Testing a new risk stratification tool in African American men diagnosed with prostate cancer

Christopher Warlick, MD, PhD, Assistant Professor, University of Minnesota
Charles Rogers, PhD, CHES, Assistant Professor, University of Minnesota

Prostate cancer disproportionately affects African American men, who can be twice as likely to be diagnosed with, and die from, this disease as their Caucasian counterparts. There are many different reasons for this statistic: social and cultural issues as well as biologic differences such as the location in the prostate where cancers arise which can make diagnosis difficult in African American men and the differences in the genes affected in the cancers of African American men as opposed to Caucasians. Further, not all prostate cancer is created equally. Some prostate cancers can be life-threatening, while some are so slow-growing that physicians are able to monitor them without intervention because it is likely that the patient will die with the cancer, not because of it. However, it can be hard to determine if a prostate cancer is the type that can be monitored or if it is more aggressive.

Several new tools have recently become available to help determine if a prostate cancer is the slow-growing or the more aggressive type. These tools look at the gene expression profile on the prostate biopsy specimen taken at the time of the cancer diagnosis. Certain gene expression profiles suggest a cancer is more aggressive than what would be expected based on the other clinical features, while some profiles guest a less aggressive cancer. This additional information can be very important in deciding whether to observe a cancer, or undergo immediate treatment. This can be a difficult decision because treatment carries risks of side effects that can affect urinary, bowel, and sexual functions, which can decrease a man’s quality of life.

During the FDA clearance for these new risk stratification tools, very few African American men were tested. Therefore, it is unclear whether these tests perform the same in African American men as they do in Caucasian men, especially since there is some question whether there are biological differences in the cancers that arise in African American men as opposed to Caucasian men. Therefore, inadvertent misuse of such testing could have very serious consequences if it incorrectly characterizes a man’s cancer.

The purpose of our CHAAMPS research pilot is to do additional research on one of these prostate cancer diagnostic tools, the Oncotype Dx test, with African American men. In conjunction with our collaborators at the University of  Minnesota, University of Alabama at Birmingham, and University of California at Davis, we have gathered a series of specimens from African American men who have had prostate biopsies showing cancer and underwent prostatectomy. We are running the Oncotype Dx assay on the specimens taken at diagnosis to see if it accurately predicts the aggressiveness of the cancer as seen on the prostatectomy specimen. Results from this work will help provide insight into whether this test can be safely applied in African American men, or whether the test needs to be interpreted differently in these men. This type of work is important to make sure that African American men are able to take advantage of the revolution in personalized medicine that is taking place in medical care.

A second part of our project is to determine if there are barriers to using this genomic testing for things such as prostate cancer within the African American community, given a history of some level of distrust of the medical system. In addition, since one of the fundamental problems making our study necessary is the relative lack of participation in clinical trials by African Americans, we also sought to determine attitudes towards participation in clinical trials, and ideas for future clinical trials that the African American community might be interested in. Towards this end, we are also conducting focus groups at our participating institutions to address these questions. Results from this aspect of our study will be used to suggest solutions to any identified barriers to the use of genomic testing among African Americans, and to inform future research questions that the community has identified as important. We anxiously await the results of our study.