Colon Cancer: Likelihood Ratios

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Prevalence

Population / Calculator	Prevalence	Comments / Study / Link
	5%
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The likelihood ratios of findings for Colon Cancer are listed below. See the left navigation bar to change the display.

Pre-Test Probability (Prevalence): %.	Post-Test Probability (Predictive Value): %.	Switch to display mode.
Note that calculating probabilities from more than one** finding is inherently inaccurate because findings are not independent. (For example, using two positive findings that share a common pathogenesis is likely to overestimate the true probability.)


Finding	Result	+LR	-LR
[ + ] Age	+ 0 -	1.4	0.3
Age > 50 Study: BMJ. 2010 Mar 31;340:c1269 PMID: 20360221
[ + ] Age	+ 0 -	1.8	0.3
Age > 60 Study: BMJ. 2010 Mar 31;340:c1269 PMID: 20360221
[ + ] Age	+ 0 -	2.4	0.6
Age > 70 Study: BMJ. 2010 Mar 31;340:c1269 PMID: 20360221
[ + ] CEA		No accuracy specified.
Carcinoembryonic antigen Study: no study specified.
[ + ] Changes in Bowel Habits	+ 0 -	1.3	0.8
Study: BMJ. 2010 Mar 31;340:c1269 PMID: 20360221
[ + ] Colonoscopy	+ 0 -	6.8	0.1
Sensitivity differs for adenoma size (<5 mm 75%, 6-9mm 85%, >10mm 95%). Study: USPSTF Modeling Report https://www.uspreventiveservicestaskforce.org/uspstf/document/modeling-report1/colorectal-cancer-screening
[ + ] Constipation	+ 0 -	0.5	1.2
Study: BMJ. 2010 Mar 31;340:c1269 PMID: 20360221
[ + ] Diarrhea	+ 0 -	0.7	1.1
Study: BMJ. 2010 Mar 31;340:c1269 PMID: 20360221
[ + ] Family History of Colon Cancer	+ 0 -	1.8	0.9
Study: BMJ. 2010 Mar 31;340:c1269 PMID: 20360221
[ + ] Fecal Occult Blood	+ 0 -	4	0.8
6-sample Study: Ann Intern Med. 2005 Jan 18;142(2):81-5. PMID: 15657155
[ + ] Fecal Occult Blood	+ 0 -	1.7	1
single sample from DRE Study: Ann Intern Med. 2005 Jan 18;142(2):81-5. PMID: 15657155
[ + ] Fecal Occult Blood	+ 0 -	5.4	0.3
guaiac-based test (note much higher sensitivity here compared to other studies) Study: BMJ. 2010 Mar 31;340:c1269 PMID: 20360221
[ + ] Fecal Occult Blood	+ 0 -	5.9	0.1
immunoassay-based test (note the very high sensitivity here) this was only in secondary referral clinics (probable bias?) Study: BMJ. 2010 Mar 31;340:c1269 PMID: 20360221
[ + ] Gender	+ 0 -	1.4	0.7
male Study: BMJ. 2010 Mar 31;340:c1269 PMID: 20360221
[ + ] Rectal bleeding	+ 0 -	1.3	0.8
for "dark blood" sens=35% / spec=85%; for "mixed with stool" sens=51% / spec=71% Study: BMJ. 2010 Mar 31;340:c1269 PMID: 20360221
[ + ] Rectal Mass	+ 0 -	2.3	0.8
note that sens for abdominal mass = 4% Study: BMJ. 2010 Mar 31;340:c1269 PMID: 20360221
[ + ] S. Bovis bacteremia		No accuracy specified.
Aside from colon cancer, other GI pathology, liver disease and HIV should be considered. Study: PMID: 16614996 Alazmi W; Bustamante M; O'loughlin C; Gonzalez J; Raskin JB Dig Dis Sci. 2006 Apr;51(4):732-6.
[ + ] Secondary Screening Referral Guideline	+ 0 -	1.6	0.2
At least one of the following: Rectal bleeding with a change in bowel habit to looser stools and/or increased frequency of defecation persistent for 6 weeks. Age threshold: all ages. Change in bowel habit as above without rectal bleeding and persistent for 6 weeks. Age threshold: over 60 years. Rectal bleeding persistently without anal symptoms. Age threshold: over 60 years. A definite palpable right-sided abdominal mass. Age threshold: all ages. A definite palpable rectal mass (not pelvic). Age threshold: all ages. Unexplained iron deficiency anaemia. In men: below 11g/dl, all ages. In women: below 10 g/dl, post menopausal. Study:* BMJ. 2010 Mar 31;340:c1269 PMID: 20360221
[ + ] Weight	+ 0 -	1.8	0.9
Study: BMJ. 2010 Mar 31;340:c1269 PMID: 20360221