Precision medicine is changing landscapes in healthcare. One area of great interest is figuring out better ways to stratify patients into appropriate therapeutic and prognostic categories for their particular cancer. In the March 2018 publication of the Journal of Clinical Oncology, researchers outlined the results of a new risk group classification, both developed and validated, combining clinical and genomic testing of biopsied localized prostate cancer tissue. Prostate cancer can be aggressive or indolent; the current guides make it challenging to determine which men to monitor long term and which are at more immediate risk of death from their cancer.
The currently accepted prostate cancer treatment guidelines from the National Comprehensive Cancer Network (NCCN) include prostate-specific antigen (PSA) level, cancer grade and tumor staging as the criteria for assigning cancer patients into risk groups. These groups have different therapeutic and prognostic implications for patients. According to the first author of the study, Dr. Daniel Spratt included that the NCCN model is not necessarily designed to identify and predict which men will develop metastases or die of their cancer.
The researchers utilized genetic testing results evaluating the presence of 22 genes known to increase the risk of metastatic disease. The combination of genes present provided the group an opportunity to evaluate the gene expression for nearly 7,000 men from multiple clinical sites. Through the analysis of expression patterns, the study authors developed two new clinical-genomic system models for assigning risk to the patients. One system had three tiers and one system had 6 tiers. The authors evaluated the men on all three risk grouping models (NCCN, three tiered, and six-tiered) and then compared those results to patient outcomes and development of metastatic disease. The new risk models were found, however, to be challenging to blend with the traditional NCCN guidelines so the authors have suggested combining them to create a new genomic-clinical system that standardizes the use of the biomarkers.
The results? There were differences between the models indicating that both proposed tiered systems more accurately predicted/identified men whose disease remained slow growing and those that had more aggressive forms of prostate cancer that progressed and metastasized. Using the six-tiered system, 67% of men would have been reclassified to the lower-risk slow-growing cancer group, meaning deferred treatment and careful monitoring of the condition. The benefits include lowering costs, both for the patient (time, side effects, etc.) and for healthcare (fiscal, resources, etc.).
The new model also identifies a pool of high-risk men whose disease, if only monitored, were likely to die of prostate cancer. Providers who use these models can more accurately propose near term treatments like radiation or clinical trials and a prognosis that better match the likely progression of their disease.
There are clear benefits to the new models including increased efficiently and precision in providing prognoses and therapy recommendations for patients; there are also increased costs up front for the healthcare system/patient for the gene expression testing for all newly diagnosed men. There is also the challenge of creating a consensus on a new usable genetic-clinical risk system; molecular profiling is not a magic bullet and clinical evaluation must be included (PSA and Gleason score).