Disparities in Prostate Cancer Specific Mortality Between Black and White Men According with The Type of Definitive Treatment
Nicola Frego, MD, Muhieddine Labban, MD, Mara Koelker, MD, Khalid Alkhatib, MD, Stuart R. Lipsitz, ScD, Quoc-Dien Trinh, MD, Alexander P. Cole, MD.
Brigham and Women's hospital, Boston, MA, USA.
Introduction:One factor implicated in racial/ethnic differences in prostate cancer survival is the disparity in access to high quality cancer care. There are evidence for both different patterns of treatment between racial and ethnic groups and also differences in quality within treatment types (less access to high volume surgeons among Black men receiving prostate cancer surgery, but also a tendency for Black men to choose radiation over surgery). Whether differences in prostate cancer specific mortality are predominantly within or between treatment types is not known. We therefore designed a study to assess the effect of race on prostate cancer specific survival according to the type of treatment. Material and Methods:Data on non-Hispanic Black and non-Hispanic White men diagnosed with localized intermediate- and high-risk prostate cancer in the Surveillance, Epidemiology and End Results (SEER) dataset from 2004 and 2015 was abstracted. Patients were followed up to December 2018. Multivariable logistic regression analysis was used to test the association between race and treatment type according to prostate cancer risk group. Univariable and multivariable time-to-event analyses, with the interaction term between race and treatment, were performed to assess whether the effect of race differed in different treatments for prostate cancer. Results:Overall, 71,716 (79.7%) White men and 18,294 (20,3%) Black men were included in the study (Table 1). Black men were less likely to be treated with radical prostatectomy (OR:0.46, CI:0.44 - 0.48, p<0.001), and more likely to be managed with radiotherapy (OR:1.99, CI:1.91 - 2.09, p<0.001). Regarding race-based differences in treatment, the greatest disparity in treatment choice was observed among high-risk patientswhere white men were 18.8%% less likely to receive surgery. Although Black men had worse unadjusted
cancer-specific survival (p=0.037), this difference disappeared after adjusting for treatment (aHR:1.07, CI:0.96 1.19, p=0.21) (Table 2) and the interaction between race and treatment was not significantly associated with prostate cancer specific survival (pint=0.594), suggesting there was no race-based differences in the different treatments. Within each treatment group there was no significant survival difference between Black and White men treated with radical prostatectomy (aHR for RP:1.01, CI:0.78 - 1.32, p=0.913) and with radiotherapy (aHR for RT:1.07, CI:0.94 - 1.21, p=0.268). A significantly higher mortality was found for radiotherapy compared to surgery (aHR:1.67, CI:1.51 - 1.85, p<0.001). Conclusion:While these results come with the intrinsic limitations of retrospective research, our findings support the conclusion that white and Black men treated with the same modality can achieve similar prostate cancer outcomes. Differences in treatment (rather than differences in quality of care within treatment categories) may be more important for race-based differences in prostate cancer survival.
Table 1. Clinical and demographics characteristics
| White Men71,716 (79.7%) | Black Men18,294(20.32%) | p-value | |
| Age (years) | 65 (60-69) | 62 (57-67) | <0.001 |
| cTstage | <0.001 | ||
| cT1c | 47,941 (66.85%) | 14,192 (77.58%) | |
| cT2 | 20,648 (28.79%) | 3,504 (19.15%) | |
| cT3 | 2,956 (4.12%) | 545 (2.98 %) | |
| cT4 | 171 (0.24%) | 53 (0.29%) | |
| PSA (ng/dL) | <0.001 | ||
| <10 | 50,128 (54.89%) | 10,924 (38.19%) | |
| 10-20 | 13,360 (17.7%) | 4,181 (16.7%) | |
| >20 | 5,308 (27.41%) | 2,451 (44.82%) | |
| Biopsy Gleason Score (GS) | 0.001 | ||
| GS6 | 1,128 (11.32%) | 2,019 (11.04%) | |
| GS7 | 3,365 (66.99%) | 12,389 (67.72%) | |
| GS8 | 9,788 (13.65%) | 2,572 (14.06%) | |
| GS9 | 5,344 (7.45%) | 1,232 (6.73%) | |
| GS10 | 426 (0.59%) | 82 (0.45%) | |
| Positive Biopsy Cores, n 1-34-67-9>10 | 19,791 (38.11%)18,433 (35.49%)8,358 (16.09%)5,354 (10.31%) | 4,680 (34.97%)4,512 (33.72%)2,430 (18.16%)1,760 (13.15%) | <0.001 |
| Prostate cancer Risk Group | <0.001 | ||
| Intermediate-Risk | 61,092 (85.19%) | 15,381 (84.08%) | |
| High-Risk | 10,624 (14.81%) | 2,913 (15.92%) | |
| Treatment | <0.001 | ||
| Radical Prostatectomy | 41,013 (57.19%) | 8,016 (43.82%) | |
| Radiotherapy | 30,703 (42.81%) | 10,278 (56.18%) | |
| Follow-up, (months) | 71 (50-91) | 68 (48-89) | <0.001 |
Table 2. Multivariable Cox proportional hazard models for the prediction of prostate cancer specific mortality
| Variables | OR (95% CI) | p-value |
| Race | ||
| Non-Hispanic White men | Ref | - |
| Non-Hispanic Black men | 1.07 (0.96 1.19) | 0.21 |
| Treatment | ||
| Radical prostatectomy | Ref. | - |
| Radiotherapy | 1.68 (1.53 1.86) | <0.001 |
| Age | 1.02 (1.01 1.05) | <0.001 |
| Clinical T stage | ||
| cT1c | Ref. | - |
| cT2a | 1.18 (0.99 1.39) | 0.05 |
| cT2b | 1.36 (1.17 1.57) | < 0.001 |
| cT2c | 1.48 (1.29 1.70) | < 0.001 |
| cT3 | 1.94 (1.68 2.25) | < 0.001 |
| cT4 | 5.21 (3.95 6.87) | < 0.001 |
| PSA level (ng/dl) | ||
| PSA < 10 | Ref. | - |
| PSA 10-20 | 1.53 (1.38 1.71) | < 0.001 |
| PSA > 20 | 1.95 (1.73 2.19) | < 0.001 |
| Biopsy Gleason Score | ||
| Biopsy GS 6 | Ref. | - |
| Biopsy GS 7 | 1.18 (1 1.38) | < 0.001 |
| Biopsy GS 8 | 4.64 (3.74 5.76) | < 0.001 |
| Biopsy GS 9 | 9.41 (7.59 11.65) | < 0.001 |
| Biopsy GS 10 | 17.37 (13.02 23.16) | < 0.001 |
| Number of positive cores | ||
| 1-3 | Ref. | - |
| 4-6 | 1.18 (1 1.38) | 0.048 |
| 7-9 | 1.69 (1.42 2.01) | < 0.001 |
| 10-24 | 2.19 (1.83 2.62) | < 0.001 |
| Year of diagnosis: | ||
| 2004 2007 | Ref. | - |
| 2008 2011 | 0.53 (0.43 0.66) | < 0.001 |
| 2012 2015 | 0.50 (0.39 0.62) | < 0.001 |
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