Such metastases may in themselves give rise to further spread of the tumor. Although the primary tumor may be eradicated by surgery or radiotherapy, the metastases will remain unaffected. It is the metastatic tumor that ultimately causes treatment failure and kills the patient. To the clinician treating patients with malignant tumors it is clearly of great importance to establish whether or not an individual patient has metastatic disease. This is true, both at the time of diagnosis when treatment is being planned, and also afterwards when the patient is being regularly reviewed by his physician.
Many investigations are currently available to help in the follow up of cancer patients.
Similarly, nuclear medicine has contributed greatly to the management of patients with malignant disease by the development of techniques such as isotope bone and liver scanning. Here a radioactive material is given which is taken up by the organ and areas of abnormality due to the presence of tumor will show up either as increased or decreased uptake on a scan of radioactivity distribution in the patients. These scans detect areas of abnormality with great precision and reproducibility. The limitation with all these methods is that the abnormalities detected are non-specific. Similar X-ray or scan appearances may be produced by tumors, abscesses, cysts and certain congenital malformations.