Percutaneous seed implantation for localized prostate cancer

Nicolas A. Muruve, M.D., FRCS(C)

Prostate cancer is the second leading cause of cancer deaths for men in the United States. Last year 317,100 men were expected to be diagnosed with the disease and 41,400 men were expected to die of prostate cancer.

Radical prostatectomy remains the gold standard for treating localized prostate cancer. But this modality is best suited for patients with a life expectancy greater than 10 years and disease favorable to local therapy. However, because of its potential complications, many patients are reluctant to proceed with surgery and seek other modalities.

Recently, brachy-therapy with palladium103 or iodine125 radioactive seeds has undergone a revival. Newer techniques for seed placement have improved the effectiveness of this therapy, making it an option for individuals who are either not surgical candidates or do not wish to risk the potential complications of surgery.

Seed placement
During the 1970s and early 1980s, seed implantation was performed blindly through an open incision in association with a pelvic lymph node dissection. Since results of the open-incision technique were less favorable than surgery or external beam therapy, it was abandoned.

The development of transrectal ultrasound made radioactive seed placement more accurate, thus providing more even dosing throughout the prostate.

Percutaneous interstitial brachytherapy provides another benefit: The technique is an outpatient procedure, eliminating most hospital stays. Brachytherapy for prostate cancer is performed during two visits.

The first procedure is a prostate-volume study, which determines the dose and number of seeds a patient requires. The second procedure places the seeds. The patient receives spinal or general anesthetic as seeds are inserted through 20 to 25 needles placed through the perineum with ultrasound guidance. Postoperatively, the patient requires only a light dressing for the needle sites and an ice pack on the perineum in the recovery room. He is discharged with minor restrictions and may return to work within one to two days.

Study results
Like any procedure, proper patient selection achieves the best results. Ideally, patients should have a prostate-specific antigen (PSA) level less than 10 and tissue grade, or Gleason score, of six or less. Prostate volume also plays a role as a tech- nical consideration for needle and seed placement but often can be manipulated with preoperative hormone therapy.

Blasko et. al. reviewed their results for interstitial seed therapy for prostate cancer and provide one of the largest series of brachytherapy for prostate cancer. Study results revealed 98 percent of prostate cancer patients (T1 or T2) treated with I123 had a normalized PSA at one year and 93 percent of patients maintained disease-free status (based on PSA failure) at five years based on their actuarial data. 1

Blasko's group compared its results with the prostatectomy series of Lange et. al. (J Urol, 141:873, 1989) and felt that both provided similar survival. Other studies have found higher PSA failure rates of 76 percent, but appear to have included some more advanced tumors.2,3 Blasko's group also looked at post-treatment biopsies and found that 80 percent remained negative at one year with 17 percent indeterminate and 3 percent positive.4

The significance of a positive biopsy remains controversial as it does not necessarily correlate with a rising PSA and some of the indeterminate biopsies can later become negative. This may well be the result of the difficulty in the patho-logical interpretation of a radiated prostate as the morphology can appear distorted after radiation. This uncertainty of post-radiation prostate biopsies makes PSA follow-up a more objective measure of disease recurrence.

Side effects
Side effects from interstitial brachy-therapy appear to be short lived and localized. Urinary-related symptoms, such as dysuria and retention, are the most common — up to 46 percent at one month but resolving to 14 percent at two years in most series. Impotence is seen in 5 to 10 percent of patients after one year and generally higher in those with more aggressive lesions. Rectal complications are seen in 5 to 9 percent and incontinence is seen in only 1 to 3 percent of patients.

Summary
Radioactive seed implantation with either I125 or Pd103 offers a reasonable alternative to surgery or external beam therapy in the management of prostate cancer. Current data suggests it is compar-able to surgery at five years and, in unpublished data, Blasko et. al. state that this is maintained at seven to eight years post-therapy. What is not known are the long-term results to 10 years and beyond.

In order to displace surgery as the mainstay of therapy for localized prostate cancer long term, comparative trials will be required. However, with the current data, ease of administration and low mor-bidity, seed implantation is a reasonable option for those well-selected patients. Until such data is known, radioactive seed implantation is an excellent option for patients with prostate cancer and should be included in the discussion of treatment options with these patients.

For more information regarding brachytherapy prostate cancer threapy, or to refer a patient, please call Nicolas A. Muruve, MD at (800) 877-7197, Ext.4-8747.

References

  1. Blasko J.C., Wallner K., Grimm P.D., Ragde H. J Urol 154:1096-99, 1995.

  2. Stock R.G., Stone N.N., DeWyngaert J.K., Lavagnini P., Unger P.D. Cancer 77:2386-92, 1996.

  3. Stokes S.H., Real J.D., Adams P.W., Clements J.C., Wuertzer S., Kan W. Int J Rad Onc, 37:337-41, 1997.

  4. Prestige B.R., Hoak D.C., Grimm P.D., Ragde H., Cavanagh W., Blasko J.C. Int J Rad Onc, 37:31-9, 1997



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