Cancer is diagnosed using one or more tests.
X-ray (radiological) appearances
A biopsy is the most important way of diagnosing cancer.
A biopsy is the removal of a piece of tissue, which can be examined under the microscope by a pathologist who is trained to recognise the appearance of cancer (and other diseases).
A biopsy can identify whether there is a primary or secondary cancer, or whether there is pre-cancer (carcinoma in-situ).
A biopsy can be obtained with a needle under local anaesthetic, by a minor operation under local or general anaesthetic or by a major operation.
Cytology is a collection of cells which can be examined under the microscope by a cytologist (pathologist) who is trained to recognise the appearance of cancer.
Cytology can identify whether cancer cells are present. On its own it cannot distinguish between cancer and pre-cancer (carcinoma – in-situ). It can sometimes tell the type of cancer.
Cytology samples are obtained from a smear test, from a needle taken from a lump or a fluid collection taken by needle, or from a washing of part of the lung.
Sometimes it is not feasible to obtain a biopsy from a patient, usually because taking it may be too dangerous, or not very helpful. In such cases, usually relating to the brain or lung, an X-ray or scan is used to diagnose cancer.
Blood tests on their own they are not able to diagnose cancer, but occasionally they may help to confirm the results of cytology and X-rays or scans.