Predominant parameters in the planning of radiation therapy of carcinoma of the cervix.

The radiobiological parameters at the basis of radiation are: randomness of cell killing by irradiation, hypoxia and reoxygenation, does response curves, relationship of histology and radiosensitivity, doses necessary to control sub-clinical disease and gross tumor, and the rationale for combining irradiation and surgery. The volume of cancer is the determining factor in treatment planning. Since there is no correlation between the volume of the tumor and 1971 FIGO staging, staging should not be used in treatment planning but instead the volume and extent of the tumor. For the "barrel-shaped" lesions originating in the endocervix, a simple extrafascial hysterectomy is very effective after somewhat diminished irradiation. Great interest has been given to irradiating not only the pelvic wall but also the common iliac and/or paraaortic lymphatics. Since the volume of tissues irradiated to high doses of external irradiation is a limiting factor, with fields extended to L4 or T12, the total external irradiation dose cannot exceed 4,500 rad.