Prostate MRI and thermal ablative therapy for prostate cancer
Recent advances in multiparametric MRI of the prostate allow identification of focal prostate cancer
with high sensitivity and specificity (1). As prostate cancer becomes visible by new imaging techniques,
a shift in treatment strategies occurs . Rather than radical “whole-gland” elimination triggered by
positive results obtained during multiple blind transrectal biopsies, targeted biopsy and focal therapy is
achievable and moves the treatment of prostate cancer into more traditional patterns of cancer
diagnosis and care, such as that seen with breast imaging and lung cancer CT screening.
Recent multicenter trials in Europe and the US, including the most recent PIVOT trial (2-6) indicate that,
in the setting of biopsy-proven non-aggressive prostate cancer, the 10 year mortality is no different in
men who undergo radical prostatectomy versus surveillance. Given the indolent behavior of most
prostate cancers and the life-changing complications of whole gland therapies or prostatectomy, a focal
tumor ablation method with fewer side effects and shorter recovery is a welcome alternative.
Laser interstitial tumor therapy (LITT) is used in several areas for tumor treatment and for control of
seizure foci in patients with refractory epilepsy. The Visualase laser ablation system in use at UTMB
consists of 50 watt diode lasers tuned to 980nm and proprietary software which enables MRI
thermometry or real-time temperature measurement during tumor ablation using a special MRI
sequence. Interventional radiologists at UTMB have experience in treating over 20 patients with LITT,
including cancers in the kidney, liver, prostate and lung. This newer thermal ablative technique is
cleared by the FDA for human use and seems especially suited for prostate cancer for three main
reasons:
1) Laser ablation is carried out in MRI which is the only modality able to visualize prostate cancer
with sufficient sensitivity and specificity.
2) Lasers create a very focal ablation with a sharp margin. This increases safety particularly around
the neurovascular bundles (responsible for micturation and sexual function) which frequently
lay close to prostate tumors in the peripheral zone.
3) MRI sequences can show tissue temperature in real-time. Therefore, the extent of tumor
ablation is visible as it occurs.
4) The ablation time for laser is very short (90 sec to 3 minutes)
5) There is some evidence that laser ablation may cause immunostimulation of the host against
remaining or recurrent tumor cells
The purpose of this study is to investigate the safety and effectiveness of focal ablation for prostate
cancer. The data collected on enrolled patients will allow us to calculate:
1)
2)
3)
4)
Recurrence rates
Metachronus cancers
Metastases
PSA (chemical) response
5) Imaging response
6) Complications of ablation
7) Change in lower urinary tract symptoms (LUTS) post ablation
PROTOCOL
PURPOSE: Evaluate the safety and efficacy of LITT for MRI-visible prostate cancer
INCLUSION CRITERIA:
1)
2)
3)
4)
5)
Age over 21 and able to consent
MRI shows focal unilateral lesion confined to prostate
TRUS or MR guided biopsy proof of prostate cancer
Acceptable coagulation factors
Acceptable renal function
EXCLUSION CRITERIA
1) Metastatic disease
a. Bone scan
b. CT abdomen/pelvis
2) Gleason score >7
3) Bilateral or diffuse lesions
4) Previous focal therapy
MATERIALS/METHODS:
Patients referred for LITT fit into three categories:
1) Transrectal ultrasound guided biopsy (TRUS) positive for prostate cancer with MRI positive for
cancer suspicious lesions that correlate with biopsy results
2) Patients with high PSA levels but no biopsy. MRI shows lesion with MR-guided biopsy positive
for prostate cancer
3) Patients with previous negative TRUS biopsies and MR positive lesion with MR-guided biopsy
also positive
Patients undergo MRI, MR-biopsy (if needed), and clinical assessment. If they satisfy inclusion/exclusion
criteria, they can receive LITT.
Patients require labs and imaging within 60 days of LITT including
1) Creatinine and electrolytes
2) Complete blood count and coagulation panel (PT/PTT)
3) MRI prostate with gadolinium enhancement
LITT is performed using Visualase system with transrectal or transperineal guidance.
After ablation, patients are followed clinically and by repeat MRI and PSA level in 6 months and one
year, and then yearly. MRI biopsy is performed for recurrent lesions. Treatment of recurrences is
dictated by referring urologist
Data collected includes:
1)
2)
3)
4)
5)
Labs
Imaging characteristics
Histopathology of biopsy specimens
Follow up imaging/labs/clinical exam
Sexual health in men (SHIM ) score and International prostate symptom score (IPSS) preprocedure and at all follow up occurances therafter.
Subjects recruited: 30