Tracking cancer

activity (in other words, while it is affixing the glucose), which considerably increases the probability of cancer», the doctor stresses.

Does this mean that radiology is becoming superfluous in the field of oncology? «Not at all, these are complementary tools», says Dr Charles Steiner. «Thanks to the technical evolution, these two techniques are frequently being combined (SPECT/CT or (PET/CT), which offers a very clear view of the matter at hand.»

These data allow us in particular to determine the stage of the illness. «One can diagnose the presence of tumour cells in the whole body in a single examination. This has a direct influence on the treatment, which will be decided upon within the framework of a multidisciplinary oncological discussion bringing together various specialists, in oncology, haematology, radiology, nuclear medicine, radio-therapy and pathology.»

Furthermore, nuclear medicine plays a fundamental role in the course of treatment. «It lets us determine quickly whether chemotherapy will have an effect or not. It takes a certain amount of time for a tumour to change its anatomical features, for example it's volume, so looking at its metabolism will give us an answer.» It is also being used increasingly in the planning of radiotherapy.

Nuclear medicine is also known at therapeutic level. Some radio-pharmaceuticals that are highly radioactive do have the capacity to destroy cancerous cells in which they nest. The best-known example is cancer of the thyroid, which is treated with radioactive iodine. Nuclear medicine has also taken advantage of new treatments using radioactive antibodies. «This permits treatments with the advantage that one can verify the selective location inside the tumour thanks to imaging.» Another leap forward seems underway.Grangettes

Nuclear medicine allows detection and localisation of tumours
that are still invisible to radiology. It's a very useful technology
for diagnosing an illness and following its evolution, especially
the effectiveness of the therapy.

Tracking cancer


uclear medicine is in the process of transforming the life of oncologists», says Dr Charles Steiner, the doctor in charge of the Institute for Nuclear Medicine at the Clinique des Grangettes, and an associate doctor at the HUG. Indeed, this imaging technology can detect some tumours at an initial stage and/or the dissemination of tumour cells (for example, in lymphatic ganglions) before they can provoke a deformation of their normal architecture, which is then detected by radiology.

In concrete terms, nuclear medicine is an imaging technology that is described as functional or molecular. In other words, it permits visualization of cellular functions – i.e., the life of the cells – by means of biochemical probes: radio-pharmaceuticals. Explanation: «We inject glucose marked with radioactive fluorine-18, for example. It affixes itself to cancerous cells and allows us not only to detect them at an early stage, but also to locate them very precisely», says Dr Charles Steiner.

Indeed, one of the traits of cancerous cells is their need for a great quantity of energy to multiply. As a result, a product based on glucose (an energetic substance) will

concentrate in the cells, thereby signalling abnormal activity. After a certain delay, the imaging can be done with a special camera allowing to locate the cells in the human body. These images are known as scintigraphs, planar or tomographic images (SPECT and PET). As for the doses of radioactivity injected, they are no greater than those involved in conventional radiology, they are also justified, limited and optimised so as not to additionally burden the health of the patient.

Knowing the life of the tumour

While radiology shows the anatomy of the tumour's mass (the volume and its relation with neighbouring organs), nuclear medicine images cellular activity. This is important, since a mass can represent something inactive (like a scar) or, contrariwise, an active process (a tumour, for instance). An example: «With the scanner (CT) one can detect and localize precisely a mass that is in a lung and that is not necessarily cancerous. With PET technology, on the other hand, you can reveal an increase in cellular