What tests are performed to diagnose colorectal cancer?
- Physical exam and medical history
- Digital rectal exam (DRE)
- Proctoscopy: an office based exam of the rectum using a proctoscope, inserted into the rectum.
- Flexible sigmoidoscopy: the doctor puts a short, thin, flexible, lighted tube into your rectum, and checks for polyps or cancer inside the rectum and lower third of the colon.
- Colonoscopy: a procedure to look inside the rectum and colon for polyps (small pieces of bulging tissue), abnormal areas, or cancer. Polypectomy and biopsy of the lesion can be done during the procedure.
- Certain centres have the provision of doing CT colonography (virtual colonoscopy) but the disadvantage is that biopsies cannot be taken with this procedure
- Biopsy: the removal of cells or tissues so they can be viewed under a microscope to check for signs of cancer.
- Screening is done by DRE, stool test and sigmoidoscopy/colonoscopy
- Stool tests: there are two types of FOBT tests. Guaiac-Based Faecal Occult Blood Test (GFOBT) uses the chemical guaiac to detect blood in stool, while Faecal Immunochemical Test (FIT) uses antibodies to detect blood in the stool
- CEA assay are done to support the diagnosis and also to help in follow up and observing the response to treatment (prognostication)
What determines the prognosis (outcome) for colorectal cancer?
- The stage of the cancer (how far advanced the cancer is)?
- Which part of the large intestine has cancer occupied?
- Whether the bowel is blocked or has a hole in it?
- Whether all of the tumour can be removed by surgery?
- The patient’s general health and ability to tolerate different treatment regimens.
- Whether the cancer has just been diagnosed or has recurred (come back)?
How is colorectal cancer staged?
- CT scan can accurately detect the presence of most cancer cells that have spread outside of the rectum.
- PET scan
- MRI is one of the tests used for local staging. This will help determine if the tumour has spread through the wall of the rectum and if it has invaded nearby structures.
- Endoscopic Ultrasound (EUS): a procedure in which an endoscope or rigid probe is inserted into the body through the rectum.
Note: Any medical information published on this website is not intended as a substitute for informed medical advice and you should not take any action before consulting with a healthcare professional.
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