AUA 2018: Do Anterior Tumor Location and Race Predict Biochemical Outcomes for Low Risk Prostate Cancer Patients?

San Francisco, CA (UroToday.com) Over the past two decades, there has been increasing uptake and adherence to active surveillance protocols for patients with very-low or low risk prostate cancer [1-3]. However, the uptake and eligibility of African Americans (AA) monitored on active surveillance is less clear as studies have suggested that these patients may be at increased risk of PCa progression compared to Caucasians.

One potential reason is that AA patients may have a greater proportion of tumor involvement of the anterior region of the prostate gland (51% vs 29%, p=0.003) compared to Caucasians, which may be associated with higher grade disease and larger tumor volume [4]. As such, Justin Mygatt, MD, and colleagues from the Walter Reed National Military Medical Center discussed in their experience whether anterior tumors and/or race predict biochemical outcomes for low risk prostate cancer patients that elected for a radical prostatectomy. 

For this retrospective institutional cohort study, patients were enrolled who had biopsy-confirmed, NCCN-defined low risk prostate cancer (T1-T2, Gleason score ≤6, PSA <10 ng/mL) who underwent radical prostatectomy between 1993-2008. Tumor location was recorded for index tumors (i.e, largest/highest grade) in whole-mounted radical prostatectomy specimen sections. Additional outcomes included presence of ERG protein expression in the predominant tumor. Student t test and Wilcoxon rank sum test or Chi square test were used to evaluate the difference between tumor location and pathologic outcomes, stratified by race. Kaplan Meier estimation curves were used to model BCR-free survival as a function of patient race and tumor location. 

Mygatt and colleagues identified 597 patients (148 AAs and 449 Caucasians) who met study eligibility criteria. The predominant tumor was located in the anterior prostate in 111 cases (18.6%). Anteriorly located tumors compared to other tumors were noted to have a lower prevalence of ERG protein expression compared to tumors arising from other areas of the prostate (16.7% versus 59.4%, p<0.0001). Interestingly, and contrary to previously published studies [3], there was no difference in the prevalence of anterior tumor observed across race (16.9% AA versus 19.2% Caucasian, p=0.54). Patients with anterior tumors had significantly lower pathological grade, less extra-capsular extension, less seminal vesicle involvement, and lower nuclear grade compared to other predominant tumor location. Predominant tumor location and race were not predictors of BCR-free survival independently or jointly.

RaceTumorLocation AUA2018
The strength of this study is the heterogeneous and racially diverse cohort of patients with a relatively decent ratio of AA to Caucasian patients unique to the military setting of this study. A possible limitation is the relatively low number of anterior prostate lesions. With the contrary findings of this study compared to what has previously been published, further work is needed to continue to delineate the impact (or lack thereof) of anterior located predominant prostate cancer lesions. Mygatt provided several important take-home points for this study:

  • Among patients with low-risk disease undergoing radical prostatectomy, there was no difference in the frequency of anterior tumor involvement between AA and Caucasian men
  • Tumors arising in non-anterior locations had a higher pathological grade, greater ECE and SVI, and worse nuclear grade 
  • No racial disparity in outcome was observed, suggesting that active surveillance is a reasonable option for AA men with low risk prostate cancer 
  • Larger, prospective active surveillance studies with long-term follow up for AA men are needed.
References:
1. Klotz L, Vesprini D, Sethukavalan P, et al. Long-term follow-up of a large active surveillance cohort of patients with prostate cancer. J Clin Oncol 2015;33(3):272-277.
2. Richard PO, Alibhai SM, Panzarella T, et al. The uptake of active surveillance for the management of prostate cancer: A population-based analysis. Can Urol Assoc J 2016;10(9-10):333-338.
3. Loeb S, Byrne N, Makarov DV, et al. Use of conservative management for low-risk prostate cancer in the Veterans Affairs Integrated Health Care System from 2005-2015. JAMA 15 May 2018 [Epub ahead of print].
4. Sundi D, Kryvenko ON, Carter HB, et al. Pathological examination of radical prostatectomy specimens in men with very low risk disease at biopsy reveals distinct zonal distribution of cancer in black American men. J Urol 2014;191(1):60-67.


Presented by: Justin Mygatt, MD, Ph.D. Walter Reed National Military Medical Center, Medical Center, Bethesda, MD
Co-Authors: Jennifer Cullen, Huai-ching Kuo, Yongmei Chen, Rockville, MD, Allen Burke, Silver Spring, MD, Shiv Srivastava, Rockville, MD, Kevin Rice, Inger Rosner, Bethesda, MD, Isabell Sesterhenn, Silver Spring, MD

Written by: Zachary Klaassen, MD, Urologic Oncology Fellow, University of Toronto, Princess Margaret Cancer Centre at the 2018 AUA Annual Meeting - May 18 - 21, 2018 – San Francisco, CA USA
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