Evaluation of the time interval between external irradiation and intracavitary curietherapy in carcinoma of the uterine cervix: influence on curability.

Abstract

Radiotherapy, generally accepted as the treatment of choice for invasive carcinoma of the uterine cervix, is administered differently at various cancer centers. No universal criteria exist for determining which cases are best handled by curietherapy alone, combined external irradiation and curietherapy, or external irradiation alone. Furthermore, there is disagreement in respect to timing of the application of radioactive sources and whether this should precede the external irradiation or vice versa. The results from different radiotherapy technics are comparable in the early stages of the disease but vary in the advanced cases; the best survival results have been reported from centers where external irradiation is used intensively for advanced stages (1, 2, 4). Paterson (5), in a clinical trial, demonstrated that external pelvic irradiation followed by intracavitary radium for carcinoma of the uterine cervix gave better results than when the curietherapy preceded the external treatment. Most of the patients, particularly those in advanced stages of the disease, benefit considerably from preliminary external irradiation of the whole pelvis. The rationale for this technic is that it helps to reduce bulky tumors into a more central mass more effectively handled by the intracavitary curietherapy. An additional theoretical advantage is the reduction of anoxia of tumor tissue that may occur when the neoplasm decreases its size. At our department we have always preferred to use external irradiation prior to the intracavitary application of radium or an equivalent radioactive source (Co60 or Cs137). We have also preferred to undertake the intracavitary application as soon as the external radiotherapy course has been completed. At times there has been a delay of one or more weeks between the end of external irradiation and the intracavitary curietherapy. The reasons for this delay have included scarcity of radioactive sources, excessive normal tissue reaction to the external irradiation (such as vesical or rectal symptoms and occasionally skin reactions), medical contraindications to anesthesia, etc. We have always considered that an interval exceeding one week between external irradiation and the intracavitary therapy may be detrimental to the patient in terms of curability; this fact was also pointed out to us by Dr. Juan A. del Regato (3), while visiting our department. The deliberate interruption of the radiation therapy treatment course (“split-course technic”), however, has been advocated by some workers (6, 7). It has been claimed that a rest period in the treatment course enhances healing of the normal tissues without a corresponding degree of recovery of the tumor cells. Rest periods of two to three weeks are common, but Sambrook has employed periods as long as four to six weeks.