Assessing Medicare data from millions of diagnostic exams, researchers found the number of advanced oncologic imaging scans performed in academic practices doubled between 2004 and 2016. The share of oncologic imaging in nonacademic, community settings, however, was not as high. Furthermore, the frequency of diagnostic oncologic imaging on the state levels appears to correlate with radiologist supply rather than prevalence of cancer.

The findings, the researchers say, indicate a lack of adherence to cancer imaging guidelines and a potential worsening of disparities in the exposure and familiarity radiologists have in performing oncologic imaging exams. Such issues could create challenges in maintaining high-quality oncologic imaging throughout the whole practice of radiology.

"The lack of cancer imaging experts in community settings is closely related to the shortage and limited geographic distribution of oncologists and other specialists in cancer care in the United States," study author Dr. Hedvig Hricak, chair of the department of radiology at Memorial Sloan Kettering Cancer Center, told HCB News. "Accurate, clinically relevant interpretation of oncologic imaging requires an understanding of cancer biology, an awareness of the clinical questions that need to be answered to choose from growing numbers of treatment options, and the ability to recognize and assess the effects of various treatments. Thus, the development and maintenance of expertise in cancer imaging requires consistent involvement in team-based, multidisciplinary cancer care."

Radiologists with subspecialized expertise are concentrated mainly on the two coasts and, to an extent, in the middle of the country. Redistribution of these physicians geographically would not be enough to meet demand, according to Hricak, who says that it "stands to reason that where oncologists and other specialists in cancer care are lacking, radiologists with cancer imaging expertise are bound to be lacking as well."

The study is the first, to the authors' knowledge, to use a national claims database to quantify oncologic diagnostic imaging exams. The group examined and compared a national sample from the CMS 5% Carrier Claims Research Identifiable Files of more than five million Medicare claims submitted in 2016 to a similar number from 2004. Oncologic imaging represented 3.9% of the total sample in 2004, and increased to 4.3 % in 2016. Advanced cancer imaging included CT, MR and PET/CT, and accounted for 10.8% and 9.5% of imaging, respectively.

Approximately two-thirds of oncologic imaging was performed in non-academic practices in 2016, aligning with data from the National Cancer Institute that indicates that the majority of cancer care takes place in community settings. The share of imaging that was oncologic, however, was higher in academic than in nonacademic practices, and in physician offices and hospital outpatient offices, compared to inpatient or ED settings.

The authors also observed geographic discrepancies in percentages of advanced oncologic imaging, with Arkansas holding the highest rate at 15.3% in 2016, while Wyoming had the lowest at 4.9%. Utilization was highest in Washington, D.C. at 162 exams per 1,000 Medicare beneficiaries and again, lowest in Wyoming, at a rate of 25 per 1,000.

The share of advanced imaging that was oncologic varied by state and did not correlate with geographic variations in cancer prevalence or radiologist supply. While state-level utilization of oncologic advanced imaging also did not correlate with cancer prevalence, it did do so significantly with radiologist supply.

Among the authors’ suggestions for addressing these issues is the creation of physician networks that can provide second opinions; and the creation of some form of accreditation or certification, as well as maintenance-of-certification pathways. They also encourage greater investment in AI and telemedicine technologies for mentoring and peer learning.

"The incidence of cancer in the United States is rising, and while improvements in cancer care have reduced overall cancer mortality, not all populations are benefiting equally," said Hricak. "Outcomes vary substantially depending on the care setting and patients' insurance status, race and ethnicity, with many patients not receiving the care recommended by national guidelines. Artificial intelligence and telemedicine will help tremendously by improving the implementation of guidelines for imaging and treatment, streamlining patient workflow, assisting with rapid and accurate image interpretation, and making it easier to get second opinions and consultations. For improving cancer care in rural areas, telemedicine will be absolutely essential."

The findings will be published in the Journal of the American College of Radiology.