Abstract A005: Patterns in distant metastasis at diagnosis in a racially diverse, longitudinal cohort of prostate cancer patients: 1989-2013
Authors: McCauley John , Kuo Huai-Ching , Rosner Inger L. , Chen Yongmei , Hurwitz Lauren , Stroup Sean , Sterbis Joseph R. , Porter Christopher , Brand Timothy C. , Srivastava Shiv , Cullen Jennifer 
Published: February 2019

Introduction: The introduction of PSA screening in the U.S. and its nationwide use as a prostate cancer (PCa) screening modality led to a spike in the incidence of localized PCa in the early 1990s. With this shift toward earlier stage disease at presentation, concerns were raised for overdetection and overtreatment of clinically insignificant PCa. In response to such concerns, professional guidelines on PSA screening practices have changed over time. In 2008 the US Preventive Services Task Force (USPSTF) gave PSA screening for detection of prostate cancer a Grade D recommendation for older men (&gt;=75 years), and in 2012 this grade D was extended to men of all age. More recently, in 2017 a draft of revised guidelines was released, elevating the letter Grade to C, only for men aged 55-69 years. Yet three compelling studies have been published that reveal increases in the diagnosis of metastatic PCa (mPCa) in U.S. men, with provocative associations in time to changes in PSA screening guidelines, prompting concern that a stage shift toward more advanced PCa at diagnosis may be occurring.

The primary aim of this study was to examine time trends in mPCa at time of diagnosis, over a 20+-year study period, in a racially diverse longitudinal cohort with equal access to health care. The primary hypotheses were that mPCa at diagnosis declined after the introduction of PSA screening and that such declines would be comparable in both Caucasian (CA) and African American (AA) patients in this cohort.

Methodology: The Center for Prostate Disease Research (CPDR) Multi-Center National Database was the source of patients for this study. Men under suspicion for PCa and undergoing TRUS-guided biopsy for PCa detection are eligible for enrolment in this database. This study focused on those with biopsy-confirmed PCa between January 1, 1989 and December 31, 2013. Trends in mPCa at the time of diagnosis were examined for the overall cohort, as well as stratified by race (AA and CA) and patient age at CaP diagnosis (&lt;75 years versus ≥75 years). Poisson regression with a log link function was used to estimate annual percent change (APC) in mPCa at diagnosis, as a proportion of all newly diagnosed PCa per year. Multivariable logistic regression was used to model predictors of mPCa at diagnosis as a function of PSA screening history and race.

Results: A total of 462 men presented with mPCa and were eligible for inclusion. The decline in APC for the overall cohort was statistically significant (APC = -8.5%, p &lt;0.0001). When APCs were computed for across race, both AA and CA patients were observed to have statistically significant negative change over time in APC (-10.1%, p&lt;0.0001 and -8.7%, p &lt;0.0001, respectively). However, there was no interaction between race and year of metastatic PCa diagnosis (p=0.49). When stratified by age group, patients aged ≥75 years had a smaller magnitude of decline in APC compared to those &lt;75 years (-3.9%, p&lt;0.0001 and -10.1%, p&lt;0.0001, respectively). The interaction between age group and diagnosed year was significantly different (p=0.0011). In multivariable analysis, both the number of prior PSA screenings (OR ≥5 vs. None = 0.35, p &lt;0.0001 = 0.35, p &lt;0.0001) and race (OR for AA vs. CA=1.77, p&lt;0.0001) strongly predicted mPCa.

Conclusions: In this longitudinal, racially diverse cohort with equal health care access, significant declines in mPCa at diagnosis were observed over a 20+-year study period. This is contrast to other recent studies that have demonstrated increases in mPCa following changes in USPSTF guidelines. There was, however, a difference in the magnitude of decrease in oldest patients (≥75 years) compared to younger men, which may have been influenced by changing PSA screening recommendations in 2008 by the USPSTF. Continued attention to shifts in mPCa at diagnosis is needed to determine the impact of changes in screening recommendation.

Citation Format: John McCauley, Huai-Ching Kuo, Inger L. Rosner, Yongmei Chen, Lauren Hurwitz, Sean Stroup, Joseph R. Sterbis, Christopher Porter, Timothy C. Brand, Shiv Srivastava, Jennifer Cullen. Patterns in distant metastasis at diagnosis in a racially diverse, longitudinal cohort of prostate cancer patients: 1989-2013 [abstract]. In: Proceedings of the AACR Special Conference: Prostate Cancer: Advances in Basic, Translational, and Clinical Research; 2017 Dec 2-5; Orlando, Florida. Philadelphia (PA): AACR; Cancer Res 2018;78(16 Suppl):Abstract nr A005.