ORLANDO, FL—Although about half of patients with low-risk prostate cancer show disease progression with active surveillance, a new study reported here at the Genitourinary Cancers Symposium suggests that the risk of dying from the disease is a rare event
“Only one observed prostate cancer-specific mortality was identified, which speaks to the value of active surveillance in appropriate patients,” David Buethe, MD, a urologic oncology fellow at Moffitt Cancer Center, reported in a poster study (Abstract 170).
He and his colleagues followed 96 patients, 52 of whom had disease progression. Seventeen of the men with disease progression had an increased Gleason score; in 21 men, the tumor volume increased, and in 14, there was both an increase in volume and a rise in Gleason score.
“With time, about 50 percent of patients can expect disease progression with long-term surveillance,” Buethe noted.
Among the men for whom no progression was observed, 35 remained untreated while nine did opt for treatment.
In the retrospective study, the research team identified 114 men who were placed on active surveillance for prostate cancer between November 1997 and November 2000. Of that group, 96 met the inclusion criteria of having a Gleason score of less than 7; tumor presence in less than four sextets; involvement of less than 50 percent of any single biopsy core, and at least one follow-up biopsy.
Eligible patients were surveyed by serum prostate-specific antigen (PSA) tests, digital rectal examination, and surveillance transrectal ultrasound-guided biopsies at intervals determined by the individual physicians.
At diagnosis, the patients' mean age was 70.3, and the mean PSA value was 8.2 ng/mL. The patients had their PSA tested about every nine months and underwent a transrectal ultrasound every 1.5 years.
The median number of PSA tests was six, and the median number of biopsies was 3.5. After a mean follow-up of about 135 months, 52 patients had been reclassified or had demonstrated disease progression.
That translated to a median disease-free progression of 68.7 months, and a median overall survival of 156.9 months, he reported.
Asked his opinion for this article, Ian Thompson, MD, Professor and Chair of Urology at the University of Texas Health Science Center at San Antonio, said that although this is a fairly small group of patients on active surveillance, the length of follow-up of more than 10 years is reasonable.
“These findings regarding disease-specific survival are very reassuring. The study had a reasonable number of people who progressed, but the challenge with progression is that no one knows what the right definition of progression is,” Thompson said.
“We do know that patients with Gleason 6 prostate cancer often are reclassified as Gleason 7 on re-biopsy. That is often deemed to be progression and leads to intervention. But in our personal experience here and in other institutions, localized Gleason 7 prostate cancers really behave about the same as Gleason 6 cancers.”
Buethe noted that exactly what the criteria for active surveillance should be is not standard. He surveyed nine centers on what their active surveillance guidelines are, but there was no consensus. Many centers use PSA—although the cutoff values differ from institution to institution—and cancer stage. Most use Gleason sum scores; only a few use tumor volume.
“Inclusion, progression, and surveillance criteria lack evidence-based standardization,” he said.
“My take-home message from this study is that active surveillance remains a reasonable option for selected patients. When you tell patients about the risk of low volume, Gleason 6 prostate cancer, they embrace active surveillance joyously.”
He did note, however, that patients who elect active surveillance have to “put up with the nuisance of active surveillance, which is pretty intensive—testing every six months and a biopsy about every two years—and know that there is still a very small risk of disease progression. Of all the hundreds of patients included in these studies of active surveillance there are four or five deaths due to prostate cancer.
“I think active surveillance is underutilized,” Thompson continued. “Studies have indicated that only about 10 percent of men who are eligible for active surveillance are actually managed with it.
“There are no panaceas for the low-risk prostate cancer patient. Active surveillance will avoid the side effects of radiation or surgery. There is a 60 to 70 percent risk of erectile dysfunction and the urinary side effects. There is also the risk of radiation injury and the risk of secondary malignancies after radiation. When you add up the risks of side effects that go into the range of 30, 40, 50 percent, and you compare it with the risk of dying of prostate cancer—about one percent in this study and in others—it gives a person pause to think about this.”