A history of photodynamic therapy.

The origins of light as a therapy in medicine and surgery are traced from antiquity to the modern day. Phototherapy began in ancient Greece, Egypt and India but disappeared for many centuries, only being rediscovered by Western civilization at the beginning of the twentieth century through the Dane, Niels Finsen, and the Germans Oscar Raab and Herman von Tappeiner. The discovery of the tumour-localizing ability of haematoporphyrin, together with its phototoxic effect on tumour cells led to the development of photodynamic therapy, a promising tool in modern cancer treatment.