High Dose Rate Prostate Brachytherapy: Dose Escalation to Dominant Intra-prostatic Nodule
Condition: Prostate Cancer
MeSH terms: Prostatic Neoplasms
Study type: Interventional

Summary: 
      This study will investigate the feasibility of using technology of ultrasound guided HDR
      brachytherapy to focally increase dose to regions within the prostate that are heavily
      infiltrated with cancer. Such regions, referred to as dominant intraprostatic lesions (DIL)
      can be visualized using diffusion contrast enhanced MRI employing an endo-rectal coil. The
      magnetic resonance (MR) images can be fused with the planning transrectal ultrasound (TRUS)
      prior to the brachytherapy procedure to design a dose distribution that will encompass the
      malignant volume with higher than the prescription dose. By its nature, brachytherapy has
      subvolumes that receive (for example)125% of the prescription dose or 150% of the
      prescription dose. With TRUS-guided and TRUS-planned HDR these areas can be manipulated to
      coincide with the DIL. The limit of dose escalation has been reached at whole prostate
      external beam doses of 81-86 Gy and still failure rates for intermediate and high risk
      disease are unacceptable. There is much interest in focal dose escalation and TRUS-guided HDR
      brachytherapy is perfectly suited to achieving this.
    

Detailed description: 
      Methods: If a dominant nodule is visualized on dynamic contrast enhanced (DCE) MRI, it will
      be contoured in 3D and the images fused to the planning TRUS study that is done in
      preparation for brachytherapy (of any type: seeds or HDR). The patient's treatment will
      consist of the standard combined external beam (4600 centiGray (cGy) in 23 fractions) and HDR
      brachytherapy boost (2 fractions of 1000 cGy given on days 5 and 15 of the external beam
      course). During each HDR treatment the plan will be manipulated such that the normally
      occurring high dose regions (125%, 150%) are positioned at the site of the identified
      disease. Normally approximately 60% of the prostate volume receives 125% of the dose and 30%
      receives 150%. By ensuring that the inherent dosimetry favors treatment of the known cancer,
      no region of the prostate would be "underdosed". HDR treatments are performed under general
      anesthesia as an out patient procedure.

      Statistical Analysis: This is a feasibility study and the data reported will be descriptive
      including the frequency with which the DIL can be visualized in this population, the DIL
      volume compared to total prostate volume, and the isodose that can encompass the DIL without
      violating dose constraints to adjacent organs (urethra and bladder). Toxicity will be
      monitored and efficacy will be assessed by repeat DCE MRI at 12 months and biopsy at 30
      months.
    

Intervention name(s): HDR interstitial brachytherapy
Intervention type(s): Radiation
Intervention description(s): 2 treatments of 1000 cGy will be delivered to the entire prostate volume while escalating the dose to the visible disease to 1250 cGy
Other intervention name(s): Planning soft ware Varian Medical Systems Vitesse III
Intervention model: Single Group Assignment
Masking: None (Open Label)
Primary purpose: Treatment
Keywords: prostate neoplasms; interstitial radiation; High dose rate prostate brachytherapy; dose escalation