Prevalence of gastrointestinal malignancy in iron deficiency without anaemia: A systematic review and meta-analysis

Background: Iron deficiency anaemia is associated with gastrointestinal (GI) malignancy and is an indication for GI investigations. However, the relevance of iron deficiency without anaemia (IDWA) and the underlying risks of GI malignancy are uncertain. Therefore, the aim of this study was to estimate the prevalence of GI malignancy in patients with IDWA overall and in clinically relevant subgroups. Methods: We searched MEDLINE and EMBASE for studies that reported on the prevalence or risk of GI malignancy in patients with confirmed IDWA. We performed a random effects meta-analysis of proportions and assessed statistical heterogeneity using the I-2 statistic. Results: A total of 1923 citations were screened and 5 studies (4 retrospective cohorts, 1 prospective cohort) comprising 3329 participants with IDWA were included in the meta-analysis. Overall pooled random-effects estimates for prevalence of GI malignancy in those with IDWA were low (0.38%, 95% CI 0.00%-1.84%, I2 = 87.7%). Older patients (2.58%, 95% CI 0.00%-8.77%); non-screening populations (2.45%, 95% CI 0.16%-6.39%) and men and post-menopausal women (0.90%, 95% CI 0.11%-3.23%) with IDWA were at increased risk of GI malignancy compared to younger patients (0.00%, 95% CI 0.00%-0.21%); screened populations (0.24%, 95% CI 0.00%-1.10%) and pre-menopausal women (0.00%, 95% CI 0.00%-1.05%). Conclusion: Overall, IDWA is associated with a low risk of GI malignancy. Older patients and non-screening populations are at elevated risk and require GI investigations. Those not in these subgroups have a lower risk of GI malignancy and may wish to be monitored following discussion of the risk and potential benefits of GI investigations.