Fortunately, there are a number of advanced imaging and diagnostic tools available today to locate the site and extent of recurrent disease. Finding the prostate cancer cells in the body is the first step in planning an effective salvage treatment.
When evaluating treatment failure, doctors determine whether the failure is “local,” “regional” or “distant.” A local failure indicates the cancer has reappeared in the area of the prostate (or in the prostate bed, if the gland was removed by surgery). A regional failure indicates the spread of disease is still confined to the prostate and pelvic region. Distant failure indicates there are metastases at sites in the body distant from the prostate, such as lymph nodes or bones. In some cases, there may only be evidence of biochemical recurrence (a rising PSA). Determining whether treatment failure is local or distant is crucial in deciding what options each patient has for future therapy, and whether or not additional therapy is appropriate.
The advanced staging studies we conduct to determine local, regional and distant metastases include:
• Multimodality TRUS imaging (grey scale and especially Color-Flow Power Doppler Ultrasound)
• Dynamic Contrast Enhanced MRI (DCE-MRI)
• 18F-FDG Fluoride PET/CT
• Combidex® USPIO MRI (when available)
• 11C-Choline PET/CT studies
• CTC (Circulating Tumor Cell) blood test
• New Feraheme USPIO MRI analysis
• 3.0 Tesla MRI scans (Magnetic Resonance Imaging)
A distant failure may not be a recurrence per se, but rather an indication of persistent disease that was not detected during the initial workup and staging. In such cases, the cancer was probably there before the primary treatment but not detected by the various diagnostic scans and lab tests. It is important to understand at this point that treating a recurrence is more challenging than initially treating most prostate cancers, whether the relapse is local, regional or distant. There will be a new set of critical circumstances to consider. Primary among these is the condition of the prostate bed or the prostate gland (if first treatment was anything other than surgery).
Surgery (either radical or robotic) leaves a void in the pelvic area that rapidly becomes occupied by the bladder and/or rectum, making salvage radiation therapy a challenge so as not to permanently damage these organs in the process of killing the remaining cancer cells. In addition, the surgical process will have left the area badly devascularized (decreased blood flow). Therefore the “target zone” will be lacking in appropriate oxygenation to activate the highest cancer-killing response of radiation. Higher doses, only achieved by DART (Dynamic Adaptive Radiotherapy), and often accompanied by hormonal therapy, are necessary to salvage a cure.
If the recurrent patient had primary radiation, then he has already received a significant dose of radiation, which makes additional radiation potentially dangerous. To ensure safety, these men will need the higher, precisely targeted doses available only through the sophistication of treatment delivery regimens encompassing all the available tools, especially those associated with DART.
Locating recurrent prostate cancer with advanced imaging techniques (such as USPIO contract agents) allows us to identify small, isolated deposits of cancer—both within and outside the prostate—that can be targeted for more effective treatment with radiation. This is indeed good news for those men who after primary treatment experience an otherwise unexplained rise in PSA that suggests recurrent cancer.
Our state-of-the-art imaging techniques can identify lymph node spread in patients initially treated for high-risk disease, and they are already allowing us to effectively treat patients with positive lymph nodes by utilizing DART. Our expectation is to further increase our cure rate in this group of patients by treating lymph nodes which may otherwise have not been detected and located with specificity without the benefit of contrast-enhanced MRI scanning and Fusion CT imaging. This is perhaps the most exciting research being performed at our center and we believe will result in a paradigm shift as to how more advanced prostate cancer is treated.
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