There are several risk assessment tools and clinical practice guidelines used in the management of localized prostate cancer (PCa). These include the D’Amico classification, the Cancer of the Prostate Risk Assessment (CAPRA) score, the National Comprehensive Cancer Network (NCCN) risk criteria, and the American Urological Association (AUA) clinical practice guidelines.1-4 None of these tools incorporate the BRCA1 and BRCA2 genes in the risk assessment or treatment recommendations for localized PCa.5 The BRCA mutations are most strongly associated with breast and ovarian cancer risk. However, BRCA mutations also increase susceptibility and disease progression in PCa.6 This article illustrates the current knowledge gap in PCa treatment algorithms for the BRCA2-positive patient population.
Traditional risk assessment tools use clinical and pathologic features of PCa, including prostate-specific antigen (PSA) level, Gleason score, tumor stage, and disease burden to measure cancer aggressiveness.1,7,8 These criteria are the basis of the AUA and NCCN guidelines for management of clinically localized PCa, which recognize 3 categories of clinically localized disease (low, intermediate, and high risk).3,4 The NCCN guidelines (version 1.2016) include a fourth category (very low risk or pathologically insignificant PCa) among some stage T1c patients, based on additional criteria, including PSA density. Both the AUA and NCCN recommend active surveillance as a treatment option for men with low-risk PCa. The NCCN recently revised its guidelines to state that intermediate-risk patients with PCa with favorable features (Gleason grade 3 and < 50% of positive biopsy cores) may also be considered for active surveillance.3
BRCA Mutations in Prostate Cancer
Estimates of the relative risk of PCa for men with BRCA1 and BRCA2 mutations have varied, but recent data suggest that it is 3.75-fold for BRCA1 mutations and 8.6-fold for BRCA2 by age 65 years.9-11 Moreover, PCas associated with BRCA1/2 mutations, particularly those in the BRCA2 gene, are often more aggressive and characterized by poor outcomes.12,13 The presence of a BRCA2 mutation is a negative prognostic factor in PCa, independent of tumor grade, stage, and PSA levels.14 Both PCa-specific survival and metastasis-free survival rates following surgical or radiation therapy are significantly lower in the BRCA mutation carriers than in noncarriers.15 Preliminary results of the IMPACT study demonstrate that targeted PCa screening in men with BRCA1 or BRCA2 mutations may result in identification of tumors more likely to require treatment.16
As a result of these increased risks, it is recommended that men with BRCA2 mutations begin PCa screening at age 40 years; however, there are no clear guidelines for clinical management of PCa in this group of patients.5 The lack of guidelines presents a challenge for clinical management of BRCA1/2 mutation carriers with localized PCa who otherwise qualify for active surveillance. A recent editorial by Bratt and Loman specifically
calls for aggressive therapy for patients who are BRCA positive, particularly BRCA2 carriers, suggesting the need to combine early radical local treatment with adjuvant systemic therapy.17 However, data on the effectiveness of aggressive therapies in patients with PCa who carry BRCA2 mutations are sparse.5
Genomic Test for Risk
There is growing recognition of the need to include molecular testing to improve risk assessment in PCa. Using traditional risk assessment tools, about 8% of low-risk patients are found to have progressive disease postoperatively.3 Current AUA guidelines from 2007 are silent on the issue of molecular testing. The 2015 and 2016 NCCN guidelines include molecular testing for better risk stratification of patients with PCa, specifically naming Oncotype DX Prostate Cancer Assay (Genomic Health, Redwood City, CA) and Prolaris (Myriad Genetics, Salt Lake City, UT).3 However, they do not address molecular BRCA mutation testing.
There are several genomic tests aimed at improving PCa risk assessment. These include Oncotype DX PCa Assay; Prolaris; Decipher Prostate Cancer Classifier (GenomeDx Biosciences, San Diego, CA); and ProMark (Metamark Laboratories, Cambridge, MA). These assays are tissuebased and measure gene expression on the RNA or protein level to identify low- or intermediate-risk patients who may be candidates for active surveillance, as well as patients at higher risk who may benefit from closer monitoring or additional therapy after their initial treatment. By 2015, the Centers for Medicare and Medicaid Services had issued positive coverage decisions for several tests.18
The Oncotype DX test is a quantitative real-time polymerase chain reaction assay that measures the expression of 17 genes (12 cancer-related genes and 5 reference genes) representing 4 biologic pathways, including from the androgen signaling, stromal response, cellular organization, and cellular proliferation (Table). Prolaris focuses on a larger number of genes in the cell-cycle progression (CCP) pathway (31 cell-cycle-related genes and 15 reference genes). There is no overlap between the 2 gene sets. Both tests integrate genomic data with clinical and histopathologic characteristics of the tumor to arrive at prognostic information. The Oncotype DX test yields a specific Genomic Prostate Score (GPS; scaled 0-100) that is integrated with the patient’s NCCN clinical risk group to quantify the likelihood of favorable pathology, which is defined as low-grade organ-confined disease.19 The Prolaris test uses the patient’s AUA risk category and then evaluates the patient’s risk based on the cell-cycle progression
gene panel compared with that risk category. It also provides an estimate of disease-specific mortality as validated by 2 independent cohorts that were managed conservatively initially with watchful waiting.
In this article, the authors present a case report of a BRCA2-positive veteran with newly diagnosed lowrisk PCa and a history of breast cancer. In addition to evaluating clinical criteria, Oncotype DX and Prolaris gene expression tests were ordered for this patient. The authors obtained veteran and institutional review board permission. To protect the identity of the patient, minor changes were made to patient demographics.
Case Presentation
A 68-year-old white man with a history of coronary artery disease, dyslipidemia, and hypertension, was recently diagnosed with PCa. He presented to Genomic Medicine Service to discuss how his BRCA2 mutation status might impact management decisions for PCa. Priorto the PCa diagnosis, the veteran had a history of breast and skin cancer. He was diagnosed with invasive ductal carcinoma of the right breast (ER+/PR+/Her2+) at age 62 years and treated with mastectomy and tamoxifen. He had testing at that time, which revealed a BRCA2 mutation: 3773delTT. Squamous cell carcinoma was detected on his right leg and removed at age 64 years. Basal cell carcinoma was removed from his left forehead first at age 65 years, and then residual basal cell carcinoma was removed from the forehead 2 months later.