Evidence for improved prognosis of colorectal cancer diagnosed following the detection of iron deficiency anaemia

Abstract

Iron deficiency anaemia (IDA) is common in colorectal cancer (CRC), especially, in right-sided CRC which is known to have an overall worse prognosis. The associations between diagnostic pathway (Bowel Cancer Screening Programme (BCSP), IDA, symptomatic) and tumour side/stage was assessed using logistic regression models in 1138 CRC cases presenting during 2010-2016 at a single secondary-care centre in the UK. In the IDA sub-group, the relationship between CRC stage and the event of having a blood count prior to CRC diagnosis was examined using Bayesian parametric survival model. IDA was found as the only significant predictor of right-sided CRC (OR 10.61, 95% CI 7.02-16.52). Early-stage CRC was associated with both the IDA (OR 1.65, 95% CI 1.18-2.29) and BCSP pathway (OR 2.42, 95% CI 1.75-3.37). At any age, the risk of detecting CRC at late-stage was higher in those without a previous blood count check (hazard ratio 1.53, 95% credibility interval 1.08-2.14). The findings of this retrospective observational study suggest a benefit from diagnosing CRC through the detection of IDA, and warrant further research into the prognosis benefit of systematic approach to blood count monitoring of the at-risk population.

Figure 1

The distribution of tumour stage by presentation pathway.

Figure 2

The cumulative percentage prevalence of blood count checks in the 12, 24 and 36 months prior to the diagnosis of CRC in the IDA group, sub-divided according to the tumour stage (early/late) and Hb result (g/l).

Figure 3

Posterior survival distributions for the IDA group, showing (a) the baseline survival probability at any given time S(t), with dashed lines representing the credibility interval, and (b) the survival probabilities for sub-groups categorised by whether a blood count was done in the two years prior to the presentation window.