Obesity and oncological outcome after radical prostatectomy: impact of prostate-specific antigen-based prostate cancer screening: results from the Shared Equal Access Regional Cancer Hospital and Duke Prostate Center Databases

Authors

  • Stephen J. Freedland,

    Corresponding author
    1. Urology Section, Department of Surgery, Veterans Affairs Medical Center,
    2. Division of Urologic Surgery and the Duke Prostate Center, Department of Surgery and
    3. Department of Pathology, Duke University Medical Center, Durham, NC,
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  • Leon Sun,

    1. Division of Urologic Surgery and the Duke Prostate Center, Department of Surgery and
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  • Christopher J. Kane,

    1. Division of Urology, Department of Surgery, University of California at San Diego Medical Center, San Diego,
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  • Joseph C. Presti Jr,

    1. Department of Urology, Stanford University Medical Center,
    2. Urology Section, Department of Surgery, Veterans Affairs Medical Center, Palo Alto,
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  • Martha K. Terris,

    1. Urology Section, Division of Surgery, Veterans Affairs Medical Center,
    2. Section of Urology, Department of Surgery, The Medical College of Georgia, Augusta, GA, and
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  • Christopher L. Amling,

    1. Division of Urology, Department of Surgery, University of Alabama at Birmingham, Birmingham, AL, USA
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  • Judd W. Moul,

    1. Division of Urologic Surgery and the Duke Prostate Center, Department of Surgery and
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  • William J. Aronson

    1. Urology Section, Department of Surgery, Veterans Affairs Medical Center, West Los Angeles,
    2. Department of Urology, University of California at Los Angeles Medical Center, Los Angeles, CA,
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Stephen J. Freedland, Division of Urologic Surgery and the Duke Prostate Center, and Departments of Surgery and Pathology, Box 2626, Duke University Medical Center, Durham, NC 27710, USA. e-mail: steve.freedland@duke.edu

Abstract

OBJECTIVE

To indirectly test the hypothesis that prostate-specific antigen (PSA)-based screening is biased against obese men due to haemodilution of PSA, and thus results in delayed diagnosis and poorer outcome beyond the biological link between obesity and aggressive prostate cancer.

PATIENTS AND METHODS

We sought to examine the association between body mass index (BMI) and the outcome of radical prostatectomy (RP) separately for men with PSA-detected cancers (cT1c) or with abnormal digital rectal examination (DRE) findings (cT2/T3), and stratified by year of treatment, using two large databases. We conducted a retrospective cohort study of 1375 and 2014 men treated by RP between 1988 and 2007 using the Shared Equal Access Regional Cancer Hospital (SEARCH) and Duke Prostate Center (DPC) databases. We evaluated the association between BMI and adverse pathological features and biochemical progression, using logistic regression and Cox proportional hazards models, adjusting for several clinical characteristics, respectively. Data were examined as a whole and as stratified by clinical stage (cT1c vs cT2/T3) and year of surgery (≥2000 vs <2000).

RESULTS

In both cohorts a higher BMI was associated with high-grade disease (P ≤ 0.02) and positive surgical margins (P < 0.001) and these results did not vary by clinical stage. A higher BMI was significantly associated with biochemical progression (P ≤ 0.03) in both cohorts. When stratified by clinical stage, obesity was significantly related to progression in both cohorts among men with T1c cancers (P ≤ 0.004) but not in men with cT2/T3 cancers (P > 0.3). Among men with T1c disease, the association between BMI and biochemical progression was limited to men treated in 2000 or later (P ≤ 0.002) and was not apparent in men treated before 2000 (P > 0.4).

CONCLUSIONS

Obese men with PSA-detected cancers and treated with RP since 2000 were at significantly greater risk of biochemical progression, while obese men treated before 2000 or diagnosed with an abnormal DRE were not at significantly greater risk of progression. These findings support the hypothesis that current PSA-based screening is less effective at finding cancers in obese men, leading to more aggressive tumours at diagnosis. Lowering the PSA threshold for biopsy among obese men might help to improve outcomes among this high-risk group.

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