Imaging Prostate Cancer
Posted: Nov 01, 2018
POSTED: December 12, 2016
Dr. Snuffy Myers says:
Treating recurrent prostate cancer is a major focus in my clinic, the American Institute for Diseases of the Prostate (AIDP). I started seeing patients with recurrent disease in 1994 at the University of Virginia and have seen about 1,000 men at AIDP since we opened in 2003. About half of my patients at AIDP have or had recurrent cancer. The others had metastatic disease at diagnosis, or are on active surveillance. In 1999, I myself was diagnosed with metastatic prostate cancer and today remain concerned about recurrence.
I’ve struggled with the complex issues men with recurrent prostate cancer face. Recurrent prostate cancer is extremely heterogeneous. I have a handful of patients I started seeing in 1994-96 who still haven’t developed diffuse metastatic disease and whose cancers respond to minimal treatment. I also have patients with explosive cancer with doubling times of two to four weeks who rapidly developed diffusely metastatic disease. For much of this time period, the PSA doubling time was the most valuable tool available to determine a cancer’s aggressiveness. PSA doubling times more rapid than three months signaled aggressive disease likely to become metastatic, whereas doubling times slower than nine months were often associated with indolent cancer. This was even more pronounced with doubling times slower than 18 to 24 months. These guidelines are still useful: Dr. Phuoc Tran’s trial uses a 15-month doubling time or slower as an eligibility requirement.
While nomograms based on doubling time and other clinical parameters are useful, there are still patients whose cancer proves more or less aggressive than anticipated. Determining aggressiveness has been improved by molecular marker tests done on tissue obtained at biopsy or at surgery. The sophistication and utility of these tests are advancing rapidly. I agree with Dr. Stephen Freedland that Decipher is currently the most promising one.
Patients with a rapid PSA doubling time are at high risk for developing diffuse metastatic disease. They often have cancer cells in their blood stream, a common means for the cancer to spread to bone, liver, or other organs. Guardant360 is a blood test that sequences a cancer cell’s DNA. We’ve used the test on more than 60 patients to tailor treatment.
This month we also discuss advances in imaging. Identifying patterns of metastatic spread is useful. Clearly, patients with recurrent disease limited to the prostate bed, irradiated prostate, and/or pelvic nodes are likely to have a better prognosis than those with extensive nodal spread or liver and bone metastases. But the most interesting finding is the possibility of true oligometastatic disease: patients might be placed in a durable complete remission with surgery or radiation. As several of our investigators note, even the most advanced imaging techniques don’t identify micrometastatic prostate cancer. Today, imaging alone is not sufficient to identify patients with true oligometastatic disease.
In my experience, patients most likely to benefit from an oligometastatic treatment approach have a PSA doubling time slower than nine months. Durable remissions are much more likely if metastases are limited to the pelvic nodes or a few bone metastases.
I’m very excited by the pace of research in recurrent disease and the quality of the investigators working in this area.