ABSTRACT
Clinical reports of the treatment of many types of malignancies (including head and neck, ovarian, cervical, and non-small cell lung cancer) suggest that tumors initially resistant to chemotherapy, or that become resistant after treatment with chemotherapy, are more likely to be resistant to radiation (1-9). With the frequent and increasing use of combined-modality therapy in clinical practice, an understanding of possible cross-resistance between chemotherapy and radiation is essential. This chapter will focus on (1) identifying the clinical problem of radiation resistance in chemotherapyresistant tumors; (2) reviewing the proposed mechanisms of radiation resistance; and (3) analyzing current research that may provide further insight into how cells respond and possibly become resistant to radiation.
