The Use of Interstitial Radiation in the Treatment of Primary and Recurrent Carcinoma of the Uterine Cervix

Abstract

IN many clinics there is a tendency to standardize the treatment of cervical cancer so that a routine method of radiation is used for all patients. No single method is suitable for all individuals, but in most instances there are certain advantages to be gained if treatment is begun with external radiation (8). By that means the amount of infection in the lesion can be reduced, which, in turn, will lessen the local reaction from radium applied at a later date. A preliminary course of x-rays also facilitates radium treatment by producing some regression in the size of the primary lesion. However, if the percentage of cures is to be increased materially, it is essential to individualize both the roentgen and radium treatment of each patient to meet the requirements of the lesion in question, rather than to apply a single method to all patients with cervical cancer. In a previous publication (2) diagrams illustrating the distribution of roentgen radiation within the average female pelvis were given for different physical factors of radiation. In the treatment of carcinoma of the cervix it is essential that a large dose be given to the parametrium without over-radiating normal structures in other regions. A six-field technic (two on the anterior surface, two on the posterior, and one on each lateral aspect of the pelvis) was found to deliver the greatest amount of radiation to the parametrium without too great a percentage of the total dose falling upon the bladder and rectum. That arrangement of skin portals is suited to most patients with cervical cancer, but in every instance the attempt should be made to individualize the treatment. A different technic might be more practical for patients presenting a marked degree of involvement anterior or posterior to the cervix. There is general agreement that an intrauterine tandem containing radium will not control disease located at distances greater than 3 or 4 cm. from the cervical canal. In the attempt to increase the radius of effect from radium applied to the primary lesion, Healy (6) and others have devised various intra-vaginal applicators for use in conjunction with an intra-uterine tandem. In most patients, however, radium alone is inadequate for delivering a lethal dose to the entire tumor-bearing region. External radiation is essential in the attempt to treat adequately the disease located in outlying tumor-bearing areas, and in the deep lymphatics. The distribution of radiation for different methods of applying radium to the cervix has been shown diagrammatically by Lucas (10) and the author (1). While these diagrams show that radium alone is inadequate for most patients, they also illustrate the fact that a greater number of sources of radium distributed more widely throughout the uterus and vagina will, for specified doses, increase the minimum amount of radiation reaching the tumor, and decrease the risk of over-radiating some regions.