This month we will be focusing on data from the recent 2009 Genitourinary Cancers Symposium. This meeting was held on February 26-28, 2009 in Orlando, FL and co-sponsored by the American Society of Clinical Oncology (ASCO), the American Society for Therapeutic Radiology and Oncology (ASTRO), and the Society of Urologic Oncology (SUO). The following topics were presented as part of educational sessions along with oral abstract presentations.

Prostate Cancer

Prostate cancer accounted for the majority of abstracts submitted to the 2009 Genitourinary Cancers Symposium.

Prevention

The Selenium and Vitamin E Cancer Prevention Trial (SELECT) prevention trial was presented as the initial abstract of the meeting.⁹ In this study, 32,400 men were to be randomized to 1 of 4 arms: selenium, vitamin E, the combination of the 2, or placebo for a planned minimum of 7 years and a maximum of 12 years. Between 2001 and 2004, 35,533 men were randomly assigned to 1 of the arms. All 4 arms were well balanced with regards to potentially important risk factors for developing prostate cancer. The study supplements were discontinued at the 7-year interim analysis because the evidence convincingly showed no benefit from either study agent. Interestingly, there were nonsignificantly increase risks of prostate cancer in the vitamin E arm and of type 2 diabetes mellitus in the selenium arm, but they were not observed in the combination arm. The conclusion is that selenium or vitamin E alone, or in combination did not prevent prostate cancer in this population of men aged >50 for African American men and aged >55 for all others.

Screening and Risk Assessment

Roobol, et al from Rotterdam, Netherlands presented results of data from the Rotterdam section of the European randomized study of screening for prostate cancer.¹⁰ Using multivariate logistic regression analysis, they sought to assess the predictive value of prostate-specific antigen (PSA) level, digital rectal examination (DRE) and transrectal ultrasound (TRUS) outcome, prostate volume, a previous negative biopsy, family history of prostate cancer, and age at the time of a second round of screening 4 years from the first in 5176 men. Although PSA still turned out to be the most significant predictor, other factors including family history, and prostate volume, and a negative prior biopsy significantly influenced risk. The authors used a plot of these data to predict for a 5% and 10% future risk for prostate cancer. It was suggested that these factors could give an individual person their risk and may affect behavior with regards to heightened surveillance or active risk reduction with medications such as finasteride. This study is currently in press with the Journal of Urology.

Diagnostics

It has been previously described that there exists a fusion between 2 genes in about half of prostate cancers, and has been associated with adverse clinical outcomes. The fusion occurs between TMPRSS2 (T2), which is an androgen-responsive gene, and the oncogenic transcription factor ERG. The fusion is referred to as the T2:ERG gene fusion. Dr J Groskopf and colleagues presented interim results from a collaborative study designed to verify the clinical utility of a T2:ERG urine test.¹¹ Urine specimens were prospectively collected following DRE from men scheduled for a prostate biopsy. Urine results were correlated with biopsy outcome. Biopsy tissue T2:ERG mRNA results were also obtained. The test has been used on urine specimens collected in 556 men and predicted the presence of prostate cancer with a specificity of 84% compared to a specificity of PSA of 27%. There was also noted to be correlations between a positive test and indicators of cancer aggressiveness, the Gleason score, and the percent of prostate cancer involvement suggesting a correlation of T2:ERG status and a more aggressive phenotype of prostate cancer.

Therapeutics

Multiple trials were presented using systemic therapy for patients with castration-resistant metastatic prostate cancer (CRPC). At this point, there is only 1 US Food and Drug Administration (FDA)–approved agent to treat CRPC that is docetaxel. Clinicians continue to look toward the myriad of clinical trials being undertaken for this group of advanced prostate cancer patients. The most compelling of these trials presented included abiraterone acetate, a steroidal inhibitor of CYP-17, blocking 2 enzymatic activities in the synthesis of testosterone; MDV3100, a novel small molecule androgen receptor (AR) antagonist; and dasatinib, a potent oral SRC family kinase inhibitor which appears to have both anti-tumor and anti-osteoclast activity. These agents, in addition to many others are still being investigated in the phase II setting and there are future plans for phase III trials.^12-14

OncoFacts™ Editor:

Christy Russell, MD

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