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Diagnosing colorectal cancer in primary care: the value of symptoms, faecal immunochemical tests, faecal calprotectin and anaemia
Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Family Medicine.ORCID iD: 0000-0001-8846-7681
2017 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Background: Colorectal cancer (CRC) is the third most common cancer in men and the second most common in women worldwide. Adenomas can be precursors to CRC, and inflammatory bowel disease (IBD) can present with the same symptoms as CRC. The majority of patients with CRC initially consult primary care. Symptoms associated with CRC are also common among primary care patients, but seldom caused by any significant disease. Reliable diagnostic aids would be helpful in deciding which patients to refer. Faecal immunochemical tests (FITs) are commonly used for this purpose in primary care in Sweden, but there is little evidence to support this use. Faecal calprotectin (FC) has been suggested as an additional test.

Aim: To explore how doctors in primary care investigate patients with suspected CRC, the value of FITs, symptoms and presence of anaemia in diagnosing CRC and adenomas in primary care, and whether FC tests could contribute to diagnosis.

Methods: Three studies (1-3) were carried out in Region Jämtland Härjedalen, Sweden. There was no screening programme for CRC. We used a point of care qualitative dip-stick 3-sample FIT with a cut-off of 25-50μg haemoglobin/g faeces, and a calprotectin enzyme-linked immunosorbent assay (ELISA) test with a cut-off of 100 μg/g faeces. 1: A retrospective, population-based study including all patients diagnosed with CRC or adenomas with high-grade dysplasia (HGD) during the period 2005-2009 that initially consulted primary care. Symptoms, FIT results, anaemia and time to diagnosis were retrieved from medical records. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were calculated from FIT results at the region’s health centres 2008- 2009. (Paper I.) 2: A prospective cohort study including consecutive patients where primary care doctors requested FITs and/or FC tests, at four health centres, from 30 Jan 2013 to 31 May 2014. FITs, FC tests, haemoglobin and iron deficiency tests were analysed; patients and doctors answered questionnaires about symptoms. Patients were examined with bowel imaging or followed for two years. Findings of CRC, adenomas with HGD, adenomas with low grade dysplasia (LGD) ≥1 cm and IBD were registered. (Papers II and III.) 3: A qualitative study of interviews with eleven primary care doctors. We explored what made them suspect CRC, and their practices regarding investigation and referral with particular attention to their use of FITs. Qualitative content analysis with an inductive approach was used for the analysis. (Paper IV.)

Results: 1: Paper I: Of 495 patients 323 (65.3%) started the investigation in primary care. FITs were analysed in 215. In 23 cases with CRC, FITs were negative; 15 (65.2%) had anaemia. In 33 cases with CRC, FITs were performed due to asymptomatic anaemia; 10 (30.3%) had negative FITs. The time from start of investigation, to the diagnosis of CRC or adenomas with HGD, was significantly longer for patients with negative FITs.

2: 377 patients (9 diagnosed with CRC, 10 with IBD) were included. Paper II: Concordance of positive answers about symptoms from patients and doctors was generally low. Rectal bleeding (recorded by 43.5% of patients and 25.6% of doctors) was the only symptom related to CRC and IBD. The FIT showed a better PPV than rectal bleeding for CRC and IBD. When patients recorded rectal bleeding, the FIT had a PPV of 22.6% and a NPV of 98.9% for CRC and IBD. Paper III: The best test for detecting CRC and IBD was the combination of a positive FIT and/or anaemia with a sensitivity, specificity, PPV and NPV of 100%, 61.7%, 11.7% and 100% respectively. The FC test had no additional value to the FIT alone. The sensitivity, specificity, PPV and NPV of the FIT for CRC in study 1 was estimated at 88.4%, 73.3%, 6.2% and 99.7% respectively. In study 2, corresponding figures were 88.9%, 67.4%, 6.3% and 99.6% respectively.

3: Paper IV: We identified four categories: “Careful listening – with awareness of the pit-falls”, “tests can help – the FIT can also complicate the diagnosis”, “to refer or not to refer – safety margins are necessary”, and “growing more confident – but also more humble”. All doctors had found their own way to handle FIT results in the absence of guidelines.

Conclusion: The diagnostic process when suspecting CRC can be described as navigating uncertain waters with safety margins. FITs were often used by primary care doctors but with considerable variations in interpretation and handling of results. Rectal bleeding was the only symptom related to CRC and IBD, but the FIT showed a better PPV than rectal bleeding. The combination of a negative FIT and no anaemia may be useful as a rule-out test when CRC is suspected in primary care, and this potentially also applies when patients present with rectal bleeding. Further studies are needed to confirm this and to determine the optimal FIT cut-off value for this use. 

Place, publisher, year, edition, pages
Umeå: Umeå Universitet , 2017. , 69 p.
Series
Umeå University medical dissertations, ISSN 0346-6612 ; 1893
Keyword [en]
colorectal cancer, faecal immunochemical tests, faecal calprotectin, anaemia, symptomatic patients, rectal bleeding, primary care
National Category
Family Medicine Cancer and Oncology
Identifiers
URN: urn:nbn:se:umu:diva-133628ISBN: 978-91-7601-680-0 (print)OAI: oai:DiVA.org:umu-133628DiVA: diva2:1088951
Public defence
2017-05-19, Hörsalen Snäckan, Östersunds sjukhus, Östersund, 13:00 (Swedish)
Opponent
Supervisors
Available from: 2017-04-28 Created: 2017-04-18 Last updated: 2017-04-28Bibliographically approved
List of papers
1. Immunochemical faecal occult blood tests in primary care and the risk of delay in the diagnosis of colorectal cancer
Open this publication in new window or tab >>Immunochemical faecal occult blood tests in primary care and the risk of delay in the diagnosis of colorectal cancer
Show others...
2013 (English)In: Scandinavian Journal of Primary Health Care, ISSN 0281-3432, E-ISSN 1502-7724, Vol. 31, no 4, 209-214 p.Article in journal (Refereed) Published
Abstract [en]

Objective. To evaluate the value, risks, and shortcomings of immunochemical faecal occult blood tests (iFOBTs) in the diagnosis of colorectal cancer (CRC) and adenomas with high-grade dysplasia (HGD) in patients initially presenting to primary care. Design. A retrospective population-based study. Setting and subjects. All 495 cases of CRC and adenomas with HGD diagnosed in the county of Jamtland, Sweden from 2005 to 2009. Results. Of 495 patients 323 (65%) initially presented to primary care. IFOBTs were performed in 215 of 323 (67%) patients. The sensitivity of iFOBT for CRC and adenomas with HGD was 88% (83% when patients with a history of rectal bleeding were excluded). Of 34 patients with anaemia found en passant, 10 had negative iFOBTs. Time to diagnosis was longer for patients with negative iFOBTs (p < 0.0005). Conclusion. IFOBT might be helpful in selecting which patients to refer for colonoscopy. However, iFOBT has a limited sensitivity as a diagnostic test for CRC and adenomas with HGD. Relying only on iFOBT for colonoscopy referral could delay diagnosis, especially for patients with anaemia found en passant.

Place, publisher, year, edition, pages
Informa Healthcare, 2013
Keyword
Colorectal neoplasms, diagnosis, general practice, occult blood, signs and symptoms
National Category
Cancer and Oncology Public Health, Global Health, Social Medicine and Epidemiology
Identifiers
urn:nbn:se:umu:diva-83695 (URN)10.3109/02813432.2013.850205 (DOI)000328114500009 ()
Available from: 2013-12-04 Created: 2013-12-04 Last updated: 2017-04-26Bibliographically approved
2. Diagnosis of colorectal cancer: Patients' symptoms and faecal immunochemical test results in primary care. A prospective study
Open this publication in new window or tab >>Diagnosis of colorectal cancer: Patients' symptoms and faecal immunochemical test results in primary care. A prospective study
(English)Manuscript (preprint) (Other academic)
National Category
Family Medicine
Identifiers
urn:nbn:se:umu:diva-133624 (URN)
Available from: 2017-04-18 Created: 2017-04-18 Last updated: 2017-04-26
3. Diagnosing colorectal cancer and inflammatory bowel disease in primary care: The usefulness of tests for faecal haemoglobin, faecal calprotectin, anaemia and iron deficiency: A prospective study
Open this publication in new window or tab >>Diagnosing colorectal cancer and inflammatory bowel disease in primary care: The usefulness of tests for faecal haemoglobin, faecal calprotectin, anaemia and iron deficiency: A prospective study
2017 (English)In: Scandinavian Journal of Gastroenterology, ISSN 0036-5521, E-ISSN 1502-7708, Vol. 52, no 1, 69-75 p.Article in journal (Refereed) Published
Abstract [en]

OBJECTIVE: Abdominal complaints are common reasons to consult primary care but they are seldom caused by colorectal cancer (CRC), high-risk adenomas (HRAs), or inflammatory bowel disease (IBD). Reliable diagnostic aids would be helpful in deciding which patients to refer for bowel imaging. Our aim was to assess the value of a faecal immunochemical test (FIT) and a faecal calprotectin (FC) test in detecting CRC, HRAs and IBD in primary care, and the value of combining these tests with anaemia and iron-deficiency tests.

MATERIALS AND METHODS: This prospective study included 373 consecutive patients that received a FIT or a FC test ordered by a primary care physician. We collected samples for FITs, FC tests, full blood counts and iron-deficiency tests. Physicians were instructed to refer patients with a positive FIT or FC test (cut-off ≥100μg/g) for bowel imaging. The patients' presenting symptoms were recorded. Patients were followed for 2 years.

RESULTS: The best test for detecting CRC and IBD was the combination of the FIT and haemoglobin concentration. This test had a sensitivity, specificity, positive predictive value and negative predictive value of 100%, 61.7%, 11.7% and 100%, respectively. The FIT detected a significantly larger proportion of CRC, HRAs and IBD than the FC test (0.92 versus 0.46, 95% confidence interval 0.22-0.67).

CONCLUSION: A negative FIT combined with a normal haemoglobin concentration could rule out CRC and IBD with a high degree of safety. This could be useful in prioritising referrals for bowel imaging from primary care.

Keyword
Anaemia, faecal calprotectin, colorectal cancer, faecal immunochemical test, inflammatory bowel disease, occult blood, primary care
National Category
Gastroenterology and Hepatology
Identifiers
urn:nbn:se:umu:diva-128594 (URN)10.1080/00365521.2016.1228120 (DOI)000392486600013 ()27623716 (PubMedID)
Available from: 2016-12-07 Created: 2016-12-07 Last updated: 2017-04-18Bibliographically approved
4. Could it be colorectal cancer?: general practitioners' use of the faecal occult blood test and decision making - a qualitative study
Open this publication in new window or tab >>Could it be colorectal cancer?: general practitioners' use of the faecal occult blood test and decision making - a qualitative study
2015 (English)In: BMC Family Practice, ISSN 1471-2296, E-ISSN 1471-2296, Vol. 16, no 1, 153-161 p.Article in journal (Refereed) Published
Abstract [en]

BACKGROUND: Abdominal complaints are common reasons for contacting primary care physicians, and it can be challenging for general practitioners (GPs) to identify patients with suspected colorectal cancer (CRC) for referral to secondary care. The immunochemical faecal occult blood test (iFOBT) is used as a diagnostic aid in primary care, but it is unclear how test results are interpreted. Studies show that negative tests are associated with a risk of delayed diagnosis of CRC and that some patients with positive tests are not investigated further. The aim of this study was to explore what makes GPs suspect CRC and to investigate their practices regarding investigation and referral, with special attention on the use of iFOBTs.

METHOD: Semi-structured individual interviews were conducted with eleven purposely selected GPs and registrars in Region Jämtland Härjedalen, Sweden, and subjected to qualitative content analysis.

RESULTS: In the analysis of the interviews four categories were identified that described what made the physicians suspect CRC and their practices. Careful listening-with awareness of the pitfalls: Attentive listening was described as essential, but there was a risk of being misled by, for example, the patient's own explanations. Tests can help-the iFOBT can also complicate the diagnosis: All physicians used iFOBTs to various extents. In the absence of guidelines, all found their own ways to interpret and act on the test results. To refer or not to refer-safety margins are necessary: Uncertainty was described as a part of everyday work and was handled in different ways. Common vague symptoms could be CRC and thus justified referral with safety margins. Growing more confident-but also more humble: With increasing experience, the GPs described becoming more confident in their decisions but they were also more cautious.

CONCLUSIONS: Listening carefully to the patient's history was essential. The iFOBT was frequently used as support, but there were considerable variations in the interpretation and handling of the results. The diagnostic process can be described as navigating uncertain waters with safety margins, while striving to keep the patient's best interests in mind. The iFOBT may be useful as a diagnostic aid in primary care, but more research and evidence-based guidelines are needed.

Place, publisher, year, edition, pages
BioMed Central, 2015
Keyword
Colorectal neoplasms, Diagnostic techniques and procedures, Occult blood, General practitioners, Primary health care, Qualitative research
National Category
Family Medicine
Identifiers
urn:nbn:se:umu:diva-111201 (URN)10.1186/s12875-015-0371-1 (DOI)000363448700001 ()26498374 (PubMedID)
Note

This study was made possible by unrestricted grants from the Region Jämtland Härjedalen, the Regional Cancer Centre North, the Northern County Councils (Visare Norr), the Swedish Society of Medicine, the Cancer Research Foundation in Northern Sweden, and the Jämtland County Cancer and Nursing Fund.

Available from: 2015-11-11 Created: 2015-11-09 Last updated: 2017-04-26Bibliographically approved

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