Prostate specific antigen-monitored combination radiotherapy for patients with prostate cancer. I-125 implant followed by external-beam radiation

Abstract

Background. Because results of retropubic I‐125 implantation for prostate cancer have been poor, external beam radiation was added postimplant. Serum prostate specific antigen (PSA) was used to assess this approach of combined irradiation. Methods. Two hundred and thirty‐nine patients with clinical Stage T1 or T2 but surgically node‐negative prostate cancer were treated. Results were monitored by serial serum PSA evaluation. Positive clinical findings or a rising PSA level defined recurrent disease. Results. With a median follow‐up of 45 months (range, 24‐120 months), the Kaplan‐Meier projected disease free survival rate was 74% at 5 years and 66% at 10 years. Overall at a 60‐month minimum follow‐up, 77% of patients had a PSA of 0.5 ng/ml or less. This nadir level is highly predictive of a long term disease free survival, significantly better than pretreatment PSA, grade, or clinical Stage T1 or T2. Conclusions. The PSA‐monitored disease free survival rate after combination irradiation appears comparable with that after radical prostatectomy and perhaps superior to that after external‐beam radiation. This effect was achieved even though lower‐than‐usual doses of radiation from both sources were administered. The combination of an I‐125 implant followed by external‐beam radiation produces high doses within the prostate and, to a lesser extent, in the periprostatic tissue. Additive and synergistic effects from simultaneous irradiation may be responsible for these results.

Modern prostate brachytherapy

“…Some consider that external beam therapy is a necessary treatment component for patients with any stage or grade of prostate carcinoma who are treated with brachytherapy. 15,16 Although the published results from those studies were good, the follow-up was relatively short, and survival was projected by using actuarial methods rather than observation, which was used in our study. Conversely, Grado et al, 2 reporting 5-year actuarial results on a series of 490 patients who were treated with brachytherapy and brachytherapy combined with external beam radiation therapy, found no significant benefit by adding external beam radiation.…”

Combining radiation therapy with interstitial radiation-inducible TNF-α expression for locoregional cancer treatment

“…[1][2][3] The effectiveness of radiation therapy is well documented by comparisons with radical prostatectomy; 4 however, with the advent of the test for prostate-specific antigen, it has become evident that treatment failure may occur more frequently than previously appreciated following both radiation therapy and surgery. [5][6][7][8] Furthermore, post-radiation therapy biopsies have revealed more locally persistent disease than expected and the local failures following radiation therapy eventually result in higher metastatic rates. 9,10 Therefore, improved local control of prostate cancer predicts reduced local sequelae (uncontrolled pelvic disease) and improved survival (decreased metastatic disease).…”

“…4 Implanted radioactive sources deliver highly localized radiation doses. [3][4][5][6][7][8][9][10][11] Owing to the favorable 'inverse square' distance effects from radiation sources, much of the bladder and rectum can be spared major damage with this technique. This commonly used procedure results in long-term control or 'cure' for many patients.…”

Prostate specific antigen levels in the follow up of localised prostate cancer: how does radiotherapy compare to radical prostatectomy?

“…After treatment the median time required to reach the nadir in PSA levels is 18 months. 3 A rising PSA after irradiation is associated with progression to metastatic disease. 4 After radical prostatectomy, potential complete remission is associated with undectable levels of PSA.…”