Identification and quantification of the clinical features of inflammatory bowel disease and colorectal cancer in patients under 50

Problem

Colorectal cancer in younger patients is often diagnosed after significant delay. It is not known if the symptoms are the same as in older patients. One possible way of accelerating diagnosis of bowel cancer in the young, is to consider it alongside inflammatory bowel disease (IBD - Crohn’s disease and ulcerative colitis) as both conditions share many of the same symptoms.

Approach

This was a case–control study using electronic primary-care records of UK patients aged<50 years. Cases with primary colorectal cancer or IBD were matched to controls on age, sex and practice. Putative features were identified in the year before diagnosis. Odds ratios (ORs) were calculated for these features using conditional logistic regression, and positive predictive values (PPVs) were calculated.

Findings

A total of 11239 cases and 26926 controls were studied. Eleven features were independently associated with colorectal cancer and/or IBD (all P<0.001): abdominal pain, OR 3.72 (95% confidence interval 3.27–4.22); change in bowel habit, 26.9 (18.94–39.19); diarrhoea, 8.93 (7.48–10.67); rectal bleeding, 41.69 (32.22–53.93); weight loss, 1.34 (1.23–1.46); low haemoglobin, 2.45 (2.01–2.98); low MCV, 2.56 (1.96–3.34); raised inflammatory markers, 5.22 (4.44–6.13); raised hepatic enzymes, 1.34 (1.14–1.57); raised white cell count, 1.50 (1.22–1.84); and thrombocytosis, 4.54 (3.49–5.92). The only PPV >5% in patients <50 years was for low haemoglobin with a change in bowel habit.

Consequences

Symptoms of colorectal cancer and inflammatory bowel disease are similar in younger patients presenting in primary care. Rectal bleeding and a change in bowel habit are strongly predictive of both colorectal cancer and inflammatory bowel disease, and can be used to identify patients meriting colonoscopy.