More and more, men diagnosed with low grade prostate cancer are choosing to defer treatment, preferring to monitor the status of their cancer by having regular blood tests and tissue biopsies that are designed to let them know if they need to be treated or if they can continue to hold off.
The practice is called “active surveillance.” The problem is that the tests are not definitive. Sometimes, a cancer can be growing or turning more aggressive but the testing may not show it.
Now, a study done by doctors at Beth Israel Deaconess Medical Center has shed more light on which of these cancers are more likely to progress. The findings could help men in making the decision to watch and wait or go ahead with surgery or radiation treatment.
“This is going to be very helpful for patients in choosing active surveillance,” said Dr. William C. DeWolf, senior author and Chief of the Division of Urological Surgery at BIDMC.
“Active surveillance is the most up and coming strategy available to patients who are realizing they can have prostate cancer and not necessarily have it treated if their tumor is low grade,” he added. “We’re trying to save quality of life. But in order to do that, we have to know how to predict if you are a good candidate or not. When you have cancer you want to know your odds. Does it have to be treated or can it be left alone?”
In the study of 135 men who were followed for as long as ten years, tests showed the cancer was progressing in just 30 percent. The other 70 percent of subjects showed no progression and were allowed to continue in the study.
Risk factors for those who saw their cancer progress were those with a family history with prostate cancer or those with a PSA density of greater than .08 ng/ml/cc of blood.
The PSA test is a blood test that measure levels of a protein linked to prostate cancer. A high PSA level is usually the first indication that there may be a problem.
PSA density measures the level of the protein in relation to the size of the prostate itself. It is derived by dividing the PSA number by the gland volume in cubic centimeters (ccs).
DeWolf said those with a family history and a PSA density greater than .08 have a 50 percent chance of seeing their cancer progress within two years. Those with no family history and a PSA density of less than .08 have a 30 percent chance of progressing within eight years, he said.
In addition, another factor that plays a role in the predictive process is PSA velocity, or how fast PSA levels increase. If a man’s PSA score doesn’t increase between trhe first and second biopsies more than .1 – for example from 6 to 6.1 ng/mL of blood – and this factor is added to that of family history and PSA density, the odds of his cancer progressing are about 15 percent over eight years, DeWolf said.
“We are using this information to personalize therapeutic decisions as best we can,” said Dr. Glenn Bubley, director of Genitourinary Oncology at BIDMC and a co-author of the study that appeared in the Journal of Urology this past February. “We can give the patient some sense of what his risk of progression might be.”
Many men with prostate cancer don’t want to be treated if they don’t have to because the treatments carry a high risk of impotence or incontinence.
The men who were enrolled in the study were all considered to have low-grade cancer — based on their initial biopsy results. They had to have cancer in fewer than three of the tissue cores taken, no more than 50 percent cancer involvement of each of the positive cores and the grade of the cancer had to be less than 6 on what is known as the Gleason scale, which measures aggressiveness.
All patients were monitored with 20-core biopsies every 12 to 18 months. A total of 21 patients — 17 percent of those who progressed during the study — had shown cancer progression at the time of their first re-biopsy, according to Dr. DeWolf.
“The purpose of this paper was to devise a statistical system so we could tell people what the odds are that they will progress,” Dr. DeWolf said. “We found as they entered the study if they did not have a family history and had a PSA density of less than .08, the odds of progressing would be around 30 percent. This helps people understand whether it is worthwhile to not get treated and just go on active surveillance verses getting treated.”
Co-author Dr. Marc Garnick, an oncologist specializing in prostate cancer at BIDMC and editor of the Harvard Medical School Annual Report of Prostate Diseases, said most men can go a long time without treatment.
“The bottom line is that two-thirds of men who have prostate cancer with certain characteristics can go long periods without being treated or they may never need to be treated,” Dr. Garnick said. “I’ve had a patient on active surveillance for 16 years.”
Besides this study, which is continuing, BIDMC is participating in a national trial of active surveillance known as the Prostate Cancer Active Surveillance Study (PASS). Dr. Martin Sanda of BIDMC is enrolling patients in this study, which is designed to identify and validate biomarkers — proteins, DNA, RNA, hormones — that predict aggressive prostate cancer.
BIDMC already has the largest single-institution active surveillance study cohort in New England with 150 patients currently enrolled.
Above content provided by Beth Israel Deaconess Medical Center. For advice about your medical care, consult your doctor.