colorectal cancer resection with curative intent between January 2013 to December 2016. Preoperative computed-tomography (CT) scans were used to measure psoas muscle characteristics. Clinical records provided postoperative morbidity and mortality data.

RESULTS

This study included 1122 patients. The cohort was separated into a combined group (patients with both sarcopenia and myosteatosis) and others group (either sarcopenia or myosteatosis, or neither). For the combined group, anastomotic leak was predicted on univariate (OR 4.1, 95% CI 1.43-11.79; p = 0.009) and multivariate analysis (OR 4.37, 95% CI 1.41-13.53; p = 0.01). Also for the combined group, mortality (up to 5 years postoperatively) was predicted on univariate (HR 2.41, 95% CI 1.64-3.52; p < 0.001) and multivariate analysis (HR 1.93, 95% CI 1.28-2.89; p = 0.002). A strong correlation exists between freehand-drawn region of interest-derived psoas density measurement and using the ellipse tool (R2 = 81%; p < 0.001).

CONCLUSION

Measures of lean muscle quality and quantity, which predict important clinical outcomes, can be quickly and easily taken from routine preoperative imaging in patients being considered for colorectal cancer surgery. As poor muscle mass and quality are again shown to predict poorer clinical outcomes, these should be proactively targeted within prehabilitation, perioperative and rehabilitation phases to minimise negative impact of these pathological states.

Planned surgery in the COVID-19 pandemic: a prospective cohort study from Nottingham

PURPOSE

Globally planned surgical procedures have been deferred during the current COVID-19 pandemic. The study aimed to report the outcomes of planned urgent and cancer cases during the current pandemic using a multi-disciplinary prioritisation group.

METHODS

A prospective cohort study of patients having urgent or cancer surgery at a NHS Trust from 1st March to 30th April 2020 who had been prioritised by a multi-disciplinary COVID Surgery group. Rates of post-operative PCR positive and suspected COVID-19 infections within 30 days, 30-day mortality and any death related to COVID-19 are reported.

RESULTS

Overall 597 patients underwent surgery with a median age of 65 years (interquartile range (IQR) 54-74 years). Of these, 86.1% (514/597) had a current cancer diagnosis. During the period, 60.8% (363/597) of patients had surgery at the NHS Trust whilst 39.2% (234/597) had surgery at Independent Sector hospitals. The incidence of COVID-19 in the East Midlands was 193.7 per 100,000 population during the study period. In the 30 days following surgery, 1.3% (8/597) of patients tested positive for COVID-19 with all cases at the NHS site. Overall 30-day mortality was 0.7% (4/597). Following a PCR positive COVID-19 diagnosis, mortality was 25.0% (2/8). Including both PCR positive and suspected cases, 3.0% (18/597) developed COVID-19 infection with 1.3% at the independent site compared to 4.1% at the NHS Trust (p=0.047).

CONCLUSIONS

Rates of COVID-19 infection in the post-operative period were low especially in the Independent Sector site. Mortality following a post-operative diagnosis of COVID-19 was high.

335 Planned Surgery in the COVID-19 Pandemic: A Prospective Cohort Study from Nottingham

Introduction

Globally planned surgical procedures were deferred during the current COVID-19 pandemic. We aim to report planned urgent and cancer case outcomes during the pandemic using a multi-disciplinary prioritisation group.

Method

Prospective cohort of patients prioritised by a multi-disciplinary COVID Surgery group undergoing urgent or cancer surgery at a NHS Trust from 1^st March-30^th April 2020. 30-day post-operative rates of PCR positive and suspected COVID-19 infections, 30-day mortality and COVID-19 related deaths are reported.

Results

During the period, 597 patients underwent surgery, median age 65-years (interquartile range 54-74) of which 86% (514/597) had a cancer diagnosis. 61% (362/597) had surgery at the NHS Trust whilst 39% (234/597) had surgery at Independent Sector hospitals. The COVID-19 incidence in the East Midlands was 193.7 per 100,000 population. 30-days following surgery, 1.3% (8/597) tested COVID-19 positive with all cases at the NHS site. 30-day mortality was 0.7% (4/597). Mortality following PCR positive COVID-19 diagnosis was 25% (2/8). Including PCR positive and suspected cases 3.0% (18/597) developed COVID-19 infection, 1.3% at the independent site compared to 4.1% at the NHS Trust (p = 0.047).

Conclusions

Rates of COIVD-19 infection in the post-operative period were low especially in the Independent Sector site. Mortality following a post-operative diagnosis of COVID-19 was high.

GP access to FIT increases the proportion of colorectal cancers detected on urgent pathways in symptomatic patients in Nottingham

OBJECTIVE

Service evaluation of GP access to Faecal Immunochemical Test (FIT) for colorectal cancer (CRC) detection in Nottinghamshire and use of FIT for "rule out", "rule in" and "first test selection".

DESIGN

Retrospective audit of FIT results, CRC outcomes and resource utilisation before and after introduction of FIT in Primary Care in November 2017. Data from the new pathway up to December 2018 was compared with previous experience.

RESULTS

Between November 2017 and December 2018, 6747 GP FIT test requests yielded 5733 FIT results, of which 4082 (71.2%) were <4.0 μg Hb/g faeces, 579 (10.1%) were 4.0-9.9 μg Hb/g faeces, 836 (14.6%) were 10.0-149.9 μg Hb/g faeces, and 236 (4.1%) were ≥150.0 μg Hb/g faeces. The proportion of "rule out" results <4.0 μg Hb/g faeces was significantly higher than in the Getting FIT cohort (71.2% vs 60.4%, Chi squared 42.8, p < 0.0001) and the proportion of "rule in" results ≥150.0 μg Hb/g faeces was significantly lower (4.1% vs 8.1%, Chi squared 27.3,P < 0.0001). There was a 33% rise in urgent referrals across Nottingham overall during the evaluation period. 2 CRC diagnoses were made in 4082 patients who had FIT<4.0 μg Hb/g faeces. 58.4% of new CRC diagnoses associated with a positive FIT were early stage cancers (Stage I and II). The proportion of all CRC diagnoses that follow an urgent referral s rose after introduction of FIT.

CONCLUSIONS

FIT allows GP's to select a more appropriate cohort for urgent investigation without a large number of missed diagnoses. FIT appears to promise a "stage migration" effect which may ultimately improve CRC outcomes.

Faecal immunochemical testing and blood tests for prioritization of urgent colorectal cancer referrals in symptomatic patients: a 2-year evaluation

BACKGROUND

A novel pathway incorporating faecal immunochemical testing (FIT) for rapid colorectal cancer diagnosis (RCCD) was introduced in 2017. This paper reports on the service evaluation after 2 years of pathway implementation.

METHODS

The RCCD protocol was based on FIT, blood results and symptoms to stratify adult patients in primary care. Two-week-wait (2WW) investigation was indicated for patients with rectal bleeding, rectal mass and faecal haemoglobin (fHb) level of 10 µg Hb/g faeces or above or 4 µg Hb/g faeces or more in the presence of anaemia, low ferritin or thrombocytosis, in all other symptom groups. Patients with 100 µg Hb/g faeces or above had expedited investigation . A retrospective audit of colorectal cancer detected between 2017 and 2019 was conducted, fHb thresholds were reviewed and critically assessed for cancer diagnoses.

RESULTS

In 2 years, 14788 FIT tests were dispatched with 13361 (90.4 per cent) completed returns. Overall, fHb was less than 4 µg Hb/g faeces in 9208 results (68.9 per cent), 4-9.9 µg Hb/g in 1583 (11.8 per cent), 10-99.9 µg Hb/g in 1850 (13.8 per cent) and 100 µg Hb/g faeces or above in 720 (5.4 per cent). During follow-up (median 10.4 months), 227 colorectal cancers were diagnosed. The cancer detection rate was 0.1 per cent in patients with fHb below 4 µg Hb/g faeces, 0.6 per cent in those with fHb 4-9.9 µg Hb/g faeces, 3.3 per cent for fHb 10-99.9 µg Hb/g faeces and 20.7 per cent for fHb 100 µg Hb/g faeces or above. The detection rate in the cohort with 10-19.9 µg Hb/g faeces was 1.4 per cent, below the National Institute for Health and Care Excellence threshold for urgent referral. The colorectal cancer rate in patients with fHb below 20 µg Hb/g faeces was less than 0.3 per cent.

CONCLUSION

Use of FIT to "rule out" urgent referral from primary care misses a small number of cases. The threshold for referral may be adjusted with blood results to improve stratification .

Quantitative FIT stratification is superior to NICE referral criteria NG12 in a high-risk colorectal cancer population

BACKGROUND

Guidelines for urgent investigation of colorectal cancer (CRC) are based on age and symptom-based criteria. This study aims to compare the diagnostic value of clinical features and faecal immunochemical test (FIT) results to identify those at a higher risk of CRC, thereby facilitating effective triage of patients.

METHODS

We undertook a review of all patients referred for investigation of CRC at our centre between September 2016 and June 2018. Patients were identified using a prospectively recorded local database. We performed a logistic regression analysis of factors associated with a diagnosis of CRC.

RESULTS

One-thousand-and-seven-hundred-eighty-four patients with FIT results were included in the study. Change in bowel habit (CIBH) was the most common referring clinical feature (38.3%). Patients diagnosed with CRC were significantly older than those without malignancy (74.0 years vs 68.9 years, p = 0.0007). Male patients were more likely to be diagnosed with CRC than females (6.5% vs 2.5%, Chi-squared 16.93, p < 0.0001). CRC was diagnosed in 3.5% (24/684) with CIBH compared to 8.1% (6/74) with both CIBH and iron deficiency anaemia. No individual or combination of referring clinical features was associated with an increased diagnosis of CRC (Chi-squared, 8.03, p = 0.155). Three patients with negative FIT results (< 4 µg Hb/g faeces) were diagnosed with CRC (3/1027, 0.3%). The highest proportion of cancers detected was in the ≥ 100 µg Hb/g faeces group (55/181, 30.4%).

CONCLUSION

In a multivariate model, FIT outperforms age, sex and all symptoms prompting referral. FIT has greater stratification value than any referral symptoms. FIT does have value in patients with iron deficiency anaemia.

Thrombocytosis helps to stratify risk of colorectal cancer in patients referred on a 2-week-wait pathway

PURPOSE

Primary care studies suggest that thrombocytosis (platelet counts > 400 × 109/L) is associated with an increased risk of colorectal cancer (CRC). We aimed to establish whether this marker has significant stratification value in patients seen in secondary care.

METHODS

A retrospective review of 2991 patients referred to our colorectal 2-week-wait (2WW) pathway between August 2014 and August 2017. Patient demographics were recorded prospectively, and local electronic records systems were used to retrieve full blood counts (FBC) and cancer diagnoses. Patients with no recent platelet count at the time of referral or incomplete records were excluded.

RESULTS

2236 patients were included in this evaluation. There was no significant difference in the age distribution of those with thrombocytosis and those without. There were significantly more females in the thrombocytosis group (72.1% vs 53.9%, chi-squared 24.63, p < 0.0001). 130 CRCs were detected (5.8%) and patients with thrombocytosis were more likely to have CRC (OR 2.62, 95% CI 1.60-4.30). The CRC diagnosis rate was significantly higher in females with thrombocytosis (10.3% vs 2.9%, chi-squared 19.41, p < 0.0001) and males with thrombocytosis (16.1% vs 7.9%, chi-squared 4.62, p = 0.032).

CONCLUSION

Thrombocytosis appears to have stratification value in the 2WW population. Further evaluation of its value alone or in combination with other stratification tests is required.

Early clinical outcomes of a rapid colorectal cancer diagnosis pathway using faecal immunochemical testing in Nottingham

AIM

We introduced primary care access to faecal immunochemical testing (FIT) as a stratification tool for symptomatic patients considered to be at risk of colorectal cancer (CRC) prior to urgent referral. We aimed to evaluate clinical and pathway outcomes during the first 6 months of this novel approach.

METHOD

FIT was recommended for all patients who consulted their general practitioner with lower gastrointestinal symptoms other than rectal bleeding and rectal mass. We undertook a retrospective audit of the results of FIT, related clinical outcomes and resource utilization on prospectively logged cases between November 2017 and May 2018.

RESULTS

Of the 1862 FIT kits dispatched by post 91.4% were returned, with a median return time of 7 days (range 2-110 days); however, 1.3% of returned kits could not be analysed. FIT results ≥ 150.0 μg haemoglobin (Hb)/g faeces identified patients with a significantly higher risk of CRC (30.9% vs 1.4%, chi-square 167.1, P < 0.0001). FIT results ≥ 10.0 μg Hb/g faeces identified patients with significantly higher risk of significant noncancer bowel pathology (24.1% vs 4.9%, chi-square 73.6, P < 0.0001) and FIT results < 4.0 μg Hb/g faeces identified a group more likely to have non-CRC pathology (5.1% vs 2.4%, chi-square 3.9, P < 0.05). The CRC detection rate in 531 patients investigated after a FIT result of < 4.0 μg Hb/g faeces was 0.2%. In 899 investigated patients, a FIT result with a threshold of 4.0 μg Hb/g faeces had sensitivity 97.2% (85.5-99.9% CI), specificity 61.4% (58.1-64.7% CI), negative predictive value 99.8% (98.7-100.0% CI) and positive predictive value 9.5% (8.7-10.4% CI).

CONCLUSION

A symptomatic pathway incorporating FIT is feasible and appears more clinically effective than pathways based on age and symptoms alone.

Service evaluation of faecal immunochemical testing and anaemia for risk stratification in the 2-week-wait pathway for colorectal cancer

Background

New national guidance on urgent referral for investigation of colorectal cancer included faecal occult blood testing in 2015. A service evaluation of faecal immunochemical testing (FIT) and anaemia as risk stratification tools in symptomatic patients suspected of having CRC was undertaken.

Methods

Postal FIT was incorporated into the colorectal cancer 2-week wait (2WW) pathway for all patients without rectal bleeding in 2016. Patients were investigated in the 2WW pathway as normal, and outcomes of investigations were recorded prospectively. Anaemia was defined as a haemoglobin level below 120 g/l in women and 130 g/l in men.

Results

FIT kits were sent to 1106 patients, with an 80·9 per cent return rate; 810 patients completed investigations and 40 colorectal cancers were diagnosed (4·9 per cent). FIT results were significantly higher in patients with anaemia (median (i.q.r.) 4·8 (0·8-34·1) versus 1·2 (0-6·4) μg Hb/g faeces in those without anaemia; P < 0·001). Some 60·4 per cent of patients (538 of 891) had a result lower than 4 μg haemoglobin (Hb) per g faeces (limit of detectability), and 69·7 per cent (621 of 891) had less than 10 μg Hb/g faeces. Some 60 per cent of patients with colorectal cancer had a FIT reading of 150 μg Hb/g faeces or more. For five colorectal cancers diagnosed in patients with a FIT value below 10 μg Hb/g faeces, there was either a palpable rectal mass or the patient was anaemic. A FIT result of more than 4 μg Hb/g faeces had 97·5 per cent sensitivity and 64·5 per cent specificity for a diagnosis of colorectal cancer. A FIT result above 4 μg Hb/g faeces and/or anaemia had a 100 per cent sensitivity and 45·3 per cent specificity for colorectal cancer diagnosis.

Conclusion

FIT is most useful at the extremes of detectability; strongly positive readings predict high rates of colorectal cancer and other significant pathology, whereas very low readings in the absence of anaemia or a palpable rectal mass identify a group with very low risk. High return rates for FIT within this 2WW pathway indicate its acceptability.

Anaemia as a risk stratification tool for symptomatic patients referred via the two-week wait pathway for colorectal cancer

Introduction Anaemia is associated with cancer. In 2014 a new form was introduced in our department requesting a haemoglobin (Hb) result on every two-week wait referral for suspected colorectal cancer (CRC). The aim of this study was to review the impact of this intervention. In particular, the significance of any evidence of anaemia (without additional indices) was investigated. Methods A review was conducted of 1,500 consecutive suspected CRC referrals recorded prospectively over a 10-month period. Data on demographics, referral Hb, referral criteria and outcomes were analysed. Anaemia was defined according to World Health Organization criteria (Hb <120g/l for women, Hb <130g/l for men). Results Overall, 1,015 patients were eligible for inclusion in the study. Over a third (38.2%) were documented as anaemic on referral. These patients were three times more likely to be diagnosed with CRC than non-anaemic patients (odds ratio [OR]: 3.22, 95% confidence interval [CI]: 1.87-5.57). Using a more stringent threshold (Hb <100g/l for women and <110g/l for men), they were four times more likely to have CRC (OR: 4.27, 95% CI: 2.35-7.75). Almost a quarter (23.7%) were actually anaemic at the time of referral but not referred with anaemia. In this subgroup, there was a 2.8-fold increase in risk of CRC diagnosis compared with non-anaemic patients (adjusted OR: 2.77, 95% CI: 1.55-4.95). Conclusions Nearly a quarter of patients not referred with iron deficiency anaemia had evidence of anaemia and this was still associated with a higher rate of CRC detection. A full blood count alone might help to risk stratify symptoms such as change in bowel habit in patients on urgent pathways and identify those cases most likely to benefit from invasive investigation.

Straight-to-test colonoscopy for 2-week-wait referrals improves time to diagnosis of colorectal cancer and is feasible in a high-volume unit

AIM

We have introduced 'straight-to-test' (STT) colonoscopy as part of our 2-week-wait (2WW) pathway to address increasing numbers of urgent referrals for colorectal cancer (CRC) within the National Health Service. In this study we evaluated the ability of this initiative to shorten the time to diagnosis of CRC.

METHOD

We amended our 2WW referral form to include performance status and comorbidities. General practitioners were asked to provide data on estimated glomerular filtration rate and full blood count/ferritin. Our 2WW referrals were screened by a colorectal consultant and a nurse specialist. Those deemed unsuitable for STT were offered outpatient assessment (OPA).

RESULTS

Of 553 2WW referrals screened, 352 were considered suitable, 65 of whom failed a telephone assessment or were uncontactable, and accordingly 287 were offered the STT pathway. The STT group was significantly younger than the OPA group (median 65.9 years vs 78.7 years; P < 0.0001). STT colonoscopy significantly reduced the time to first test (13 days vs 22 days; P < 0.0001) and tissue diagnosis from the referral date (17 days vs 24.5 days; P < 0.0001). Thirty-seven (6.8%) CRCs were detected. Proportionately fewer patients in the STT pathway were managed with 'best supportive care only' compared with patients attending OPA (one of 15 vs six of 22, respectively). STT colonoscopy obviated the need for clinic attendance before testing in 287 patients, representing a potential net cost benefit of at least £48 500 in 4 months.

CONCLUSION

STT colonoscopy was safe and effective for selecting out a group of symptomatic patients who could proceed straight to endoscopic examination and receive a diagnosis more rapidly.

Colorectal cancer outcomes in patients aged over 85 years

INTRODUCTION

The prevalence of colorectal cancer is increasing in the elderly. We examined the treatment and outcomes in our institution of patients aged over 85 years with proven colorectal adenocarcinoma.

METHODS

One hundred and five patients were identified and stratified by treatment received: curative surgery (CS), other treatments (OT) or best supportive care (BSC). Data on demographics, staging, treatment and survival was collected and analysed.

RESULTS

Forty two patients received CS, 36 OT and 27 BSC. While the treated groups (CS and OT) were similar in terms of age (p=0.35) and staging (p=0.16), BSC patients were significantly older and had higher stage disease (p<0.01). Survival was significantly poorer among BSC patients, at a mean of 9.7 months (95% confidence interval [CI] 4.7-14.7) versus 41.6 months (95% CI 32.5-50.7) and OT 27.3 months (95% CI 20.4-34.1) for the CS and OT groups (p<0.001). There was no significant survival difference between CS and OT groups within 2 years of treatment (p=0.12). Thereafter, OT patients had a very similar 5-year survival to that of the BSC group, at 13% versus 43% in CS patients (p<0.001).

CONCLUSIONS

These data suggest that, up to 2 years following treatment, the risks of resectional surgery for colorectal cancer may neutralise any benefit. However, those that survive beyond this period show improvements. The challenge of improving patient selection is most acute in the growing ageing population, and highlights the current focus on presenting all treatment options to 'a reasonable patient'.

Microsatellite and chromosomal stable colorectal cancers demonstrate poor immunogenicity and early disease recurrence

OBJECTIVE

Colorectal cancers may demonstrate chromosomal instability (CSI) or microsatellite instability (MSI-H). A third group of microsatellite and chromosome stable (MACS) colorectal cancer has been described more recently. Patients with MSI-H colorectal cancers demonstrate improved outcome and a pronounced inflammatory infiltrate. Enhanced host immune response and increased immunogenicity might explain these observations. This study aims to further characterize colorectal cancer immunogenicity.

METHOD

Microsatellite stability status was determined in resected tumour samples. Microsatellite stable (MSS) tumour samples were stratified by DNA ploidy status, as determined by flow cytometry into aneuploid MSS (CSI) and diploid MSS (MACS) cancers. Lymphocyte proliferation, quantified by bromodeoxyuridine incorporation assays assessed tumour protein immunogenicity and ELISA assays quantified inflammatory cytokine release. Kaplan-Meier survival curves and multivariate analyses were used to determine prognostic value.

RESULTS

Patients with MSI-H colorectal cancer had improved outcome but those with MACS cancers undergoing curative surgery had significantly poorer disease-free survival (P = 0.002). The MACS phenotype was an independent predictor of poor outcome (HR = 2.44, 1.33-4.47, P = 0.004). Lymphocyte proliferation assays confirmed enhanced immunogenicity of MSI-H proteins and reduced immunogenicity of MACS proteins (P < 0.0001). In vitro levels of IFN-gamma (P = 0.004) and IL-18 (P < 0.0001) mirrored these differences in lymphocyte activity.

CONCLUSIONS

Stratification of colorectal cancer by MSI and ploidy status may have prognostic value in patients undergoing curative surgery. MSI-H cancers display enhanced immunogenic properties but the immune response to MACS cancers appears to be absent and this may contribute to their poor prognosis.

Microarray profiling of colorectal cancer in Bangladeshi patients

OBJECTIVE

We have carried out a retrospective analysis of all cases of colorectal cancer at the Royal London Hospital between April 1998 and March 2002 and determined the differences in presentation and outcome between Bangladeshi and Non-Bangladeshi patients. DNA microarrays were used to explain any potential genetic differences between these two groups that may explain the different phenotypes.

MATERIALS AND METHODS

We examined the colorectal database at our institution. Microarray profiles, using Affymetrix HU133A Genechips (Santa Clara, CA USA) were obtained from 10 Bangladeshi patients and an age-, sex- and stage-matched group of 10 Non-Bangladeshi patients.

RESULTS

Three hundred and sixty-three patients have been treated for colorectal cancer at the Royal London Hospital. Eighteen (5%) patients were of Bangladeshi origin. The prevalence was 27/100,000 compared to 342/100,000 of the Non-Bangladeshi population. Eleven (61%) of 18 Bangladeshi patients were under the age of 40 and 4 (22%) patients presented with locally advanced or metastatic disease. In comparison 39/345 (11%) of non-Bangladeshi patients presented with advanced disease. None of the Bangladeshi patients gave a positive family history. Microarray profiling between these two groups demonstrated 1203 differentially expressed genes (P < 0.05).

CONCLUSION

Colorectal cancer is uncommon in the Bangladeshi patients compared to the non-Bangladeshi population. This cancer presents in younger patients and at a more advanced stage. There is no positive family history within this ethnic community and therefore the cancers are sporadic. However, microarray profiling is able to delineate different gene expression between these two groups. Therefore, there should be a low threshold for investigating young Bangladeshi patients with symptoms of colorectal neoplasia and any future national screening programme should allow for ethnic variation.

Tumour-infiltrating lymphocytes in colorectal cancer with microsatellite instability are activated and cytotoxic

BACKGROUND

Patients with colorectal cancer that display high-level microsatellite instability (MSI-H) appear to have a better prognosis. This may be explained by the pronounced T cell infiltrate seen in MSI-H tumours that is related to a specific antigen-driven immune response. The nature of tumour-infiltrating lymphocytes in colorectal cancers was investigated using quantitative real-time polymerase chain reaction (PCR) and immunohistochemistry.

METHODS

Quantitative fluorescent hydrolysis probe-based reverse transcriptase-PCR assays were used to detect levels of mRNA specifying T cell markers in fresh frozen colorectal tissue from MSI-H tumours and those with little or no microsatellite instability (microsatellite stable (MSS) tumours). In addition, immunohistochemistry was performed on paraffin-embedded sections to compare expression of the same T cell markers and the activation markers granzyme B and interleukin 2 receptor alpha-subunit (IL-2Ralpha) in MSI-H and MSS tumours.

RESULTS

MSI-H tumours contained higher ratios of CD8/CD3 mRNA copy numbers than MSS tumours (P = 0.016), confirming the cytotoxic nature of lymphocyte infiltrates in this subset of colorectal cancers. Furthermore, immunohistochemistry confirmed that MSI-H tumours contained more infiltrating lymphocytes than MSS tumours, as shown by increased expression of CD3 (P = 0.003) and CD8 (P = 0.008). Consistent with other studies, the lymphocytes in MSI-H tumours were activated as indicated by significantly higher granzyme B counts (P = 0.020) and a significantly higher level of expression of IL-2Ralpha (P = 0.017).

CONCLUSION

The results support the hypothesis that MSI-H colorectal cancers may be more immunogenic than MSS tumours.

First report of a healthy Indian heterozygous for delta 32 mutant of HIV-1 co-receptor-CCR5 gene

The beta-chemokine receptor, CCR5, is a major co-receptor for macrophage tropic non-syncytia-inducing isolates of HIV-1. Recently a 32 bp homozygous deletion in the coding region of CCR5 has been reported in a very small percentage (< 1%) of Caucasian individuals who remain uninfected, despite multiple exposure to the wild-type virus. This mutant allele in the heterozygous form (CCR5/32 ccr5) was readily detected in a normal unrelated Caucasian population of European heritage with varying frequencies (13-20%). However, when a large number of the non-Caucasian population (261 Africans and 423 Asians) were screened for the presence of this deleted allele, not a single case of either homozygous or heterozygous mutant for delta 32 allele of CCR5 was detected. We screened 100 normal individuals and found a single heterozygous case with an identical 32 bp deletion in CCR5 gene reported earlier, the rest possessed wild-type alleles. This deleted gene was inherited in Mendelian fashion among the family members of this individual. Thus, the frequency of this deleted allele in India among unrelated normal individuals is likely to be very low (< 1%). We observed a moderate transdominant effect of this mutant allele in a fusion assay. Finally, we show a significant inhibition of fusion of cell membranes when the 176-bp region of CCR5 was used as an antisense.

Defective HIV-1 provirus encoding a multitarget-ribozyme inhibits accumulation of spliced and unspliced HIV-1 mRNAs, reduces infectivity of viral progeny, and protects the cells from pathogenesis

A HeLa T4 cell line containing a defective human immunodeficiency virus type 1 (HIV-1) DNA (HD4) was isolated. After transactivation with Tat, the HD4 DNA was transcribed into a single 3.7-kb mRNA that encodes a chimeric CD4/Env protein and a multitarget-ribozyme directed against multiple sites within the gp120 coding region of HIV-1 RNA (Chen et al., 1992). Early steps in HIV infection such as entry, reverse transcription, and proviral DNA formation were not affected in HD4 cells, and HD4 was efficiently transactivated after either HIV-1 or HIV-2 infections. HIV-2, which lacks all of the HIV-1-specific ribozyme target sites, replicated to high levels in HD4 cells whereas HIV-1 replication was selectively inhibited. Despite a reduced accumulation of all HIV-1 transcripts, transactivation of HD4 was efficient. Surprisingly, the most abundant, multiply spliced mRNAs were reduced even though they lack all of the ribozyme target sites. These results strongly suggest that the ribozyme co-localizes with unspliced HIV-1 pre-mRNA and/or genomic HIV-1 RNA in the nucleus. Cleavage of these precursor RNAs explains the reduction of all spliced and unspliced HIV-1 RNAs. Cleavage of genomic RNA probably contributed to the three-fold reduction in the infectivity of viral progeny. Thus, the HD4 ribozyme RNA functioned as a ribozyme in the nucleus and as a mRNA for a chimeric CD4/Env protein in the cytoplasm. Its unusual large size for a ribozyme (3.7 kb) indicates that, in the future, other antiviral proteins, like negative transdominant mutant HIV-1 proteins, may also be encoded to increase its antiviral potential in a gene therapy approach.

MCAT--a multimedia cardiac angiogram tool

In this article, we present the prototype of the Multimedia Cardiac Angiogram Tool (MCAT). The MCAT provides capabilities for reviewing angiograms recorded at a cardiac catheterization laboratory. A doctor can use MCAT to annotate angiograms with audio, text, and graphics. He/she can selectively package the annotated multimedia angiograms into a document, save it as the record for the visit or use it for case presentations, or send it to another doctor over a network. MCAT streamlines data collection at a cath lab and is intended to improve the efficiency of communication and collaboration between doctors. This paper describes the design, implementation, and future directions of the prototype.