Racial disparities in utilization and effectiveness of first-line therapies in metastatic castrate-resistant prostate cancer.

Authors

null

Mallika Marar

University of Pennsylvania, Philadelphia, PA

Mallika Marar , Ronac Mamtani , Vivek Narayan , Neha Vapiwala , Ravi Bharat Parikh

Organizations

University of Pennsylvania, Philadelphia, PA, Harvard Medical School, Boston, MA

Research Funding

No funding received
None

Background: Prospective evidence suggests that abiraterone use is associated with improved progression-free survival in African-American (AA) men with metastatic castrate-resistant prostate cancer (mCRPC) compared to white men. It is unclear whether race-based differences in treatment utilization and effectiveness exist for men with newly diagnosed mCRPC treated in real-world clinical practice. Methods: In this retrospective cohort study, we used the Flatiron Health electronic health record-derived de-identified database to identify patients with mCRPC who received first-line (1L) systemic therapy between 2012 and 2018. We used multivariable logistic regression analysis to examine differences in utilization of abiraterone, enzalutamide, and docetaxel between AA and white men. We then used Fine-Gray models with death as a competing risk to assess treatment-specific associations between race and time to next therapy (TTNT) – a proxy for progression-free survival. Finally, we used multivariable Cox proportional hazards analyses to assess for treatment-specific racial disparities in all-cause mortality. All analyses were adjusted for age, Elixhauser comorbidity index, baseline steroid or opioid use (a proxy for disease aggressiveness), performance status, insurance status, and (if significant) an interaction term for race and age. Results: Of 3,808 mCRPC patients in the cohort, 2,165 (68.7%) were white and 404 (10.6%) were AA. At time of metastatic diagnosis, AA men were younger (69 vs. 75, p < 0.001) and more likely to have PSA value greater than 50 (57.9% vs. 42.6%, p < 0.001) compared to white men. Median follow up was 15 months. There were no significant racial differences in 1L utilization, TTNT, or all-cause mortality associated with abiraterone, enzalutamide, or docetaxel use (Table). Conclusions: In this large real-world analysis of men with mCRPC who received 1L therapy, we found no significant treatment-specific differences in utilization, TTNT, or all-cause mortality between AA and white men. Long-term prospective evidence is needed to justify differential treatment selection for AA men with mCRPC.

1L utilizationTTNTOverall mortality
adjusted odds ratio
(95% CI) white vs. AA
adjusted hazard ratio
(95% CI) white vs. AA
adjusted hazard ratio
(95% CI) white vs. AA
Abiraterone
(N = 1729)
1.36
(0.96-1.91)
1.00
(0.84-1.18)
1.31
(0.93-1.84)
Enzalutamide
(N = 1255)
0.87
(0.43-1.78)
1.07
(0.91-1.26)
1.30
(0.93-1.83)
Docetaxel
(N = 549)
1.29
(0.76-2.18)
1.12
(0.85-1.47)
1.08
(0.68-1.73)

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Abstract Details

Meeting

2020 ASCO Virtual Scientific Program

Session Type

Publication Only

Session Title

Publication Only: Genitourinary Cancer—Prostate, Testicular, and Penile

Track

Genitourinary Cancer—Prostate, Testicular, and Penile

Sub Track

Prostate Cancer - Advanced Disease

Citation

J Clin Oncol 38: 2020 (suppl; abstr e17541)

DOI

10.1200/JCO.2020.38.15_suppl.e17541

Abstract #

e17541

Abstract Disclosures