Radiation sensitizers and targeted therapies.

Chemotherapeutic agents that are highly responsive to ionizing radiation and enhance the effectiveness of radiation treatment are termed radiation sensitizers. Radiation sensitizers act in a number of ways to make cancer cells more susceptible to death by radiation than surrounding normal cells, and several such compounds are now available for the treatment of solid tumors. This review discusses the biology that underlies chemotherapy and radiation interactions for one radiosensitizer--gemcitabine (Gemzar). It also provides a brief assessment of how to modify treatment regimens for various cancers to maximize the radiosensitization potential of gemcitabine in order to further increase efficacy. Newer molecularly targeted agents and their antitumor potential as monotherapy or in combination with radiation are also reviewed.