Are there racial and ethnic disparities in the use of novel hormonal therapy agents in men with advanced prostate cancer?

In a recent study published in JAMA Network Open, researchers assessed ethnic and racial differences in novel hormonal therapy (NHT) use among advanced prostate cancer (PCa) patients.

Background

NHT agents have prolonged overall survival in randomized clinical trials for PCa patients. Androgen signaling modulations are crucial in treating advanced PCa. Androgen deprivation treatment (ADT) involves using gonadotropin-releasing hormone agonists or antagonists to lower androgen levels in circulation.

Agents antagonizing androgen receptor (AR) action of the second generation, such as darolutamide, enzalutamide, and apalutamide, can improve AR affinity and specificity more effectively than those of the first generation. NHT agents, in combination with ADT can effectively suppress androgen-based signaling.

However, their usage in a population is unclear, especially in terms of impartial access to medications across racial and ethnic groups.

About the study

In the present cohort study, researchers investigated whether there were racial and ethnic disparities in NHT among male PCa patients.

The study used 2020 Surveillance, Epidemiology, and End Results (SEER) data linked to Medicare. The researchers included males diagnosed with de novo advanced PCa between 1 January 2011 (the initial year of abiraterone authorization by the United States Food and Drug Administration (US FDA) and 31 December 2017 (the final year for diagnosis linked to the SEER database).

PCa was classified as high-risk of localized metastasis (N0M0), regional metastasis (N1M0), or distant metastasis (M1) using the Systemic Therapy in Advancing or Metastatic Prostate Cancer: Evaluation of Drug Efficacy (STAMPEDE) criteria. Participants had to have a known follow-up duration, Medicare Part A and Part B cover, and Part D participation at diagnosis. The participants were required to start ADT within six months of being diagnosed.

The study exposures were ethnicity and race [non-Hispanic black, Hispanic, white, or belonging to other races and ethnicities (American Indian, Alaskan Native, Pacific Islander, Asian, or unknown] abstracted from the SEER data fields. The primary study outcome was NHT administration (enzalutamide, abiraterone, darolutamide, or apalutamide) measured through 31 December 2019 (the most recent follow-up data for the SEER database).

The data were analyzed between January and May 2023. Other variates included disease characteristics and patient factors. The team used the time-to-event method to analyze NHT use, calculating cumulative incidence from initial cancer diagnosis until NHT administration. Mortality without NHT use was considered a competitive event. The researchers accounted for Part D cover loss.

Results

In total, 3,748 males were included; the median participant age was 75 years. The study population comprised 8.0% (n=312) black individuals, 7.0% (n=263) Hispanic individuals, of which 78% (n=2,923) were white, and 7.0% (n=250) belonged to other races and ethnicities. Among the participants, stage cancer [57% (n=2,135) suffered from M1, 29% (n=1,095) were diagnosed with N0M0, and 14% (n=518) with N1M0 cancer.

In total, 36% (n=1,358) of patients received one or more NHT drugs. Among the participants, 61% (n=825) received Abiraterone, 38% (n=514) received enzalutamide, and 1.0% (n=19) received apalutamide or darolutamide as their initial NHT drug. The participants were followed for four years (median). White participants showed the highest two-year novel hormonal therapy usage (27%), followed by Hispanics (25%) and those belonging to other races or ethnicities (23%).

Black individuals showed the least NHT utilization (20%). The significantly lower rate of NHT usage among black individuals compared to their white counterparts persisted even after five years (37% vs. 44%). However, there were no significant differences in NHT use between white and Hispanic participants or those belonging to other races and ethnicities (e.g., five years: Hispanic participants: 38%; those belonging to other races and ethnicities: 41%).

In the subgroup analysis, patterns of lower NHT use by black individuals persisted among M1 cancer patients (e.g., vs. white participants at five years: 51% vs. 55%) and those at risk of N0M0 cancer (e.g., vs. white participants at five years: 12% vs. 23% disease). In the multivariate analysis, black participants continued showing significantly lower likelihoods of initiating NHT after disease, patient, and sociodemographic adjustments [adjusted sub-distribution hazard ratio (SHR) of 0.8].

There were no significant differences for Hispanic participants compared to white participants (adjusted sub-distribution hazard ratio, 0.99) or for participants belonging to other races and ethnicities compared to white participants (adjusted sub-distribution hazard ratio, 0.91). Individuals of white race, lower age, Gleason scores of 9.0 and 10, M1 cancer, elevated prostate-specific antigen (PSA) levels, less comorbidities, better socioeconomic status, and married status were more likely to receive NHT.

Conclusion

Overall, the study findings showed that Medicare beneficiaries with advanced prostate cancer received NHT agents less uniformly by race, with black participants showing decreased use compared to other racial and ethnic groups. The findings indicate multifactorial barriers to racially equitable NHT administration. Future research is required to address these disparities.

Written by

Pooja Toshniwal Paharia

Dr. based clinical-radiological diagnosis and management of oral lesions and conditions and associated maxillofacial disorders.