[Interaction of radiotherapy and new agents with molecular targets]

Radiochemotherapy represents one of the greatest achievements in cancer treatment in recent decades, although it involves significant toxicity for patients. Research developed recently in the molecular biology of cancer has enabled understanding of the genetic and molecular changes that determine malign cellular transformation, which has led to the identification of key molecules, converting them into molecular targets that have led to a revolution in radiobiological concepts of cellular response to radiations and radioresistance. The new agents against molecular targets possess greater specificity and less adverse effects, making them more attractive than chemotherapy for combination with radiotherapy. They can act by inhibiting intracellular transduction signals, modulating the cellular cycle, apoptosis or inhibiting angiogenesis. The effect of radiotherapy can be strengthened through inhibition of cellular repopulation, improvement of tumour oxygenation, redistribution of the cellular cycle, inhibition of invasion and metastasis, and increase of radiosensitivity. The available data support its efficacy and applicability in preclinical and clinical studies in different tumour models and open up a promising path in cancer treatment.