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.

Table 2 Main factors associated with patient delay

Increases delay	Reduces delay
Appraisal delay
Symptoms attributed to minor illness Lack of knowledge or failed to recognize symptom severity Assumed to be part of the ageing process Non-specific symptoms (altered bowel habits, unexplained weight loss) Self-treatment	Specific symptoms (rectal bleeding, abdominal pain) Symptoms frequent, severe or affect the person’s daily life Pain, vomiting and intestinal obstruction as initial symptoms
Illness delay
Younger patients Low socioeconomic status Lower educational level Rural areas Lack of additive private health insurance Family history of cancer	Comorbidity High educational level Retirement
Behavioural delay
Fear of pain Fear of cancer Fear of unpleasant or embarrassing investigations Denial of symptoms	Social support Disclosure of symptoms to someone close Knowing a person with CRC
Scheduling delay
Too busy to visit Unpleasant or embarrassing visit	Trust in GP

CRC: Colorectal cancer; GP: General practitioner.

Table 3 Main factors associated with practitioner delay

Increases delay	Reduces delay
Lack of continuity of care Frequent attendance Patient’s socioeconomic status (lower) Initial misdiagnosis Failure to examine or investigate Inaccurate or inadequate tests Co-morbidities Elderly patients Psychiatric co-morbidities	Site (rectum) Experience Use of referral guidelines Suspected CRC diagnosis in the referral Urgent referral to hospital

CRC: Colorectal cancer.

Table 4 National Institute for Health and care excellence referral criteria[7]

High risk referral criteria (any)
Patients ≥ 40 yr with rectal bleeding and a change of bowel habits persisting ≥ 6 wk
Patients ≥ 60 yr with rectal bleeding persisting ≥ 6 wk without a change in bowel habits and without anal symptoms
Patients ≥ 60 yr with a change in bowel habits persisting ≥ 6 wk without rectal bleeding
Patients presenting with a right lower abdominal mass consistent with involvement of the large bowel
Patients presenting with a palpable rectal mass
Patients with unexplained iron deficiency anaemia (< 11 g/100 mL in men, < 10 g/100 mL in non-menstruating women)