Backgound The number of patients with chronic gastrointestinal (GI) symptoms after cancer therapies which have a moderate or severe impact on quality of life is similar to the number diagnosed with inflammatory bowel disease annually. However, in contrast to patients with inflammatory bowel disease, most of these patients are not referred for gastroenterological assessment. Clinicians who do see these patients are often unaware of the benefits of targeted investigation (which differ from those required to exclude recurrent cancer), the range of available treatments and how the pathological processes underlying side effects of cancer treatment differ from those in benign GI disorders. This paper aims to help clinicians become aware of the problem and suggests ways in which the panoply of syndromes can be managed.

Methods A multidisciplinary literature review was performed to develop guidance to facilitate clinical management of GI side effects of cancer treatments.

Results Different pathological processes within the GI tract may produce identical symptoms. Optimal management requires appropriate investigations and coordinated multidisciplinary working. Lactose intolerance, small bowel bacterial overgrowth and bile acid malabsorption frequently develop during or after chemotherapy. Toxin-negative Clostridium difficile and cytomegalovirus infection may be fulminant in immunosuppressed patients and require rapid diagnosis and treatment. Hepatic side effects include reactivation of viral hepatitis, sinusoidal obstruction syndrome, steatosis and steatohepatitis. Anticancer biological agents have multiple interactions with conventional drugs. Colonoscopy is contraindicated in neutropenic enterocolitis but endoscopy may be life-saving in other patients with GI bleeding. After cancer treatment, simple questions can identify patients who need referral for specialist management of GI symptoms. Other troublesome pelvic problems (eg, urinary, sexual, nutritional) are frequent and may also require specialist input. The largest group of patients affected by chronic GI symptoms are those who have been treated with pelvic radiotherapy. Their complex symptoms, often caused by more than one diagnosis, need systematic investigation by gastroenterologists when empirical treatments fail. All endoscopic and surgical interventions after radiotherapy are potentially hazardous as radiotherapy may induce significant local ischaemia. The best current evidence for effective treatment of radiation-induced GI bleeding is with sucralfate enemas and hyperbaric oxygen therapy.

Conclusions All cancer units must develop simple methods to identify the many patients who need help and establish routine referral pathways to specialist gastroenterologists where patients can receive safe and effective treatment. Early contact with oncologists and/or specialist surgeons with input from the patient's family and friends often helps the gastroenterologist to refine management strategies. Increased training in the late effects of cancer treatment is required.