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Focal therapy

The aim of all of these investigational therapies is to provide satisfactory oncological control, with a reduction in the morbidity associated with conventional treatments.

Other goals are long term efficacy on extended follow up, allowing for options for salvage curative therapy in cases of recurrence.

 

Cryotherapy

  • Rapid freezing, followed by gradual thawing, then repetition of the freeze-thaw cycle -> disruption of organelles and cell membrane -> delayed microcirculatory occlusion causes cellular hypoxia
  • Delivered by cryo-needles under TRUS guidance as well as thermo-sensors at the sphincter and rectal wall. Also a urethral warmer is placed.
  • Side effects:
    • ED up to 18 %
    • Urinary incontinence 2 – 20 %
    • Urethral sloughing up to 38 %
    • Rectal pain and bleeding
    • Recto-urethral fistula, up to 6 %
  • No long term prospective comparative data

HIFU

  • High intensity ultrasound primarily causes cell death by thermal effects (coagulative necrosis secondary to heat) but also has some mechanical effects (cavitation)
  • Initially used for whole gland treatment, but now being used as focal therapy in some centres
  • Side effects:
    • Urinary retention 10 %
    • ED up to 23 %
    • Stricture up to 8 %
    • Rectal pain and bleeding
    • Urinary incontinence 10 %
    • Recto-urethral fistula, up to 5 %
  • No long term prospective comparative data.

 

Focal therapies

Irreversible electroporation (NanoKnife)

  • Non thermal – delivery of high voltage short pulse electrical currents creating cellular membrane nanopores, leading to apoptosis

Others – laser interstitial thermotherapy; photodynamic therapy; focal SBRT (cyberknife).

All of these therapies are considered experimental and should only be offered within a clinical trial setting

 

Argued benefits:

  • Provides another option for cancer treatment for those unwilling or unfit for radical treatment
  • Less morbidity than radical treatment
  • Allows retreatment
  • May not preclude whole gland treatment in future
  • Focal therapy is not a new concept – parallels to breast cancer etc

 

Arguments against / disadvantages

  • No known data on long term outcomes oncologically or functionally
  • Likely poorer oncological outcomes cf. surgery
  • Prostate cancer often multifocal disease
  • Expensive and not funded
  • Makes salvage treatment more difficult and morbid
  • Difficulty interpreting treatment ‘success’