Scans Misused in Prostate Cancer

Too many men with low- or medium-risk prostate cancer get CTs and bone scans that aren't recommended for them, suggests a new study.

The scans are intended to tell doctors if cancer has spread beyond the prostate in men with high-risk cancer.

Doing them in other cases is a concern because CTs expose patients to small amounts of radiation — which itself is linked to future cancer risks — and the scans cost the healthcare system extra money, but have little potential benefit.

The research also suggests that not enough men with high-risk cancer get the scans, which means some of them may get treatment for local (confined to the prostate) cancer that's unlikely to help if the cancer has spread.

"In high-risk patients, those are the ones that have a high risk of positive lymph nodes or (cancer that has) spread to the bone," said Dr. David Samadi, a prostate cancer surgeon at the Mount Sinai Medical Center in New York who was not involved in the new study.

"Otherwise, for low-risk disease, the likelihood of finding a positive bone scan or CT scan is low," he told Reuters Health.

Guidelines from the American Urological Association say that doctors should use other measures such as prostate-specific antigen (PSA) testing to determine a man's risk of advanced cancer and then only scan those with high-risk disease to determine the best treatment.

Researchers led by Dr. Jim Hu of Brigham and Women's Hospital in Boston wanted to see how frequently those recommendations were being followed.

They consulted a database of U.S. men covered by Medicare who were diagnosed with prostate cancer in 2004 and 2005 — a total of 30,000 cases.

Both bone scans and CTs were more common in men who were diagnosed with high-risk cancer.

Sixty percent of those men had one of the scans. Still, one-third of men with low-risk cancer and almost half of those with medium-risk cancer had a scan in between diagnosis and treatment.

Hu and colleagues calculated that the cost of unnecessary scans in men with low- and medium-risk cancer billed to Medicare during those two years was about $3.6 million for their study group. (The government-run insurance program paid an average of $226 for each bone scan and $407 for a CT).

Extra scanning not recommended by guidelines "significantly increases Medicare expenditure without improving quality of care rendered for men with newly diagnosed prostate cancer," the authors wrote in the journal Cancer.

And each extra CT scan exposes men to a small amount of radiation, while also providing an opportunity for doctors to catch something "incidental" that may not pose a threat but still leads to more testing or procedures, Samadi said.

Another recent study found that coaching and feedback from peers about the proper use of the tests helped prostate surgeons reduce the number of unnecessary scans they ordered. Samadi thinks many doctors are just trying to be on the safe side by ordering more tests.

"A lot of it has to do with the fact that most urologists when they think of prostate cancer it's almost like a knee-jerk reaction — automatically they think bone scan and CT scan," Samadi said.

The researchers noted that finding four in 10 men with high-risk cancer aren't getting a scan is also "worrisome."

If doctors don't recognize that cancer has spread in some of those men, they said, they won't benefit from treatment directed just at the prostate.