An analysis of patients with prostate cancer treated in Minnesota found 13 percent of patients underwent imaging after suspected disease recurrence. However, only three percent underwent imaging in the absence of clinical symptoms of cancer recurrence.

The findings showed physicians were mostly adherent to the American College of Radiology (ACR) guidelines that suggest patients with prostate cancer only undergo imaging after suspected cancer recurrence.

Lead researcher Jennifer S. McDonald, PhD, of the Mayo Clinic’s department of radiology in Rochester, Minn., and colleagues published their results in the November issue of the American Journal of Roentgenology.

“Our analysis of a local cohort of posttreatment patients with prostate cancer determined that imaging examinations are not frequently ordered in the absence of suspected cancer recurrence,” they wrote. “However, a wide variety of imaging examinations was ordered in patients with suspected recurrence. This variation suggests that additional provider education and reanalysis of recommendations by the ACR Appropriateness Criteria panel may be needed.”

In 2015, an estimated 220,800 men in the U.S. will be diagnosed with prostate cancer, which the researchers noted is the most common noncutaneous cancer in men in the U.S. They added that patients with prostate cancer are most often treated with radical prostatectomy, radiation therapy and hormone therapy and are also typically followed with serum prostate-specific antigen (PSA) level measurements and digital rectal examinations (DREs). If PSA levels are higher than baseline readings, patients then often undergo imaging to determine if the prostate cancer has recurred or metastasized.

In 2011, the ACR updated its guidelines that detail the types of imaging examinations that are considered appropriate or inappropriate and divide patients up depending on the type of treatment they receive.

If patients have clinical indications of cancer recurrence, they are often recommended to undergo radionuclide bone scans or CT and MRI examinations of the abdomen and pelvis.

This study included 670 residents of Olmsted County, Minn., who participated in the Rochester Epidemiology Project and were treated for prostate cancer from 2000 through 2011. Patients were excluded if they were diagnosed with metastatic cancer.

Of the patients, 59.6 percent underwent prostatectomy, 30.6 percent received radiation therapy and 17.8 percent received androgen deprivation therapy.

During the study, 22 percent of patients had documented suspicion of cancer recurrence based on elevated PSA levels, abnormal DRE findings or bone pain. In addition, 13 percent of patients underwent 241 imaging examinations ordered by 84 providers after suspected recurrence of prostate cancer.

The most common modalities ordered were CT of the abdomen or pelvis, endorectal coil MRI, spinal x-ray, and bone scan. Of the patients who had an imaging examination after suspected prostate cancer recurrence, 69 percent underwent a bone scan as their first imaging modality or in combination with other imaging modalities. Meanwhile, 16 percent of patients with suspected recurrence underwent chest x-ray examinations.

“These findings show that there is substantial variability in which imaging examinations are chosen by providers for monitoring prostate cancer,” the researchers wrote. “Urologists were less likely than oncologists to order a bone scan as the first imaging modality. One explanation may be that oncologists are more likely to see patients who are more at risk of developing metastases, whereas urologists are more likely to see patients who are more at risk of local recurrence. Furthermore, urologists may be more familiar with patients with low- or intermediate-grade tumors and slow PSA doubling times, which are more indicative of local recurrence.”

The researchers mentioned a few study limitations, including that the results may not be generalizable to other practices and regions. The trial also did not include new imaging technologies such as C-choline PET/CT. In addition, the researchers noted that patients may have had PSA testing, imaging or other prostate cancer management at outside centers. Further, they did not know why the providers ordered imaging examinations.

“We therefore cannot conclude whether incidences of nonadherence were attributable to lack of knowledge about the ACR guidelines or intentional deviation from the guidelines for legitimate clinical reasons,” they wrote. “Prospective studies that directly survey providers to determine the reasons for ordering imaging examinations would provide a more accurate picture of imaging utilization.”