• FRONTLINE CANCER:
Prostate cancer is diagnosed more often in American men than any other form of the disease, with roughly 238,000 new cases each year. That works out to about one in six guys.
In truth, prostate cancer is even more prevalent than these statistics indicate. By age 50, an estimated one-third of American males will have microscopic signs of prostate cancer; by age 65, one-half to two-thirds. The progression is linear with age. By age 100, postmortem studies suggest virtually every man will have developed prostate cancer.
In most cases, fortunately, the cancer is slow-growing and contained: tiny knots of abnormal but benign cells that never escape the prostate gland to pose a serious risk of health and life. But in some cases, prostate cancer can be fast growing and spread to other parts of the body with deadly effect. Almost 30,000 men die of prostate cancer in the United States each year.
Early treatment dramatically reduces the consequences and mortality of prostate cancer. There are a variety of effective therapies, but much rides upon early detection and diagnosis. For men of a certain age, 40-75, that means a regular prostate specific antigen (PSA) screening is recommended.
It’s a simple blood test that measures PSA, a protein produced by the prostate. Elevated levels of PSA are usually associated with the presence of prostate cancer.
However, the PSA test isn’t perfect or 100 percent conclusive. Sometimes, the next recommended step is a biopsy – the actual plucking of a tiny bit of tissue from the gland for more exacting lab analysis. Prostate biopsies are not casually conducted. They can be painful and involve complications, but most health experts, including the National Comprehensive Cancer Network panel for Early Detection of Prostate Cancer, believe that in appropriate situations, the benefits of a prostate biopsy far outweigh its risks.
The chief benefit, of course, is confirmation of the presence and nature of cancerous cells in the prostate. The prostate may be no bigger than a walnut, but finding abnormal cells within it can be akin to looking for a needle in a haystack — while wearing goggles.
Traditionally, prostate biopsies are conducted using ultrasound to create a real-time, two-dimensional image of the gland that physicians employ as a guide to where to inject the needle and extract targeted tissue.
But “with an ultrasound exam, we are typically unable to see the most suspicious areas of the prostate so we end up sampling different parts of the prostate that, statistically speaking, are more likely to have cancer,” said J. Kellogg Parsons, M.D., M.H.S., a urologic oncologist and associate professor in the Department of Urology at UC San Diego School of Medicine and the Moores Cancer Center.
That can produce an inaccurate diagnosis. Physicians might not see suspect tissues. The biopsy needle might miss existing cancer cells and extract only healthy tissue, leaving doctors and patients to mistakenly assume there is no problematic disease.
So Parsons, with Christopher Kane, M.D., chair of the Department of Urology; Karim Kader, M.D., Ph.D.; David Karow, M.D., Ph.D.; Anders Dale, Ph.D., co-director of the Multimodal Imaging Laboratory; and colleagues, has developed a new approach at Moores Cancer Center to improve the precision of prostate biopsy.
They have combined traditional ultrasound technology with a novel, more sensitive type of magnetic resonance imaging (MRI) called restriction spectrum imaging developed at Moores Cancer Center to create a much more revelatory three-dimensional map of the prostate.
“Restriction spectrum MRI is a game-changer,” said Parsons. “It allows us to target the biopsy needles exactly where we think the cancer is located. It’s more precise.”
The Moores team is the first to conduct prostate biopsies this way in the region. Indeed, they plan to soon begin publishing a series of papers in scientific journals describing their work and results.
To be sure, the MRI adds a step in the process, but it’s addition by subtraction: MRI-guided biopsies, when needed, are more accurate and reliable. They reduce both diagnostic uncertainty and the chance that an untapped cancer will continue to grow undetected and untreated until, perhaps, it’s too late.
— Scott M. Lippman, M.D., is director of UC San Diego Moores Cancer Center. His "Frontline Cancer" column on medical advances from the front lines of cancer research and care appears in the La Jolla Light the fourth Thursday of each month. You can reach Dr. Lippman by e-mail: firstname.lastname@example.org