Project Description

Photodynamic therapy is a technique that has been adopted in several countries and has become a reality in Brazil in the treatment of non-melanoma skin cancer. This development has been possible thanks to the scientific work carried out by several Brazilian researchers, including the members of the Optics and Photonics Research Center financed by the Fundação de Amparo a Pesquisa do Estado de São Paulo (CePOF/FAPESP). This therapy involves three main components: a light-activated molecule called a photosensitizer, a visible light source, and molecular oxygen that together cause cancer cells to die. This technique, however, has a limitation, which is the low penetration of light in thicker skin tumors.

Among the forms of energy delivery in living tissues, therapeutic ultrasound has been shown to be a source of mechanical excitation of molecules that allows the activation of somnosensitizing medications (which make the tissue sensitive to ultrasound) in greater depth, due to its good penetration into the body. biological tissue and cell membrane sonoporation capacity (ie, opening small “holes” in the membrane). Therefore, unlike diagnostic ultrasound (which does not harm tissues), therapeutic ultrasound combined with these medications generates cell death according to its frequency and intensity.

The technique that uses ultrasound to activate molecules is known as sonodynamic therapy, and the combination of it with photodynamic therapy is known as sonophotodynamic therapy. The combined use of ultrasound and light, without an external sensitizing agent, has already been shown to be very efficient in relieving the symptoms of fibromyalgia and Parkinson's disease, and it is expected that with these associated medications it can bring other benefits in the treatment of diseases.

Light and ultrasound are two types of wave, light being called an electromagnetic wave, while ultrasound is called a mechanical wave. The ultrasound has that name because it is a type of sound wave, but that the human being cannot hear. The energy that the two carry propagates in different ways, and has different effects on living tissues.

Because of this, the effects of one and the other energy are associated in order to increase the treatment range in terms of depth. The combined use of light and ultrasound will more efficiently treat thicker skin lesions, for example. Thus, we are understanding the basic mechanisms of the joint action of light and ultrasound through several experiments, including animal tests.

Techniques such as Sonophotodynamic Therapy may contribute significantly to the improvement of treatments for these types of tumor. This mixed technique combines two modalities of therapy with minimal side effects, unlike approaches such as radiotherapy or chemotherapy – which in some cases could be avoided. The success of this and other research in this area can bring real benefits to patients.