Colorectal cancer diagnosis: Pitfalls and opportunities

Table 1 Summary of findings (sensitivity, specificity, predictive values) for diagnostic tests for colorectal cancer detection evaluated by at least four primary diagnostic studies

Index test	Sensitivity	Specificity	PPV	1-NPV
Age (> 50)	91%	36%	10%	2%
Sex (male)	62%	55%	13%	3%
Family history	16%	91%	6%	4%
Weight loss	20%	89%	9%	6%
Abdominal pain	35%	59%	5%	7%
Rectal bleeding	44%	66%	7%	4%
All bleeding, dark blood	35%	85%	14%	5%
All bleeding, mixed with stool	51%	71%	6%	3%
Change in bowel habits	52%	61%	9%	4%
Diarrhoea present	20%	73%	6%	10%
Constipation	13%	72%	6%	9%
Two week rule positive	92%	42%	14%	3%
Iron deficiency anaemia	13%	92%	13%	8%
Faecal occult blood test positive
Chemical	75%	86%	28%	1%
Immunological	95%	84%	21%	0%

The results are expressed as medians or pooled estimates. Adapted from Jellema et al[24]. PPV: Positive predictive value; NPV: Negative predictive value.