Iodine-125 implantation in the management of localized prostatic carcinoma
Iodine-125 implantation has proved to be a safe and technically feasible means of delivering radiation therapy to the prostate. Local control of the prostatic neoplasm appears to be achieved in the majority of patients, although the criteria of tumor control leave open the question of whether or not the tumor has been locally destroyed by the treatment. Nevertheless, the local control rate, within the limitations of response definitions, implies either that implantation of I-125 has some effect on local tumor control or that the local growth of prostatic tumors is often extremely protracted. Failure of I-125 implantation appears to be related primarily to antecedent regional or undetected distant metastases. This technique is applicable to a far larger proportion of patients with localized prostatic cancer than is radical prostatectomy by virtue of its use in patients with stage B or small stage C lesions. However, external radiation therapy is clearly applicable to the largest patient population, since it may be used in patients with bulky stage C tumors who are unsuitable for implantation. Iodine-125 implantation has far less attendant morbidity when compared with other treatment modalities that are presently available and preserves the functional integrity of the pelvic organs. The ultimate role of I-125 implantation in the management of localized prostatic carcinoma is yet to be determined, but the I-125 technique has produced results that are comparable, stage for stage, to those noted for alternative measures of treatment within the limitations of available follow-up information. However, in the absence of control data, the relative contributions of the natural history of the disease and of the specific treatment to the results achieved remain uncertain.