Optimizing radiation parameters for cervical cancer.

The treatment of cervical cancer has become increasingly sophisticated with evidence-based guidelines generated from randomized trials directing combined modality programs. The radiotherapeutic guidelines have been derived largely from single institutional experiences coupled with data from the Patterns of Care Studies. The design of external-beam fields has improved because of a better understanding of the anatomy of the cervix, uterus, parametrium, and draining lymph nodes from surgical, lymphangiogram, computed tomography scan, and magnetic resonance imaging series. An improvement in survival and local control with dose intensity (a reduction in overall treatment time and increase in overall dose) has been shown for cervical cancer, especially for locally advanced disease, and these series are highlighted. The use of intracavitary radiation, which is technically accurate, dramatically improves outcome and allows for dose intensity. Alternative brachytherapy techniques, such as high-dose-rate, and interstitial, are discussed. Ways to improve the therapeutic ratio for radiation, including biological factors, are reviewed. More research is necessary to understand the complex dose distribution of external-beam and intracavitary brachytherapy and its relationship to tumor control.