Abstract 38: Racial disparities in prostate cancer mortality rates explained by differences in dietary and lifestyle factors

Introduction: Black men have 2.1 times higher prostate cancer mortality rates than White men in the United States, yet the reasons for this disparity remain unclear. Several dietary and lifestyle factors may influence the risk of developing lethal prostate cancer. This study evaluated to what extent differences in the prevalence of modifiable risk factors by race could explain racial disparities in prostate cancer mortality.

Methods: Our study utilized data from the Health Professionals Follow-up Study (HPFS, N=51,529 men, 1986-2016) and the National Health and Nutrition Examination Study (NHANES, 2000-2010). First, we used data from NHANES to estimate the prevalence of three factors among Black and White men: smoking, vitamin D, and coffee. Then, using HPFS, we generated relative risk estimates for lethal prostate cancer for each factor. To estimate the relative prostate cancer burden associated with these risk factors, we calculated the population attributable fraction (PAF) for each factor by self-identified race, defined as the reduction in mortality that would be achieved if the population had been entirely unexposed, compared with the current exposure pattern. We then calculated the difference in the PAF between Black and white men to estimate the difference in mortality reduction between the two groups if all men had been entirely unexposed, assuming causality of risk factors and no effect modification by race.

Results: There were notable differences in the prevalence of several risk factors by race. For example, Black men had significantly lower levels of vitamin D[MLA1], were less likely to drink coffee, and had a higher prevalence of smoking compared to white men. We estimated that eliminating these risk factors among Black men could lead to a reduction in prostate cancer mortality that is 4-14% larger compared to eliminating these risk factors among white men.

Conclusions: Modifiable lifestyle and dietary factors are potentially responsible for a proportion of the racial disparity in prostate cancer mortality. Our future work will expand the modifiable factors as well as incorporating more contemporary comparisons of the prevalence of these factors to predict future disparities in prostate cancer.

Citation Format: Emily Rencsok, Michelle Sodipo, Travis Gerke, Konrad Stopsack, Lorelei Mucci. Racial disparities in prostate cancer mortality rates explained by differences in dietary and lifestyle factors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 38.

First look at patient reported outcomes from IRONMAN, the international registry of men with advanced prostate cancer

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Background: While population-based estimates of advanced prostate cancer survivors are lacking, an estimated 180,000 men in the US are living with metastatic prostate cancer. Their survivorship experience is distinct from localized patients as they suffer quality of life detriments both due to the severity of disease and its therapies. We examined quality-of-life indictors among men in the IRONMAN global registry of advanced prostate cancer. Methods: IRONMAN (International Registry of Men with Advanced Prostate Cancer) is a population-based prospective study of men with newly diagnosed advanced, metastatic hormone-sensitive (mHSPC) and castration-resistant prostate cancer (CRPC) enrolled from 16 countries. We report data from first 1865 men enrolled, 1567 who completed a baseline Patient Reported Outcome Measure (PROM) in the US (N=581), Canada (N=245), Spain (N=166), UK (N=204), Australia (N=126), Switzerland (N=88), Sweden (N=70), Ireland (N=46), and Brazil (N=41). PROMs are collected at baseline and every three months using electronic (90%) or paper versions of validated questionnaires. Results: The cohort includes 1,128 men with mHSPC and 737 with CRPC. Based on self-report, 9% of men overall (18% in the US) are Black and 83% are white (78% in the US). Sleep problems were common among men at enrollment, with 59% of men reporting problems with insomnia. The prevalence was similarly high among men with mHSPC or CRPC disease. Ten percent of men reported that pain substantially interfered with daily activities, and 24% reported pain had some effect. Physical functioning was high among both mHSPC (median 93.3, 80-100) and CRPC (median 86.7, 73.3-100) patients based on EORTC QLQ-30. Global health status was similar between the two groups (median 75, 58.3 - 83.3). More than 25% of men reported some cognitive impairment at baseline. Financial difficulties due to the disease and treatment were quite high, ranging from 12% in Sweden, 16% in Canada and Spain, 34% in the US, and 46% in Brazil. Conclusions: Men with advanced prostate cancer experience a range of quality of life detriments which impair overall health. While at baseline, many of these measures were similar among men with mHSPC and CRPC, we will continue to monitor these over time to examine changes in quality of life associated with disease progression and treatments. A longer-term goal is to identify opportunities for intervention to improve quality of life and potentially improve survival. Clinical trial information: NCT03151629.

IRONMAN: The international registry for men with advanced prostate cancer

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Background: Men with advanced prostate cancer (APC) experience high mortality and severely impacted quality of life due to the disease itself as well as its therapies, with Black men facing the highest disease burden. The treatment landscape for APC is rapidly changing; however, little is known about the real-life experience of men receiving new therapies. There is an urgent need to identify disparities in treatment patterns and outcomes in advanced disease, based on patient and country demographics. The International Registry for Men with Advanced Prostate Cancer (IRONMAN) is uniquely equipped to meet these needs. Methods: IRONMAN is a population-based prospective cohort of men with newly diagnosed metastatic hormone-sensitive (mHSPC) and castration-resistant (CRPC) prostate cancer aiming to enroll 5,000 men across 16 countries (Australia, the Bahamas, Barbados, Brazil, Canada, Ireland, Jamaica, Kenya, Nigeria, Norway, South Africa, Spain, Sweden, Switzerland, United Kingdom, Untied States). Patients are followed prospectively for overall survival, clinically significant adverse events, changes in cancer treatments, biomarkers, and Patient-Reported Outcome Measures (PROMs). Data is collected via longitudinal electronic questionnaires from patients and providers as well as blood samples and medical records. IRONMAN is currently enrolling in 10 countries at 103 sites. Sites were selected to create a diverse cohort across race/ethnicity, rural/urban populations, socioeconomic factors, and geographic regions. Of the first 1,865 men enrolled to date, 60% have mHSPC and 40% have CRPC; overall, 9% of men (18% in the US) self-identify as Black and 82% identify as white (78% in the US). 60% (N = 1,111) of this cohort has been enrolled outside of the US, and the median age at study entry is 70 years. The distribution and demographics of patients are continuously monitored to inform ongoing enrollment efforts. The IRONMAN Diversity Working Group meets monthly to discuss barriers and strategies to enhance enrollment of a racially and ethnically diverse population. The Low- and Middle-Income Country Working Group addresses the unique needs of men being recruited from the Caribbean and African sites in addition to supporting broad oncology efforts in these regions. These efforts support IRONMAN’s larger goal to investigate disparities in the care of patients with APC, having potential implications for decreasing racial disparities in survival outcomes. Clinical trial information: NCT03151629.

Abstract B022: Diversity of enrollment in prostate cancer clinical trials: Current status and future directions

Background: Prostate cancer incidence and mortality rates differ substantially by race and ethnicity globally and within the United States. Despite these disparities, many cancer clinical trials have a lack of representation of U.S. minority groups, and race is often overlooked when reporting trial results. The purpose of this study is to assess diversity of participants in prostate cancer clinical trials.

Methods: Available trials were identified through a systematic review of clinical trials using the U.S. National Library of Medicine's Clinical Trials Database and PubMed. Completed global phase III and phase IV clinical trials evaluating treatment, primary prevention, or screening of prostate cancer with published results were included in the analysis. Trials were analyzed for availability of race and ethnicity data and categories represented. Temporal and geographic trends were analyzed.

Results: Of the 61 treatment-based clinical trials analyzed, 39 (63.9%) reported race data. Twenty-one race categories were represented across the trials, with the largest categories being White (83.2% of participants), Black or African American (7.5%), other/not reported (4.4%), and Asian (2.7%). All other race categories represented less than 2% of participants each. Six trials (9.8%) additionally reported ethnicity data: 81.1% of participants with data were not Hispanic or Latino, 7.6% of participants were Hispanic or Latino, and 11.3% of participants did not indicate their ethnicity. Of four prevention-based trials, all had data available on race, but only one additionally reported ethnicity. The majority of participants in prevention trials were White (84.6%), with similar representation across race and ethnicity categories compared to the treatment clinical trials. Only one of the five screening trials had available race data, again showing majority White participants (85.0%). Categories unique to prevention and screening trials include Hispanic (non-African American), Hispanic (African American), non-Hispanic White, and non-Hispanic Black. The Swedish branch of the European Randomized Study for Screening for Prostate Cancer (ERSPC) reported country of origin rather than race data: 15% of participants were non-European. Additionally, diversity of participants has not changed over time, and representation of countries in trials is unequal.

Conclusions: More than one-third of prostate cancer clinical trials do not report race/ethnicity data. Moreover, there is significant variability in the race categories reported in trials, with 26 categories represented across the analyzed trials. Of the trials reporting race data, over 80% of participants were White. Current initiatives, such as the International Registry of Men with Advanced Prostate Cancer (IRONMAN), are aiming to recruit representative populations to decrease racial and ethnic disparities and ensure that men at risk for or diagnosed with prostate cancer are better represented in research and receive the best possible care.

Citation Format: Emily Rencsok, Latifa Bazzi, Rana McKay, Franklin Huang, Adam Friedant, Jake Vinson, Jelani Zarif, Stacey Simmons, Paul Villanti, Philip Kantoff, Elisabeth Heath, Daniel George, Lorelei Mucci. Diversity of enrollment in prostate cancer clinical trials: Current status and future directions [abstract]. In: Proceedings of the Eleventh AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2018 Nov 2-5; New Orleans, LA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(6 Suppl):Abstract nr B022.

5-alpha reductase inhibitors (5-ARI) and prostate cancer mortality among men with regular access to screening and health care

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Background: The excess risk of high-grade prostate cancer in the Prostate Cancer Prevention Trial (PCPT) among men randomized to finasteride raised concerns that a chemoprevention benefit would be offset by increased mortality. Two 2019 publications had contrasting results whether 5-ARIs increased prostate cancer mortality. In PCPT, there was no excess prostate cancer mortality. In a VA study, 5-ARI use was associated with later stage at diagnosis and 39% higher prostate cancer mortality risk. We studied men with regular access to health care and screening to address this conflicting evidence. Methods: We performed two parallel analyses in the Health Professionals Follow-up Study. 5-ARI use was reported on biennial questionnaires starting in 1996. In line with PCPT, we studied 38,047 men for cancer incidence and mortality through 2016. In line with the VA study, we undertook a case-only study of 4,225 patients with localized/locally advanced cancers followed similarly. We estimated hazard ratios (HR) and 95% confidence intervals accounting for screening patterns, lifestyle factors, and concomitant medications. Results: 5-ARI ever-users (n = 4,101; 10.7%) were more likely to have had regular PSA screening (74% vs. 57% nonusers) and a negative prostate biopsy before diagnosis. Neither ever 5-ARI use (HR 1.08, 0.73-1.60, 445 events) nor long-term use ( > 4 years, HR 1.03, 1.03-2.02) were associated with lethal prostate cancer. There was no difference in stage. Diagnostic PSA levels were lower in 5-ARIs users (10.0 vs. 16.0 ng/ml in never-users). Among nonmetastatic cases, 278 men died of prostate cancer; there was no association between 5-ARIs and prostate cancer survival (HR 0.85, 0.51-1.43). Conclusions: Our results align with PCPT and show no excess risk of lethal prostate cancer, no higher stage at diagnosis, and no excess mortality after diagnosis associated with 5-ARI. Men on 5-ARIs had more interactions with health care, which may have led to higher quality care. This contrasts with the VA study where men on 5-ARIs were diagnosed later due to suppressed PSA and had worse survival. These results show the importance of real-world data in framing the benefits and risks associated with 5-ARIs.