Theodore S. Lawrence, MD, PhD

Chemotherapeutic agents that are highly responsive to ionizing radiationand enhance the effectiveness of radiation treatment are termedradiation sensitizers. Radiation sensitizers act in a number of ways tomake cancer cells more susceptible to death by radiation than surroundingnormal cells, and several such compounds are now available forthe treatment of solid tumors. This review discusses the biology thatunderlies chemotherapy and radiation interactions for oneradiosensitizerSMQ-8212-SMQgemcitabine (Gemzar). It also provides a brief assessmentof how to modify treatment regimens for various cancers to maximizethe radiosensitization potential of gemcitabine in order to furtherincrease efficacy. Newer molecularly targeted agents and their antitumorpotential as monotherapy or in combination with radiation arealso reviewed.

Gemcitabine is a potent radiosensitizer in both laboratory studies and in the clinic. Initial laboratory studies showed that gemcitabine radiosensitizes a wide variety of rodent and human tumor cells in culture. Maximum