Stratifying patients based on their relative risk of recurrence has long been an inexact science. Between 30 percent and 50 percent will have their cancer return due to undertreatment of aggressive disease that has already spread outside the prostate gland but was not found during their initial procedure. At the same time, men who are defined as low to intermediate risk are often overtreated because current tests are unable to identify those who have more aggressive disease. This can cause unnecessary treatment leading to toxicity and unneeded expense.
This new test can be done on standard biopsy samples taken prior to treatment. The tissue is first analyzed for abnormal DNA, and then tested for oxygen content, because hypoxia, or low oxygen, has already been identified as a factor in the spread of prostate cancer. When both factors are taken together, the test, which takes only three days, can predict the level of recurrence risk with higher accuracy than any other published test available.
To produce this test, researchers used biopsies from three separate groups of patients: 126 men who had been treated with image-guided radiotherapy, 154 men whose tumors had been removed surgically at Memorial Sloan Kettering, and another 117 surgery patients from Cambridge, England. Remarkably, this new test produced similar results in all three groups, as did the test for hypoxia. Combining the tests made the information even more accurate.
“Our findings were duplicated by researchers at other centers working with different patient samples,” said Adrian S. Ishkanian, M.D., assistant professor of radiation oncology at the Miller School. “This is the most important aspect of the test, because it can be applied to patients treated either with surgery or radiation, and is really the first of its kind that is this accurate for both groups.”
Differences in test results revealed dramatically different outcomes. Those men whose biopsies showed both low levels of genetic changes and low hypoxia had only 7 percent recurrence in five years. Men whose levels were high for both genetic changes and hypoxia, however, had more than 50 percent recurrence.
“We now have the best way to identify which men with low risk or intermediate risk can be watched instead of treated, and which need enhanced treatment, perhaps even more aggressive than is currently considered standard of care,” said Ishkanian.
The researchers’ hope is that this test can help reduce prostate cancer death rates and increase cure rates by more accurately determining what types and levels of treatment are required. Meanwhile, the research is ongoing, with plans to test thousands more patients worldwide in the next three to five years.
“We’re very excited about these results, and we believe the test will dramatically improve our ability to provide truly personalized cancer care,” said Ishkanian.
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