Safe investigation of isolated change in bowel habit with a flexible sigmoidoscopy? A systematic review and meta-analysis.

Introduction: Public awareness campaigns have led to increasing referrals of patients to colorectal surgery for possible cancer. Change in bowel habit, is traditionally described as a symptom of a left sided bowel cancer. If this is the case in practice, it raises the potentially attractive option of investigating such patients with flexible sigmoidoscopy only. This study sought to systematically review the literature describing tumour location of patients with bowel cancer presenting with left-sided symptoms to establish the safety of potential investigation of these patients with flexible sigmoidoscopy alone.
Methods: A systematic review of studies reporting both the presenting symptoms of patients with bowel cancer and the location of their cancer in the bowel was prospectively registered (CRD42017072492). MEDLINE, EMBASE and CENTRAL were searched with no date or language restriction.
Results: Seven studies were included. Isolated change in bowel habit (with or without rectal bleeding) was a presenting symptom of 73% (95% CI 41-96%, I2 = 99%) of left-sided cancers but also in 13% (95% CI 2-30%, I2 = 96%) of right-sided cancers. In all patients with cancer who presented with isolated change in bowel habit (with or without rectal bleeding), the cancer was right sided in 8% (95% CI 4-12%, I2 = 69%).
Conclusions: There is a higher than expected risk that if a cancer is diagnosed in a patient presenting with either an isolated change in bowel habit or a combination of change in bowel habit with rectal bleeding, the cancer may be right sided.