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May 12, 2022
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As proton beam therapy use for cancer increased, ‘so did the racial disparity in receipt’

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Use of proton beam therapy increased significantly among patients with cancer in the U.S. between 2004 and 2018, but Black individuals had a lower likelihood of receiving the therapy than their white counterparts.

Perspective from J. Isabelle Choi, MD

Researchers presented the findings of two cross-sectional studies in JAMA Network Open.

Proportion of patients who received proton therapy.
Data derived from Nogueira LM, et al. JAMA Netw Open. 2022;doi:10.1001/jamanetworkopen.2022.8970.

Rationale and methods

Proton beam therapy can deliver a higher dose of radiation to the tumor with less damage to surrounding healthy cells,” Leticia M. Nogueira, PhD, MPH, senior principal scientist in the surveillance and health services research program at American Cancer Society, told Healio. “Therefore, proton beam therapy is potentially superior to photon-based radiation therapy to treat tumors with complex anatomy, surrounded by sensitive tissues, or for treating childhood cancer, where long-term side effects of radiation therapy are a main concern. However, proton beam therapy can cost twice as much as photon-based radiation therapy.”

In the first study, Nogueira and colleagues examined the overall patterns of use of proton beam therapy according to the American Society for Radiation Oncology’s U.S. clinical indications. Researchers divided patients into two groups: Group one included those for whom proton beam therapy is recommended and group two included those for whom evidence of proton beam therapy efficacy is still under review.

In the second study, researchers assessed whether racial disparities exist in the receipt of proton beam therapy between Black and white individuals. The cross-sectional study included 5,225,929 patients (mean age, 63.2 years; 86.4% white and 13.6% Black; 54.3% women) included in the National Cancer Database eligible to undergo proton beam therapy for various cancer types between 2004 and 2018.

Researchers used propensity score matching to ensure comparability of Black and white patients’ clinical characteristics and regional availability of proton beam therapy per the National Academy of Medicine’s definition of disparities.

Key findings

Results of the first study showed use of proton beam therapy in the U.S. increased overall for all new cancer diagnoses — from 0.4% in 2004 to 1.2% in 2018 (annual percent change [APC], 8.12; P < .001).

Researchers reported significant increases (P < .001) in group one from 2010 to 2018 (0.4% to 2.2%; APC = 21.97) and in group two from 2014 to 2018 (0.03% to 0.1%; APC = 30.57). In group two, they observed the largest increases between 2010 and 2018 in proton beam therapy targeted to the breast (0% to 0.9%; APC = 51.95) and to the lung (0.1% to 0.7%; APC = 28.06; P < .001 for both). The only decrease in use occurred in prostate cancer between 2011 and 2014 (1.4% to 0.8%; APC = 16.48; P = .03); however, use for this cancer site rebounded to 1.3% in 2018 (APC = 12.45; P < .001).

The second study revealed Black patients had a lower likelihood than white patients of receiving proton beam therapy (0.3% vs. 0.5%; OR = 0.67; 95% CI, 0.64-0.71).

In addition, researchers observed increased racial disparities among those included in group one (0.4% vs. 0.8%; OR = 0.49; 95% CI, 0.44-0.55) compared with those in group two (0.3% vs. 0.4%; OR = 0.75; 95% CI, 0.7-0.8). The disparities observed among group one patients increased throughout time (APC = 0.09; P < .001), with the greatest increase observed in 2018.

Researchers also found patients in group one most likely to have private health insurance (55.4%) during 2018, whereas most of those in group two had Medicare (52.5%).

Leticia M. Nogueira, PhD, MPH
Leticia M. Nogueira

“Of note, the racial disparity in receipt of proton beam therapy was greatest for the two most common U.S. childhood cancers — rhabdomyosarcoma and central nervous system cancers. Matching on socioeconomic status or health insurance coverage type did not eliminate these disparities,” Nogueira said. “As the number of facilities offering proton beam therapy in the U.S. increased, so did the racial disparity in receipt of proton beam therapy. Therefore, increasing availability of therapeutic advances without addressing structural determinants of racial disparities can worsen, instead of ameliorating, racial disparities in receipt of quality cancer treatment.”

Implications

Black individuals continue to have worse access to quality cancer care in the U.S., and modifiable factors, other than availability of new therapeutic options, need to be addressed to eliminate racial disparities in cancer care and outcomes, Nogueira said.

“Future research should evaluate the contribution of oncology referral patterns, provider intrinsic bias and institutions’ policies and practices, such as provision of transportation services and clinical trial enrollment practices, to racial disparities in receipt of quality cancer care,” she added.

References:

Nogueira LM, et al. JAMA Netw Open. 2022;doi:10.1001/jamanetworkopen.2022.8970.
Nogueira LM, et al. JAMA Netw Open. 2022;doi:10.1001/jamanetworkopen.2022.9025.

For more information:

Leticia M. Nogueira, PhD, MPH, can be reached at American Cancer Society, 250 Williams St., Atlanta, GA 30067; email: leticia.nogueira@cancer.org.