Inappropriate Imaging in Both Breast and Prostate Cancer

Roxanne Nelson

March 12, 2015

At a regional level, inappropriate imaging rates for breast cancer are associated with inappropriate imaging rates for prostate cancer, according to new data.

In other words, a man with prostate cancer has higher odds of undergoing inappropriate imaging if he lives in a region with higher rates of inappropriate breast cancer imaging, and to a lesser extent, vice versa.

The finding is published online in JAMA Oncology.

Using the Surveillance, Epidemiology, and End Results (SEER) Medicare-linked database, the authors identified 9219 men with prostate cancer and 30,398 women with breast cancer, and found high rates of inappropriate imaging overall, for both prostate cancer (44.4%) and breast cancer (41.8%).

They also analyzed the data at both the patient level and hospital referral regions (HRR) level. An HRR represents a predefined regional market for tertiary healthcare at a major regional referral hospital.

At the HRR level, inappropriate prostate cancer imaging rates were associated with inappropriate breast cancer imaging rates (P = .35; P < .01).

When looking at the patient level, women with breast cancer were more likely to undergo resource-intensive imaging than were men with prostate cancer. The rates of breast cancer imaging more strongly influenced patient-level prostate cancer imaging (statistically significant) than vice versa (positive association, but not significant).

The authors note that this is a novel finding, in that utilization of healthcare resources across diseases may be determined by regional-level factors.

Driven By Regional Differences

"A lot of the policy efforts to combat inappropriate imaging have focused on the individual patient and physician," said lead author Danil V. Makarov, MD, MHS, an assistant professor in the department of urology and the department of population health at New York University School of Medicine. "Different guidelines and initiatives like Choosing Wisely call for shared decision making between patients and physicians."

There are significant associations between geography and variations in healthcare utilization in the US, which have been observed in prior studies. But because prostate and breast cancer patients are a nonoverlapping cohort that is treated by nonoverlapping specialists, an association of inappropriate imaging between them suggests that regional culture and infrastructure contribute to healthcare utilization patterns across diseases, note the authors.

Wide regional imaging variations specifically for prostate cancer have been documented. In an interview, Dr Makarov explained that his group has focused on inappropriate imaging in prostate cancer, and large variations can't entirely be explained by regional differences in patient-level characteristics.

"But if the regional variation was just the result of randomness, and you took two separate populations like breast and prostate and looked at regional rates, there shouldn't be a correlation," he said. "So we hypothesized that if there was something driving inappropriate regional differences in prostate cancer, it might also be driving inappropriate rates in breast cancer and we found that they were correlated."

Inappropriate Prostate and Breast Cancer Imaging Correlate

Choosing Wisely is a national effort that encourages the appropriate use of healthcare resources, and as part of that campaign, the American Society of Clinical Oncology (ASCO) released a "Top 5" list of tests and procedures that could be used less without compromising care.

ASCO's list <a href="recommends decreasing the use of imaging to stage patients with low-risk prostate and breast cancers. But despite these recommendations, the practice continues to persist, and imaging is frequently offered to patients with early stage disease.

Dr Makarov and colleagues conducted a retrospective cohort study using the SEER Medicare database to determine whether regional rates of inappropriate prostate and breast cancer imaging were associated.

Patients included in the cohort were diagnosed (2004 to 2007) with low-risk prostate (clinical stage, T1c/T2a; Gleason score, ≤ 6; prostate-specific antigen level, < 10 ng/mL) or breast cancer (in situ, stage I, or stage II disease), based on definitions from Choosing Wisely.

In their HRR-level analysis, the dependent variable was HRR-level imaging rate among patients with low-risk prostate cancer, and independent variable was HRR-level imaging rate among patients with low-risk breast cancer.

For the subsequent patient-level analysis, a multivariable logistic regression was used to model prostate cancer imaging as a function of regional breast cancer imaging and vice versa.

The authors found that men aged 80 to 84 years were the most frequent recipients of inappropriate imaging for prostate cancer (49%), while women aged 67 to 69 years were most frequently imaged inappropriately for breast cancer (44%). In both groups, patients with the most comorbidities experienced the most imaging (50%for both).

Race, year of diagnosis, median household income, or marital status were not associated with imaging frequency in men, but they were in women.

Patients with prostate cancer underwent more inappropriate imaging than those with breast cancer, but breast cancer patients had a higher rate of PET scans (7.0% vs 0.3%).

In addition, the authors also found that HRR-level CT and bone-scan use and HRR-level bone-scan use across prostate and breast cancers were positively correlated (Pearson coefficients of 0.27 [P = .01] and 0.19 [P = .09], respectively).

In the multivariable model, a prostate cancer patient underwent inappropriate imaging 34.2%, 44.6%, 41.1% and 56.4% of the time if he lived in the first, second, third, and fourth quartiles of HRR-level inappropriate breast cancer imaging.

Similarly, in the first, second, third, and fourth quartiles of prostate cancer imaging, inappropriate breast cancer imaging was 38.1%, 38.4%, 43.8%, and 45.7%, respectively.

Caution Suggested When Moving Forward

While these observed regional-level associations across diseases provide further evidence suggesting that factors within an HRR drive variations in healthcare utilization regardless of clinical context, the authors of an accompanying editorial caution that it is important to "distinguish inappropriate use of low-value care from the related but distinct issue of excess geographic variation in health care utilization."

"Although the existence of excess variation in health care spending without improvement in patient outcomes suggests that inappropriate utilization may be a primary explanatory factor, prior studies have indicated that only a small proportion of observed geographic variation in health care spending can be explained by inappropriate use," write Samuel Swisher-McClure, MD, MSHP and Justin Bekelman, MD, both from the University of Pennsylvania, Philadelphia.

And as alluded to in the current paper, regions of high spending tend to have higher rates of both appropriate and inappropriate care, the editorialists point out, while lower-spending regions have lower rates of both appropriate and inappropriate care.

"If correct, it might suggest that policy interventions targeted at the regional level must be designed with extreme care, lest they reduce utilization of appropriate care for patients who need it along with intended reductions in inappropriate care," they say.

The current paper does suggest that the overuse of low-value imaging tests among cancer patients may be driven by factors within geographic regions, but despite extensive study, these factors are not well understood, and how they contribute to overuse of inappropriate care, write Drs Swisher-McClure and Bekelman.

Dr Makarov agrees. "This is purely hypothesis generating and these findings are not ready for prime time," he told Medscape Medical News.

Much more work is needed to put these findings into better context, he noted. "We need to figure out what is going on, and maybe confirm these findings to other disease states."

Qualitative exploration may also be needed, which would include interviewing patients and physicians, to find out how to better characterize regional differences. "It is likely that different factors are influencing care in different regions," he noted. "Unfortunately, there isn't a database where you can sit down and crunch numbers, you have to roll up your sleeves and talk to the people on the ground who are making these decisions."

The study was supported by the Robert Wood Johnson Foundation, the Louis Feil Charitable Lead Annuity Trust, and the US Department of Veterans Affairs, Veterans Health Administration, Health Services Research & Development Service. Coauthor Joseph Ross receives research support from the Centers for Medicare & Medicaid Services and from the US Food and Drug Administration, and is also supported by a grant from the National Institute on Aging and by the American Federation for Aging Research through the Paul B. Beeson Career Development Award Program.

Dr Makarov is a consultant for Castlight Health and for the US Food and Drug Administration. Coauthor Cary Gross is a consultant for Johnson & Johnson, Medtronic, and 21st Century Oncology, and receives research support through Yale University from Medtronic and Johnson & Johnson to develop methods of clinical trial data sharing. The editorialists disclosed no relevant financial relationships.

JAMA Oncology. Published online March 12, 2015.

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