Impotence and incontinence or tumor recurrence—which is better?
Most prostate carcinomas (approximately 80%) are located in the peripheral area of the prostate, close to the neurovascular bundle, the rectum and the bladder sphincter. If the tumor is supposed to be destroyed by HIFU, the tumor tissue has to be highly heated by compact sound waves.
The surrounding tissue gets also heated and damaged partially as the energy radiated through HIFU drains in the surrounding areas—like hot coffee also heats the cup surrounding it. The structures close to the tumor can be damaged just as the fingers of the person holding the cup of hot coffee.
In case of a complete HIFU treatment of a prostate carcinoma up to the prostate capsule we saw a certain risk of impotence by damaging the neurovascular bundle, of a fistula (defective connection between intestine and prostate) or of urine incontinence because of heating the sphincter.
In order to avoid these undesirable complications, the treating physician only has the possibility to keep a safety distance between the treatment area and the adjacent anatomical structures. In this case, parts of the tumor which are close to the prostate capsule usually will not be heated enough, so they remain unaffected.
The result is the tumor tissue growing again—recurrence or recurrence tumors. After HIFU treatment, these are typically located in the postero-lateral and apical parts of the prostate, meaning in areas which are directly adjacent to the neurovascular bundle and the sphincter. In 30 to 70% of all men, we have to report a recurrence of the prostate carcinoma after HIFU.
HIFU is often criticized by surgeons who recommend surgical removal of the prostate (radical prostatectomy) because of these recurrences. The following is forgotten: even after a prostatectomy we have to report recurrences in 30 to 40% of all cases. Furthermore, most men are impotent after a surgical ectomy and many are incontinent. In addition, a HIFU therapy can be repeated, unlike a removal or radiation therapy (Brachytherapy, external irradiation, protons, etc.). If a sufficient distance to sensitive structures is maintained during HIFU, the risk of impotence and incontinence can at least be minimized—a consideration between a higher quality of life and an increased risk of recurrences.
NanoKnife makes these hitherto quite justifiable considerations obsolete, since IRE allows us to treat the prostate carcinoma without damaging the surrounding structures. We therefore stopped employing HIFU even for focal therapy of prostate cancer.