Cancerous tumours of the colon or rectum
A cancerous tumour of the colon or rectum can grow into nearby tissue and destroy it. The tumour can also spread (metastasize) to other parts of the body. Cancerous tumours are also called malignant tumours.
Adenocarcinoma
Adenocarcinoma is the most common type of colorectal cancer. Adenocarcinoma starts in cells that make mucus along the inner lining of the colon or rectum (called the mucosa). Mucus helps stool (feces) move through the colon and rectum.
Uncommon subtypes of adenocarcinoma, such as mucinous adenocarcinoma and signet ring cell carcinoma, are named based on how they look under a microscope.
Rare colorectal tumours
The following cancerous tumours of the colon or rectum are rare:
- squamous cell carcinoma, which is treated like anal cancer
- neuroendocrine tumour (NET)
- soft tissue sarcoma, such as leiomyosarcoma
- gastrointestinal stromal tumour (GIST)
- non-Hodgkin lymphoma, such as MALT lymphoma
- melanoma
These rare tumours are usually treated differently than adenocarcinomas. If you have one of these types of cancer, your healthcare team will discuss the treatment options and decide what will work best for you.