Current disparities in the treatment of prostate cancer with targeted therapies across the US— and ways in which this might be affected by advanced technologies, as well as means by which the disparity gap might be closed— were addressed at the 2022 ASCO Genitourinary Cancer Symposium by Kosj Yamoah, MD, PhD, Section Head for Genitourinary Radiation Oncology and Director for Radiation Oncology Health Disparities Research at Moffitt Cancer Center, Tampa, FL.¹

Dr Yamoah noted that data from a retrospective study of the state of prostate cancer among men undergoing routine care in US Veterans Affairs (VA) hospitals between 2005 and 2019 showed a higher incidence of prostate cancer, as well as morbidity and mortality in African Americans compared with White men.² These findings were particularly important, given that the VA is the only US system where access to care is near equal in the sense that patients do not have to pay for their healthcare, Dr Yamoah stressed.

Consistent with US population-level data, the incidence of both localized and de novo metastatic prostate cancer was 2-fold greater among African American veterans, despite similar if not better routine screening and utilization of imaging for African American men within the VA system, Dr Yamoah pointed out. This pattern remained consistent in almost every individual state.

Emerging data from clinical trials show that treatment response rates are identical in African American and White men, Dr Yamoah noted. Nonetheless, in the VA cohorts, an increased risk through a nearly 2-fold racial disparity in metastasis persisted across National Comprehensive Cancer Network (NCCN) risk groups (low, intermediate, high) between African American and White veterans. This translated into a higher prostate-cancer specific mortality.

Prostate Cancer in African American Men

The overall higher prostate cancer-specific mortality in African Americans, compared with White men, is a result of a complex interplay between differences in incidence, adverse clinical presentation, and suboptimal treatment delivery, as well as treatment response, Dr Yamoah stressed.³ Multiple complex etiologies likely to influence the biological process of prostate cancer include:

• inherited genetics
• genomics
• immunity
• environmental/occupational exposures
• epigenetics
• stress
• diet
• metabolism

Other factors that constantly impact access to care and care delivery include structural racism, health policies, patient mistrust, and access to health insurance.

Dr Yamoah stressed the need for equity in healthcare, i.e., equal access and equal treatments for equal outcomes. He explained that whereas equality is the process of giving all people the same access to treatment, equity recognizes that even if everything is equal, some people will still be disadvantaged. However, neither equality nor equity are present, Dr Yamoah stressed.

Few data are available on disparities in access to therapy for theranostics in advanced prostate cancer, Dr Yamoah acknowledged. The data available on the use of prostate-specific membrane antigen (PSMA) radioligands come from imaging studies. Investigators at the University of California, San Francisco (UCSF) evaluated the demographic differences between patients receiving ¹⁸F-fluciclovine or ⁶⁸Ga-PSMA-11 for biochemically recurrent prostate cancer at a single tertiary medical center between October 2015 and January 2020.⁴ Unusually, for a study with a new agent, imaging was performed under a cost-recovery mechanism, meaning that the patient or insurance companies had to cover the cost of the agent, estimated at $900-$1400.

Data from this study showed that Black patients were more likely to be classified as lower and less likely to be classified as higher socioeconomic status, compared with non-Hispanic White patients. Overall, Black patients were 4 times more likely to receive ¹⁸F-fluciclovine scans than ⁶⁸Ga-PSMA-11 scans. The study showed that access to ⁶⁸Ga-PSMA-11 s through clinical trials was severely limited for Black patients. Older patients and those with government insurance were more likely to have imaging with ¹⁸F-fluciclovine, which, unlike ⁶⁸Ga-PSMA, is covered by both government and commercial payers, Dr Yamoah noted.

Some of the problems identified in the UCSF study were addressed by Dr Yamoah and colleagues in VanDAAM (Validation Study on the Impact of Decipher Testing) (NCT02723734), a prospective study that sought to determine whether the Decipher prostate cancer test (Veracyte) could predict aggressive prostate cancer with the same accuracy in African American men as in non-African-American men in whom the test was developed. The investigators actively recruited participants with low-or intermediate-risk prostate cancer to achieve a 1:1 enrollment ratio of African American to non-African American men by first accruing low risk African-American participants and then enrolling matching non-African-Americans based on prostate specific antigen (PSA) at diagnosis. Patients subsequently received standard of care treatment with either radiotherapy or surgery. Those classified as high risk by Decipher went on to PSMA-PET imaging over the following 5 years in an attempt to identify early triggers for metastatic disease.

Early results showed that among the patients enrolled with low-risk disease (NCCN stratification), 18.2% of African Americans were reclassified as high risk on Decipher testing compared with 0% of non-African Americans. Fewer African American patients had adequate follow-up, even though patients were all on similar protocols, Dr Yamoah reported. In addition, a greater proportion of African American patients identified at high risk by Decipher declined PSMA-PET imaging.  More effort is needed to ensure that African American patients gain trust in clinical trialists, Dr Yamoah commented.

Addressing Prostate Cancer Disparities

One of the lessons learned from the conduct of research is that equitable access to precision imaging and treatment can close the disparity gap and lead to improved outcomes, Dr Yamoah concluded. Even when ensuring equality of access, however, African American men are less likely to participate in clinical trials of novel therapies or in advanced imaging-based studies. Following treatment, African American men are less likely to follow-up with precision imaging that may lead to delay in detection of recurrence.

A number of actions are needed to close this disparity gap, Dr Yamoah explained. “Every one of us needs to spend a little more time speaking with our patients and helping them make decisions for clinical trial participation,” he urged. Working with patient advocates is imperative, he stressed. Acknowledging that this may be time-consuming, he emphasized the need for follow-up with patients, whatever type of treatment they are receiving. He added that major barriers such as insurance coverage, cost of care, and other financial considerations need to be addressed when designing clinical trials to improve access to precision imaging.

References

1. Yamoah K. Challenges and opportunities in delivering novel therapies: the diversity and inclusion perspective. Presented at 2022 ASCO Genitourinary Cancers Symposium, February 17-19, San Francisco, CA & online.
2. Yamoah, Lee KM, Awasthi S, et al. Racial and ethnic disparities in prostate cancer outcomes in the Veterans Affairs health care system. JAMA Netw Open. 2022;5(1):e2144027. DOI: 1001/jamanetworkopen.2021.44027
3. Mahal BA, Gerke T, Awasthi S, et al. Prostate cancer racial disparities: a systematic review by the Prostate Cancer Foundation Panel. Eur Urol Oncol. 2022;5(1):18-29. DOI: 1016/j.euo.2021.07.006
4. Bucknor MD, Lichtensztajn DY. Lin TK, et al. Disparities in PET imaging for prostate cancer at a tertiary academic medical center. J Nucl Med. 2021;62(5):695-699. DOI: 2967/jnumed.120.251751