Theranostics Against Cancer
A Personalized Medicine... Well Dosed
Benoit Galarneau Eng., M.Sc.A., MBA
Cancer is the insatiable evil of the century. According to the World Health Organization, it caused 8.8 million deaths in 2015. Nearly one in six deaths worldwide is due to this disease. Even worse, the number of new cases is expected to increase by about 70% over the next two decades. Doctors, researchers and scientists are multiplying their efforts and competing ingeniously to try to overcome it, or at least refine the means of detecting, diagnosing and treating it.
The new weapon against cancer is called theranostics, a contraction of the words "therapy" and "diagnostic". "It's the one-word expression of the combined activity and the same continuum of a diagnostic and therapeutic process for a patient," says Dr. François Lamoureux, Associate Professor of Clinical Medicine in Nuclear Medicine at the Faculty of Medicine, University of Montreal and President of the l’Association des médecins spécialistes en médecine nucléaire du Québec (Quebec Association of Medical Specialists in Nuclear Medicine).
The objective of the technique is to study the behavior of a tumor closely in order to choose the most appropriate treatment. It is therefore a question of mapping the cancer cells (thanks to functional imaging) and then targeting them with a localized treatment.
How Does it Work?
On their surface, cancer cells present various physiological targets, such as receptors, enzymes or proteins. The theranostic approach consists in targeting them specifically by targeting molecules (specific ligands) labeled with radioactive elements. These are intended for diagnosis, they emit radiation that can be visualized by imaging, or in therapy, it is to directly irradiate the tumor with a powerful radionuclide. Typically, it would be to use, for example, a tracer labeled with gallium 68 for diagnosis and then a therapeutic radionuclide such as lutetium 177.
Here we are in the long-awaited era of personalized medicine. "With the theranostic approach in cancer, one can more judiciously choose not only for a very specific patient the most suitable treatment – both at the level of molecules and doses –, but also apply innovative treatments", details the specialist. And since each treatment is specifically chosen for each patient, it avoids the mass treatments that could prove to be little or not effective.
The Right Dose
In addition to offering a personalized medicine, it must be ensured that it is as well dosed... And it is even more indispensable when using radioactive elements. While radioactivity offers patients significant benefits, it is important to avoid its deleterious consequences. For that, one must know the cumulative dose of radiation that is being received or has been received by a patient: their dosimetry.
In this connection, the European Atomic Energy Community (EAEC or Euratom) has legislated on exposure to ionizing radiation. Thus, Directive 2013/59/Euratom of December 5, 2013 is laying down basic safety standards for protection against the dangers from exposure to ionizing radiation for patients and professionals. In other words, when a doctor chooses a theranostic approach, he will have to calculate the adequate dose of radioactive elements that the patient will receive to minimize its adverse effects and focus on the cells to be eradicated.
Now it’s North America's turn to legislate to make this personalized medicine more precise.