Colorectal cancer (CRC) can be diagnosed after the onset of symptoms or through screening. Symptoms from the local tumour may be rectal bleeding, abdominal pain and a change in bowel habits. Abdominal distension, nausea and vomiting may also be symptoms resulting from obstruction. An iron deficiency anaemia can be an indicator of colorectal cancer.
A screening programme for colorectal cancer in the Netherlands started in 2014, inviting all persons aged between 55 and 75 for an immunohistochemic fecal occult blood test (iFOBT) every two years.
After a positive iFOBT, participants receive the advice to undergo a colonoscopy. Patients with an increased risk of CRC have an indication for surveillance colonoscopy and do not participate in the screening programme. This includes patients with familiar CRC, a history of adenomas or CRC, or inflammatory bowel disease (IBD).
The diagnosis is based on the histologic confirmation of a biopsy that is obtained via a colonoscopy. The vast majority of colorectal cancer concerns carcinomas, originating from adenomas or from ‘flat / invisible’ dysplasia occurring in IBD. Other histologic types, such as neuroendocrine tumours or lymphomas, are rare. The Tumour, Node and Metastasis (TNM) staging system is the preferred staging system for colorectal cancer. For localised colon cancer, surgery is the only curative treatment. Treatment and prognosis depend on the local and distant extent of the disease. Other treatment options for colorectal cancer may include chemotherapy and radiotherapy.