The Food and Drug Administration (FDA) has granted approval for a novel imaging agent that can identify prostate cancer after it has spread to other regions of the body.
According to experts, the tracer, made by Lantheus, will provide clinicians with a vital tool for visualizing prostate cancer cells, guiding them to areas of the body where the cancer has spread, something that would be hard to spot without the new imaging agent.
Prostate cancer is the second highest cause of cancer mortality among males in the United States, claiming the lives of over 34,000 men every year.
When prostate cancer develops, it commonly moves into the bones, according to Dr. Michael Morris, an oncologist at Memorial Sloan Kettering Cancer Center. This creates difficulties for standard imaging techniques in identifying malignancies, he said.
The new method employs a tracer agent that searches for a protein called prostate-specific membrane antigen, or PSMA, which is located on most prostate cancer cells. During a PET scan, the tracer, which is injected into the bloodstream, illuminates the cancer cells.
“It’s really hard to take pictures of what’s going on inside of bone,” Morris said, adding that traditional scans tend to find problems in the tissue surrounding bones, after damage has already been done.
“Now we don’t have to wait for that,” Morris said, who was involved with clinical trials of the tracer. “We can detect it much more clearly and much earlier than we could before.” The scan isn’t intended to take the place of routine PSA testing, which is a common technique for detecting prostate cancer. It’s designed for males who have already been diagnosed with prostate cancer.
“We’ve been using [PSA testing] for many years and it works great,” said Dr. Thomas Hope, director of molecular therapy in UCSF’s Department of Radiology and Biomedical Imaging. “We can actually see where the disease is and now people are getting targeted radiation.”
“It’s redefining how we think about prostate cancer,” he said.
Dr. Xiao Wei, a Boston oncologist, remarked on the new technique, noting that it would be particularly beneficial for prostate cancer patients who have increased PSA levels following therapy, such as surgery or radiation. A rising PSA level means the disease has spread to other parts of the body.
“The huge looming question is, does it actually impact what we do for the patient? Will that help us improve outcomes?” said Dr. Justin Gregg, an assistant professor of urology and health disparities research at MD Anderson Cancer Center in Houston.
Experts say it’s still unclear what exactly physicians should do with the information acquired from the new method. Treatment for prostate cancer is generally tailored to a man’s age, risk factors, and other considerations. Additionally, the treatment can have negative side effects such as impotence and incontinence.
“We may find deposits, but in an elderly man 75 or 85 years old, they might sit there and not require urgent treatment,” said Dr. Derek Raghavan, president of the Levine Cancer Institute in Charlotte, North Carolina. “There is also a variant of prostate cancer that can be metastatic and actually not harm the patient for several years.”
“My guess is that as they develop the technology,” he said, “they will develop a refined method for identifying those with a rapid growth potential.”