Radiotherapy: killing with complement

Radiation therapy has been used for more than 100 years to treat human disease with some of the first applications to cancers in the 1890s. Radiotherapy delivers ionizing radiation to target tissues leading to fragmentation and ionization of biomolecules, water, oxygen and other chemicals that generate reactive oxygen species (ROS). Direct and indirect ROS-mediated damage to DNA, membranes, proteins and other cellular components lead to cell death. Cancer tissues are more sensitive to this damage. The exact mechanism and mode of cell death, and the basis for selective cancer toxicity are still areas of active investigation.