Most bowel cancer symptoms do not indicate colorectal cancer and polyps: a systematic review

<p>Abstract</p> <p>Background</p> <p>Bowel symptoms are often considered an indication to perform colonoscopy to identify or rule out colorectal cancer or precancerous polyps. Investigation of bowel symptoms for this purpose is recommended by numerous clinical guidelines. However, the evidence for this practice is unclear. The objective of this study is to systematically review the evidence about the association between bowel symptoms and colorectal cancer or polyps.</p> <p>Methods</p> <p>We searched the literature extensively up to December 2008, using MEDLINE and EMBASE and following references. For inclusion in the review, papers from cross sectional, case control and cohort studies had to provide a 2×2 table of symptoms by diagnosis (colorectal cancer or polyps) or sufficient data from which that table could be constructed. The search procedure, quality appraisal, and data extraction was done twice, with disagreements resolved with another reviewer. Summary ROC analysis was used to assess the diagnostic performance of symptoms to detect colorectal cancer and polyps.</p> <p>Results</p> <p>Colorectal cancer was associated with rectal bleeding (AUC 0.66; LR+ 1.9; LR- 0.7) and weight loss (AUC 0.67, LR+ 2.5, LR- 0.9). Neither of these symptoms was associated with the presence of polyps. There was no significant association of colorectal cancer or polyps with change in bowel habit, constipation, diarrhoea or abdominal pain. Neither the clinical setting (primary or specialist care) nor study type was associated with accuracy.</p> <p>Most studies had methodological flaws. There was no consistency in the way symptoms were elicited or interpreted in the studies.</p> <p>Conclusions</p> <p>Current evidence suggests that the common practice of performing colonoscopies to identify cancers in people with bowel symptoms is warranted only for rectal bleeding and the general symptom of weight loss. Bodies preparing guidelines for clinicians and consumers to improve early detection of colorectal cancer need to take into account the limited value of symptoms.</p

Diagnostic accuracy systematic review of rectal bleeding in combination with other symptoms, signs and tests in relation to colorectal cancer

Background: Rectal bleeding is a recognised early symptom of colorectal cancer. This study aimed to assess the diagnostic accuracy of symptoms, signs and diagnostic tests in patients with rectal bleeding in relation to risk of colorectal cancer in primary care. methods: Diagnostic accuracy systematic review. Medline (1966 to May 2009), Embase (1988 to May 2009), British Nursing Index (1991 to May 2009) and PsychINFO (1970 to May 2009) were searched. We included cohort studies that assessed the diagnostic utility of rectal bleeding in combination with other symptoms, signs and diagnostic tests in primary care. An eight-point quality assessment tool was produced to assess the quality of included studies. Pooled positive likelihood ratios (PLRs), sensitivities and specificities were calculated. results: Eight studies incorporating 2323 patients were included. Average weighted prior probability of colorectal cancer was 7.0% (range: 3.3–15.4%, median: 8.1%). Age 60 years (pooled PLR: 2.79, 95% confidence interval (CI) 2.00–3.90), weight loss (pooled PLR: 1.89, 95% CI: 1.03–3.07) and change in bowel habit (pooled PLR: 1.92, 95% CI: 0.54–3.57) raise the probability of colorectal cancer into the range of referral to secondary care but do not conclusively ‘rule in’ the diagnosis. Presence of severe anaemia has the highest diagnostic value (pooled PLR: 3.67, 95% CI: 1.30–10.35), specificity 0.95 (95% CI: 0.93–0.96), but still only generates a post-test probability of 21.6%. conclusions: In patients with rectal bleeding who present to their general practitioner, additional ‘red flag’ symptoms have modest diagnostic value. These findings have implications in relation to recommendations contained in clinical practice guidelines

El fundamento científico de la función de filtro del médico general The scientific basis for the gatekeeping role of general practicioners

Los servicios sanitarios cuentan con niveles de atención, lo que optimiza los resultados. Los niveles tienen "filtros" que aumentan la prevalencia de enfermedad entre los pacientes que llegan a niveles sucesivamente altos. En este trabajo se justifica la existencia del filtro del médico general con respecto al especialista y al hospital por el aumento de la prevalencia de enfermedad en la población derivada de primaria a hospitalaria. Se utilizan ejemplos empíricos respecto al dolor abdominal, dolor precordial y hemorragia rectal. En este último ejemplo, la prevalencia del cáncer de recto y de sigma pasa del 0,1% en la población al 2% en la consulta del médico general (por efecto del filtro personal y familiar) y al 36% en la consulta del especialista (por efecto del filtro del médico general). La selección aumenta el valor predictivo positivo de las pruebas diagnósticas que solicita el especialista, y evita el contacto innecesario con los especialistas a muchos pacientes con hemorragia rectal por causa benigna, que permanecen en su nivel (de la familia, o del médico general).<br>Health services are organized by levels of care, which improves outcomes. These levels are "filters" that lead to a progressive increase in the prevalence of diseases in higher levels of care. We studied and justified the role of the general practitioner as filter, or gatekeeper, to specialists and hospitals. This role leads to greater prevalence of diseases in the referral population. We analyzed empirical data on abdominal pain, chest pain and rectal bleeding as examples. As to rectal bleeding, the prevalence of rectum and sigma carcinomas increases from 0.1% in the population, to 2% in general practitioners' waiting rooms (as a consequence of personal and family filters), and to 36% in specialists' waiting rooms (as a consequence of the gate-keeping role general practitioners play). This increase in prevalence improves the positive predictive value of the specialist's diagnostic testing, and patient selection avoids unnecessary contacts of specialists with patients having benign causes of rectal bleeding (who remain at their appropriate family or general practitioners' level)