Studies published in the past few years have documented overuse of radiologic imaging, such as bone and computed tomography (CT) scans, for the initial staging of low-risk prostate cancer (PCa), but the findings of most studies were based largely on data captured up to a decade or more ago. Since then, a growing body of evidence has led to widespread acceptance that low-risk prostate tumors rarely lead to metastatic disease, and most patients with these tumors do not require treatment. Responding to the research, physician organizations, such as the American Urological Association (AUA), have updated clinical practice guidelines to discourage radiologic imaging in patients with low-risk PCa. Although contemporary data on physician use of radiologic imaging for these patients are sparse, some evidence points to a downward trend. For example, a study of men diagnosed with PCa from 2004 to 2011 within the Colorado and Northwest regions of Kaiser Permanente found 35% of men with low-risk disease received non-indicated imaging at diagnosis. Compared with men diagnosed in 2004, however, those diagnosed in 2011 had 70% reduced odds of receiving non-indicated imaging at diagnosis.¹

Some urology thought leaders believe overuse of radiologic imaging for low-risk PCa is declining. Neal D. Shore, MD, president of the Large Urology Group Practice Association and Director, CPI, Carolina Urologic Research Center in Myrtle Beach, South Carolina, said he has not seen recent trend data on inappropriate radiologic imaging for low-risk PCa, but noted: “My expectation is that it’s decreased substantially. I’m not aware that it’s still a significant issue. The evidence-based literature is pretty clear on the lack of need to get [radiologic imaging] for patients with low-risk disease.”

Jim C. Hu, MD, MPH, of Weill Cornell Medical College in New York, who led a study showing widespread overuse of radiologic imaging for low-risk PCa based on 2004–2005 data,² said an analysis of more recent data likely would show a decrease in the overuse of bone scans and CT scans.

Downward trend explained

Speaking on behalf of the AUA, Matthew J. Resnick, MD, MPH, Assistant Professor of Urologic Surgery and Health Policy at Vanderbilt University Medical Center in Nashville, Tennessee, said ample evidence suggests overuse of imaging for low-risk PCa, but the magnitude of overuse appears to be declining. Reasons for this trend, he said, include development and diffusion of clinical practice guidelines discouraging radiologic imaging for low-risk PCa, as well as initiatives such as the Choosing Wisely campaign, which aim to promote discussions centered on the use of low-value health care services. “Importantly, however, as we continue to learn more about the indolent natural history of low-risk prostate cancer, both providers and patients have become increasingly comfortable withholding imaging,” Dr Resnick said.

The Choosing Wisely campaign is an initiative of the ABIM Foundation. As part of the campaign, AUA in 2013 included in a list of commonly used tests and treatments of questionable value a statement that a routine bone scan is unnecessary for men with low-risk PCa. The 2017 AUA guidelines for managing low-risk and very-low-risk localized PCa state that clinicians should not perform abdomino-pelvic CT or routine bone scans. In a paper titled “Challenges and Recommendations for Early Identification of Metastatic Disease in Prostate Cancer,” which was published in Urology (2014;83:664-669),³ members of the Prostate Cancer Radiographic Assessments for Detection of Advanced Recurrence (RADAR) Group recommended against radiologic scanning for newly diagnosed low-risk patients and most intermediate-risk patients.

The Michigan experience

In some places, overuse of imaging for low-risk PCa declined following interventions to discourage it. For example, earlier this year, researchers reported on a study of men with newly diagnosed low-risk PCa in Michigan showing that the proportion of those who received inappropriate bone scans and CT scans decreased from 11% and 14.7%, respectively, in 2012–2013 to 6.5% and 7.7%, respectively, in 2015 following implementation of statewide interventions designed to improve imaging utilization for PCa staging.⁴ The findings are from an analysis of data from 10,554 patients in the Michigan Urological Surgery Improvement Collaborative registry. The collaborative comprises 42 diverse practices representing 85% of the urologists in Michigan.

Evidence suggests that provider factors such as intuition, experience, and medicolegal concerns as well as patient preference play key roles in driving the provision of low-value care, Dr Resnick said. “Financial incentives underlying the current health care system fail to discourage the delivery of imaging overuse from either the patient or provider perspective,” Dr Resnick said. “Nonetheless, as we transition to health care accountability and continue to assume increasing financial risk for the care we deliver, financial incentives will likely re-orient clinical practice towards minimizing overuse.”

Emergence of MRI

Meanwhile, amid hints and predictions of a decline in overuse of radiologic imaging for patients with low-risk PCa, magnetic resonance imaging (MRI), especially multiparametric MRI (mpMRI), appears to be emerging as a useful tool for managing this patient population. Dr Shore said he is starting to see a significant increase in the use of MRI for patients who have had a for-cause biopsy that was negative, but may require a second biopsy because of continued concern about the presence of cancer. “The evidence for using MRI is particularly good in that patient population,” he said.

Dr Hu said he believes MRI use will increase in part because of wider adoption of active surveillance as a management strategy for low-risk PCa. By enabling more accurate risk stratification, MRI can aid in the appropriate selection of men for active surveillance. After men are placed on active surveillance, MRI can be used to look for changes in cancerous tissue over time and to assist in deciding whether to perform repeat biopsy to monitor for cancer upgrading and upstaging. Dr Hu noted that during the 2004–2005 period looked at in his study, “MRI just was not that good for localizing and staging prostate cancer at that time.”

In addition, he predicts clinicians will order MRI scans more frequently prior to a first biopsy in men who have abnormal PSA values or digital rectal examination findings, with the goal of identifying suspicious lesions for a targeted biopsy. This approach has the potential for reducing the number of unnecessary prostate biopsies, as suggested by the PROMIS study.⁵ The study’s investigators showed that the use of mpMRI in men with elevated PSA might allow 27% of men to avoid primary biopsy and decrease the diagnosis of clinically insignificant cancer by 5%.