ASCO 2021: Differences in the Pattern of and Response to Treatment: Not Just Race

(UroToday.com) As part of the 2021 American Society of Clinical Oncology (ASCO) Annual Meeting's session entitled “Evolution of Disparities in Prostate Cancer Treatment: Is This a New Normal?” Dr. Elisabeth Heath discussed differences in prostate cancer patterns and response to treatment, beyond racial differences.


She began by emphasizing that there are meaningful disparities in prostate cancer outcomes and treatment, due to race, ethnicity, geographic location, financial status, and socioeconomic status through their influence on treatment decision making.

Beginning with localized disease, she highlighted data from the National Cancer Database among 214,972 men with high-risk prostate cancer diagnosed between 2004 and 2016. Utilization of prostatectomy, compared to radiotherapy, was associated with higher income, private insurance, and treatment at an academic center. Black men were less likely to undergo radical prostatectomy though, over time, this difference is diminishing.

However, among men who undergo radical prostatectomy, Black men have a 20% higher mortality than white men while Asian men have a 35% lower mortality than white men. These disparities are actually greatest among those without comorbidities and those with less aggressive disease (early-stage and low-grade disease). For example, among men with Gleason 6 prostate cancer, Black men are twice as likely to die of prostate cancer compared with non-Black men. However, these data are limited by a lack of data on recurrence, cause of death, and short follow-up time.

Radiotherapy is used more commonly among Black men than Hispanic or white men. However, among those who are treated with radiotherapy, rates of non-completion were higher among Black men. However, the use of SBRT may be able to diminish these disparities.

Beyond race, we need to consider the effect of ethnicity. There are meaningful differences in cancer rates among Hispanic populations. Further, it is important to distinguish Hispanic populations (who descend from Spanish speaking countries, such as Mexico) and Latino groups (who descend from Latin American countries, such as Brazil).

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Beyond race and ethnicity, Dr. Heath emphasized the importance of rurality. Even when stratified by disease risk, rural residents are much less likely to receive treatment. Further, cancer survivors in rural regions have a lower quality of life and thus have a greater need for supportive interventions to increase physical, social, and emotional quality of life.

Interestingly, she highlighted that there is no difference in treatment disparities for minorities and uninsured patients between academic and community centers: Black, Hispanic, and uninsured patients remain less likely to receive definitive therapy. Highlighting the example of access to advanced molecular imaging, Black patients at an academic center had nearly 4 fold lower access to these modalities.

She then transitioned to discussing the effects of socioeconomics. Even in the Geneva Cancer Registry wherein there is widespread access to high-quality care, patients of low socioeconomic status have a two-fold higher risk of death compared to those with high socioeconomic status.

Dr. Heath then highlighted the importance of guidelines: she presented data from the VA assessing the effect of PSA testing guidelines from the USPSTF. In this context, veterans of different races had similar rates of PSA screening, highlighting that guidelines can be successfully implemented within specific systems.

She then moved to discuss the effect of race on cancer treatment, emphasizing a wealth of data suggesting that Black men with prostate cancer have equal or better treatment response when compared to white men. She first highlighted data regarding sipuleucel-T. In the PROCEED multi-center, open-label, observational registry, Black men had significantly improved survival compared to white men (HR 0.70, 95% CI 0.57-0.86 in PSA-matched men and HR .81, 95% CI 0.68-0.97 among all patients). Further, a meta-analysis of 10 phase III trials of docetaxel in men with mCRPC has demonstrated that Black men have a statistically significantly lower risk of death, compared to white men, in the context of receiving similar care (HR 0.81, 95% CI 0.72-0.91). Similarly, a retrospective review of men treated with radium-223 in the VA system demonstrated that Black race was associated with a decreased risk of mortality (HR 0.75, 95% CI 0.57-0.99) despite more advanced disease at the time of treatment initiation. A comparison of outcomes among patients treated with abiraterone similarly shows that Black men have a greater response to therapy (measured by the proportion of patients with PSA decline) and longer median PSA-based progression-free survival (16.6 months vs 11.5 months). Interestingly, in a comparison between enzalutamide and bicalutamide in first-line mCSPC, 7-month PSA response rates were comparable for Black and white men who received enzalutamide (93% vs 94%) while rates were much lower among Black men who received bicalutamide (42 vs 86%). She highlighted that, based on claims data, the use of first-generation anti-androgen in this disease space is relatively common (23-38% depending on the treating physician). Thus differential practice patterns may account for differential outcomes.

Dr. Heath then discussed disparities in clinical trial enrollment. Nationwide, 6.2% of clinical trial participants are African American, substantially lower than the proportion in the general population or among cancer patients. In addition, in prostate cancer, Latino and Asian men are also under-represented. Further, only 12% of the sample in the TCGA are from African Americans, thus limiting the ability to provide generalizable genomic data. Globally, the data are no better: among 72 global phase III and III prevention, screening, and treatment trials in prostate cancer from 1987 to 2016, 96% of enrolled men were white. Further African countries and Caribbean countries were under-represented. Currently, the IRONMAN registry is an ongoing effort to include men with advanced prostate cancer across many countries, with the aim to provide information on treatment, side effects, and care delivery.

However, among patients who are included in clinical trials, a number of publications have demonstrated that there are no significant differences in progression-free survival or overall survival on account of patient race.

She then highlighted the PACCT (Partnering Around Cancer Clinical Trials), a multilevel intervention to increase the participation of African Americans in prostate cancer. This is a multilevel, multi-site intervention addressing patients and physicians. Based on preliminary analyses, the authors found that even at major research centers, most eligible patients do not receive a trial offer. Further, there is a higher level of medical suspicion in Black men which underpin differences in willingness, highlighting the importance of interventions to building trust in medical institutions. She then highlighted a model that we, as physicians and providers, may utilize.

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At the National Cancer Institute, the Geographic Management of Cancer Health Disparities Program seems to foster collaboration, resource-sharing, capacity building across 7 regions to improve health disparities. Further, the NCI has established that National Outreach Network to enhance the NCI’s cancer health disparities research and to disseminate culturally appropriate, evidence-based cancer information.

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Presented by: Elisabeth I. Heath, MD, FACP, Karmanos Cancer Center, Detroit, MI

Written by: Christopher J.D. Wallis, Urologic Oncology Fellow, Vanderbilt University Medical Center Contact: @WallisCJD on Twitter at the 2021 American Society of Clinical Oncology (ASCO) Annual Meeting, Virtual Annual Meeting #ASCO21, June, 4-8, 2021
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