A diagnosis of low-risk prostate cancer usually means that the cancer is slow-growing enough that men can choose active surveillance rather than immediate treatment. But, in reality, determining whether a prostate cancer might actually be aggressive can be difficult, leaving men wary about whether they risk their lives with such surveillance, commonly called watchful waiting.
Accurately diagnosing prostate cancer aggressiveness can be difficult.
Steven Smith, Ph.D., professor of molecular science at City of Hope, is working to allay fears that such cancers might have already spread beyond the prostate gland. He's developing a test to assess the risk of whether suspected slow-growing disease is more aggressive than thought.
Already, physicians use many tools – such as PSA tests, biopsies and Gleason scores – to help them determine what kind of tumor patients have, but the accuracy of such tools can vary. The most accurate diagnosis is made with the removal of the prostate gland and a complete pathological exam; assessing whether a tumor has spread beyond the prostate gland is done at the time of surgery.
In a study presented earlier this year, City of Hope researchers found that – among almost 1,300 men diagnosed with low-risk prostate cancer who had their prostate glands removed – 36 percent actually had higher-risk prostate cancer.
In a new study, Smith and his research team conducted DNA testing of fluid samples from 536 men about to undergo prostatectomy, of whom 234 were eligible for active surveillance using current guidelines.
The researchers found that two measures – volume and amount of RNA from the fluid specimen – could help confirm whether a patient was actually at higher risk of having cancer that had spread beyond the prostate. Overall, the potential new test identified only 114 men who would have been eligible for active surveillance, Smith said.
"In this group, 42 men, or 36 percent, were shown to have a higher-grade cancer after a complete pathological exam of their removed prostates, but only two men were discovered to have cancer that spread beyond the prostate gland," Smith said.
Another review of City of Hope's prostate cancer patients found that 5 to 8 percent of men diagnosed with low-risk disease actually had a tumor that had spread beyond the prostate gland, discovered during the prostatectomy. If the new test had been used to help determine eligibility for active surveillance, that 5 to 8 percent risk could have been cut five-fold, Smith said.
Such data adds impetus for the need to clarify who can rely on watchful waiting – and who can’t.
The study was recently presented at the American Urological Association western section meeting. The research team included Christopher Whelan, M.D., Mark Kawachi, M.D., David Smith, Ph.D., Jennifer Linehan, M.D., Gail Babalona, B.S., and Timothy Wilson, M.D., the Pauline and Martin Collins Family Chair in Urology.
The researchers said in the study's abstract: "Testing of the type we describe may improve patient acceptance of active surveillance by reducing the risk of non-organ confined disease."
NIH Grant #s: CA102521 and CA136055