Introduction to Theranostics
Theranostics is a field of medicine that refers to a combination of diagnostic imaging and therapy to treat various types of cancers. Theranostics = Therapy + Diagnostics. Patients are imaged and depending on the tumour size and spread, are identified for therapy. The therapy is given by localized radiation delivered only to the diseased region, reducing the impact on surrounding healthy cells.
How does it work?
- Radioactive compound is attached to a linking molecule that is bound to the binding molecule, which attaches to the cancer cell.
- Theranostics works by acquiring diagnostic images and delivering therapy by utilizing gamma radiation and beta radiation respectively.
- Gamma radiation is of higher energy and can penetrate the tissues to be detected outside the body. Radiotracers that emit gamma radiation are used for diagnostic imaging. Beta radiation is of medium energy and can penetrate short distances inside the body (reduces effect on nearby cells). Therefore, radiotracers that emit beta radiation are used for delivering therapy. Higher energy beta radiation may be used for tumours that are large in size.
- Commonly used diagnostic radiotracer: technetium-99m (99mTc), Iodine-123 (123I)
- Commonly used therapeutic radiotracer: Lutetium-177 (177Lu), Yttrium-90 (90Y)
Theranostics – personalized medicine?
Theranostics involves diagnostic imaging, therapy planning, classification of tumour, evaluating the stage of tumour and frequent follow-ups during therapy. Since the radiotracer dose given to patient is dependent on location, size, extent of tumour, it can be considered as personalized medication. The optimization of therapy reduces side effects and reduces the chances of healthy cells getting affected.
Theranostics is currently used very much for neuro-endocrine tumours. Availability of radiotracers at affordable cost has been a barrier in implementing this technology widely. Development of alternative radiotracers that serve the same purpose may be a solution to the above issue. The same will help in making this technology available to everyone and different tumours. Diagnostic imaging (PET/SPECT) is already dominating nuclear medicine. It will not take Theranostics much time to become an equal contributor in nuclear medicine. Theranostics is an exciting field one capable of developing rapidly in the near future.
Image source – https://goo.gl/mTsKmG