Common tests for cancer

• Blood tests, typically to check for anaemia (lack of red blood cells) or too few or too many white blood cells, and to assess liver and kidney function.
• Other bodily fluids may also be examined. Patients with suspected lung cancer, for example, may have their sputum (saliva) sent for analysis.
• Scanning – magnetic resonance imaging (MRI), computer tomography (CT) and, most recently, positron emission tomography (PET) have added to the diagnostic tools available to doctors over the last decade or so. CT is good for detail. MRI is more versatile. PET gives information about cell function as well as structure. For all these tests the patient lies down in a cylindrical scanner after, in some cases, drinking or being injected with a contrast medium that shows up during the procedure. The procedure doesn't take long, is totally painless and involves the patient in less exposure to radiation than an X-ray.
• Ultrasound scanning – this involves passing a soundwave-emitting transducer (which looks like a large stethoscope) over the skin. It's far cheaper and easier to do than MRI, CT or PET, and is still commonly used in, for example, testing for testicular cancer.
• Endoscopy or colonoscopy – fibre-optic internal viewing tubes called endoscopes can be inserted into the mouth or backside to enable closer examination of, for example, the stomach, prostate gland or bowel.
• The various tests will generally culminate in a biopsy in which part of the tumour is cut out and examined. (Fine-needle biopsy is a less invasive option – a needle is stuck into the tumour and a small amount of fluid is withdrawn for analysis.) A biopsy enables a pathologist to see directly how the cells relate to each other, and is the most reliable way of diagnosing cancer.