3-dimensional (3D) conformal radiation therapy
EBRT designed to decrease exposure of normal tissues using methods such as CT-based 3-D conformal treatment planning is under clinical evaluation.
Interstitial implantation of radioisotopes
Interstitial implantation of radioisotopes (i.e., iodine-125 [125 I], palladium, and iridium), using a transperineal technique with either ultrasound or computed-tomography (CT) guidance, is being done in patients with T1 or T2a tumors. Short-term results in these patients are similar to those for radical prostatectomy or EBRT.[33,34]; [Level of evidence: 3iiiDiv]
Factors for consideration in the use of interstitial implants include the following:
- The implant is performed as outpatient surgery.
- The rate of maintenance of sexual potency with interstitial implants has been reported to be 86% to 92%.[33,35] In contrast, rates of maintenance of sexual potency with radical prostatectomy were 10% to 40% and 40% to 60% with EBRT.
- Typical side effects from interstitial implants that are seen in most patients but subside with time include urinary tract frequency, urgency, and less commonly, urinary retention.
- Rectal ulceration may also be seen. In one series, a 10% 2-year actuarial genitourinary grade 2 complication rate and a 12% risk of rectal ulceration were seen. This risk decreased with increased operator experience and modification of the implant technique.
Long-term follow-up of these patients is necessary to assess treatment efficacy and side effects.
Retropubic freehand implantation with 125 I has been associated with an increased local failure and complication rate [36,37] and is now rarely done.
Treatment Options Under Clinical Evaluation for Stage II Prostate Cancer
Treatment options under clinical evaluation include the following:
- Ultrasound-guided percutaneous cryosurgery.
- High-intensity–focused ultrasound.
- Proton-beam radiation therapy.
- Other clinical trials.
Ultrasound-guided percutaneous cryosurgery
Cryosurgery is a surgical technique that involves destruction of prostate cancer cells by intermittent freezing of the prostate with cryoprobes followed by thawing.[Level of evidence: 3iiiC]; [39,40][Level of evidence: 3iiiDiv] Cryosurgery is less well established than standard prostatectomy, and long-term outcomes are not as well established as with prostatectomy or radiation therapy. Serious toxic effects include:
- Bladder outlet injury.
- Urinary incontinence.
- Sexual impotence.
- Rectal injury.
(Refer to the PDQ summary on Sexuality and Reproductive Issues for more information on impotence.)
The frequency of other side effects and the probability of cancer control at 5 years' follow-up have varied among reporting centers, and series are small compared with surgery and radiation therapy.[39,40]
High-intensity–focused ultrasound has been reported in case series to produce good local disease control. However, it has not been directly compared with more standard therapies, and experience with it is more limited.[41,42,43]
Proton-beam radiation therapy
There is growing interest in the use of proton-beam radiation therapy for the treatment of prostate cancer. Although the dose distribution of this form of charged-particle radiation has the potential to improve the therapeutic ratio of prostate radiation, allowing for an increase in dose to the tumor without a substantial increase in side effects, no randomized controlled trials have been that compare its efficacy and toxicity with those of other forms of radiation therapy.