Introduction to GI cancer
This page provides an overview of gastrointestinal (GI) cancer, the associated disease burden and clinical considerations relating to the most common GI tumour types.
GI tract cancer is a collective term used to describe cancers that affect the digestive system. Worldwide, the most commonly diagnosed GI cancers include: colorectal cancer (CRC); gastric cancer; liver cancers (e.g. hepatocellular carcinoma [HCC]); oesophageal cancer; and pancreatic cancer.1
Less common GI cancers include those affecting the anus, appendix, bile duct, gallbladder and small intestine,2,3 as well as GI neuroendocrine tumours (NETs) and stromal tumours (GISTs), which are characterised by their cell type of origin rather than their location within the GI tract.4,5
GI cancers are responsible for more cancer-related deaths than any other type of cancer.6 In 2018, they accounted for an estimated 3.4 million deaths worldwide, with a further 4.8 million new cases diagnosed in the same year.6
Common GI cancers: global incidence and mortality6
*Global data, both sexes, all ages; **CRC, gastric cancer, oesophageal cancer, pancreatic cancer, liver cancer.
CRC, colorectal cancer; GI, gastrointestinal.
Common types of GI cancer
CRC is the most common type of GI cancer, with 1.85 million new cases diagnosed worldwide in 2018, making it the third most common of all organ cancers, after lung and breast.6
In the same year, gastric (or stomach) and oesophageal cancers were ranked the fifth and seventh most commonly diagnosed cancers (respectively), with 1.03 million new cases of gastric cancer and 0.6 million new cases of oesophageal cancer worldwide.6
Rank order of incident cancer cases in 20186
CRC, colorectal cancer; GI, gastrointestinal.
Common GI cancers ‘at a glance’
CRC occurs when a growth in the lining of the large intestine (colon), or at its end (rectum), becomes cancerous. It is one of the leading causes of cancer-related deaths in men and women, worldwide.6
Approximately 25% of patients with CRC present with metastases at the time of initial diagnosis, and almost a half go on to develop metastases at some point, contributing to its high mortality rate.7
Location of the colon and rectum within the digestive system
The prevalence of gastric (or stomach) cancer varies significantly around the world.6,13 The highest rates are seen in Eastern Asia, Eastern Europe and South America, and the lowest in North America and Western Europe.13 Over the last 60 years, there has been a gradual decline in new cases across North America and Western Europe and, more recently, in higher-prevalence regions.13
Location of the stomach within the digestive system
Liver cancer is the third most common GI cancer.6 There are two major subtypes: HCC and intrahepatic bile duct cancer. HCC is the more common of the two, with rates increasing globally for the last 20 years (and predicted to continue to increase until 2030).14
Location of the liver within the digestive system
Common symptoms include: pain, fatigue, weight loss and obstructive syndromes, such as ascites and jaundice15
Risk factors include: chronic liver disease, liver cirrhosis, hepatitis infection14
Staging and management: several staging systems have been developed, including the Barcelona Clinic Liver Cancer (BCLC) system. BCLC staging links tumour stage, liver function, cancer-related symptoms and performance status (PS) to an evidence-based treatment algorithm:14
There are two main subtypes of oesophageal cancer – squamous cell carcinoma (SCC) and adenocarcinoma. SCC occurs more frequently in the upper and middle parts of the oesophageal tract, while adenocarcinoma usually occurs in the lower part of the oesophagus, near the junction with the stomach.16
Although SCC accounts for approximately 90% of cases of oesophageal cancer, adenocarcinoma is associated with a higher mortality rate. Indeed, adenocarcinoma mortality rates have now surpassed those of SCC in some countries.16,17
Location of the oesophagus within the digestive system
Uncommon tumours at a glance
GI NETS account for a very small proportion of newly diagnosed malignancies (approximately 0.5%), but 62–67% of NETs occur in the GI tract.18
GI NETs can arise from the pancreas or neuroendocrine cells distributed throughout the mucosa and submucosa of the GI tract. GI NETs comprise a heterogeneous group of tumours that can present with a variety of clinical symptoms.19 The risk factors are not well characterised, but multiple endocrine neoplasia type 1 syndrome is implicated, and genetic and familial associations have been observed.18
Neuroendocrine neoplasms are broadly divided into two groups on the basis of clinical behaviour, histology and proliferation rate:18
Treatment and prognosis depends on the grade of differentiation and the stage of the tumour at the time of presentation;19 12–22% are metastatic at time of presentation.18 Treatment typically includes surgical resection in low-grade tumours and somatostatin analogues and/or interferon-α in patients with unresectable, symptomatic disease.18
GISTs account for approximately 1% of all GI tumours, but they are the most common mesenchymal tumours of the GI tract.5 They are thought to grow from specialised interstitial cells of Cajal (ICCs) that function as pacemaker-like intermediates between the GI autonomic nervous system and smooth muscle cells, regulating GI motility and autonomic nerve function.5,20
GISTs may be either malignant or benign and can occur anywhere in or near the GI tract; they appear most often in the stomach (60%) or small intestine (30%). They are typically diagnosed in adults aged 40–70 years.5,20
Some people with GISTs may experience pain or swelling in the abdomen, nausea, vomiting, loss of appetite or weight loss. Anaemia, black and tarry stools and vomiting of blood can also occur in cases where GISTs cause GI bleeding.20 A family history of GISTs is generally associated with more symptomatic disease and multiple (rather than single, ‘sporadic’) tumours.
The formation of GISTs is most commonly associated with mutations in the tyrosine-protein kinase KIT gene (approximately 80% of cases) and the platelet-derived growth factor receptor alpha gene (PDFGRA; approximately 10% of cases).20
Treatment may involve surgery and/or use of tyrosine kinase inhibitors (TKIs), depending on the extent of disease and TKI sensitivity.5
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Pourhoseingholi MA, et al. Gastro Hepat Bed to Bench 2015;8(1):19.
GI Cancer Alliance. GI Cancers. http://www.gicancersalliance.org/gi-cancers (Accessed: September 2019).
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National Cancer Institute. Gastrointestinal Stromal Tumors Treatment (PDQ®)–Health Professional Version. https://www.cancer.gov/types/soft-tissue-sarcoma/hp/gist-treatment-pdq (Accessed: September 2019).
International Agency for Research on Cancer (IARC). https://gco.iarc.fr/today/home (Accessed: September 2019).
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U.S. National Library of Medicine. Genetics Home Reference: Gastrointestinal stromal tumor. https://ghr.nlm.nih.gov/condition/gastrointestinal-stromal-tumor#resources (Accessed: September 2019).
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Page last updated: September 2019
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