More than 20 years after prostate specific antigen (PSA) screening for detecting prostate cancer was introduced, physicians are working to refine its use as a diagnostic tool.
According to Gerald Andriole, MD, urologist at the Siteman Cancer Center at Barnes-Jewish Hospital and Washington University School of Medicine, a “risk-adjusted screening” approach to PSA testing may be of the greatest benefit to men overall.
“Risk-adjusted screening means making sure men at the highest risk for developing prostate cancer receive regular PSA tests. For the rest of men— the majority—it means getting a baseline PSA test around the age of 45 and then getting screenings every five to 10 years thereafter, according to the rate at which their PSA rises,” explains Andriole, who also is the R.K. Royce Distinguished Professor and chief of urology at Washington University.
Those at highest risk for prostate cancer are African-American men; men with two or more first-degree relatives with the disease, particularly if they were diagnosed at age 60 or younger; and men in their 40s who have high PSA scores. “Rates of prostate cancer in African-American men are twice as high as those in other American men, as is their death rate from the disease,” says Siteman urologist Arnold Bullock, MD. “These facts make it imperative for African- American men to get their first PSA test between ages 40 and 45. If those results are within acceptable ranges, then at age 50 they should begin getting PSA screenings annually. Men in the other high-risk categories should consider following the same course of screening.”
Over Diagnosis, Over Treatment
Although annual PSA screening is not harmful, the actions a man may take after receiving test results that indicate high PSA levels sometimes are.
“It can be a slippery slope that begins when a man learns he has an elevated PSA. For some, that leads to having a biopsy because they worry about having cancer. If the biopsy does show cancer, there may be a reaction from the patient or his family—particularly in the United States—to do something immediately,” says Andriole. “That ‘something’ often means surgery or radiation treatment, which can result in serious adverse side effects like impotence and incontinence.”
This chain of events is proving to be unnecessary for a lot of men with prostate cancer. Andriole cites the findings of the National Cancer Institute’s Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial, in which 76,000 men have been followed for 10 years or longer.
“The study’s data confirm that for most men it is not necessary to be screened annually for prostate cancer since the large majority of the cancers we found are slow-growing tumors that are unlikely to result in death,” says Andriole, who serves as the chairman of PLCO’s prostate committee. “For that reason, we need to modify our current practices and stop screening elderly men and those with a limited life expectancy. Instead, we need to take this targeted approach and selectively screen those who are most likely to benefit—young, healthy men and those with a high risk for the disease.”
For men diagnosed with prostate cancer, an alternative treatment approach is active surveillance. An increasing number of men are taking this option when a biopsy shows a small amount of cancer in the prostate and microscopic examination indicates it has a low chance of growing aggressively.
“Studies are showing that 60 to 70 percent of prostate cancers can be treated in this way because of the slow-growing nature of the tumors,” says Andriole. “For these patients, we repeat PSA testing every three to six months. If there is no change or it rises only slowly, we do another biopsy in a year’s time. If the cancer has worsened, then we can begin discussing treatment options.”
James “Terry” Gates, 75, a retired college professor, is one of Andriole’s patients who chose active surveillance. Gates was diagnosed with prostate cancer about two years ago. “I knew I didn’t want aggressive, invasive treatment if I could avoid it. The low level of discovery in regard to the cancer convinced me to simply get a PSA screening every six months or so. My PSA score has remained at about the same level,” says Gates. “I have confidence in my doctors, and I’m 75. My attitude might be different if I was 30 years younger, but at this stage of my life, this was a realistic choice for me.”
Several advanced technologies aid in the diagnosis and treatment of prostate cancer. One of these, TargetScan, a three-dimensional ultrasound, helps to calculate the size and shape of the prostate and to define the location of the cancer.
Its accuracy allows urologists to perform follow-up biopsies in the exact area where cancer was previously detected, thus providing a more exact assessment of the cancer’s progression. It also aids in radiation therapy and in an investigational treatment called focal ablation, which uses freezing to destroy tumor tissue.
High-strength magnetic resonance imaging (MRI) with a 3 Tesla (3T) magnet, which can show the location and size of prostate cancers, is another available tool. The information it provides helps determine whether active surveillance is a viable option.
“Both TargetScan and 3T MRI can help us with focal ablation of small cancers,” says Andriole. “Since we know the precise location of the tumor from the TargetScan and/or MRI, we can insert a needle into that region of the prostate and destroy it. Treating the cancer in this way increases patients’ odds that they will remain on active surveillance without the need for other, more aggressive treatment in the future. This ‘micro-invasive’ approach to prostate cancer is apt to become more widespread in the
Often, men choose intensitymodulated therapy, which targets higher doses of radiation to the prostate and less to surrounding organs. Others opt for brachytherapy, in which radioactive seeds are implanted into the prostate to kill cancer cells. These treatment methods also employ either TargetScan or 3T MRI to assist with precise targeting of the radiation.
“There is no one treatment that is right for every man,” says Siteman radiation oncologist Jeff Michalski, MD, vice chairman for radiation oncology at Washington University School of Medicine. “I often tell my patients that what worked for their neighbor or their best friend may not be the best treatment for them. That’s why men who undergo treatment for prostate cancer need to understand the risks and benefits of surgery and radiation therapy.”
Michalski adds, “Patients should choose a radiation oncologist or surgeon who specializes in treating prostate cancer. Their outcomes generally are better, and patients have fewer complications during treatment and after.”
What the Future Holds
In an ideal world, doctors would have a better way to identify which prostate cancers need to be treated and which pose no threat. Work to find genetic and protein markers that characterize aggressive prostate cancer is under way. Men whose tumors have these markers would easily be identified and treated.
“Until that type of testing is available, active surveillance will continue to be a viable option for many patients with prostate cancer,” says Andriole. “It’s a management strategy that always can be re-addressed at any time. Surgery and radiation therapy are irreversible.”