Among the estimated 230,000 men diagnosed with prostate cancer in the US each year there has been a rise in the number of radical prostatectomies (RP). There is some debate over the value of immediate adjuvant therapy following RP in men with high-risk pathological features versus delayed salvage radiation therapy when signs of disease progression are observed. Thus, it would be potentially useful to inform post-RP management strategies by more clearly identifying those patients at higher risk of progression and death from prostate cancer. A 22 gene-expression assay, Decipher® (GenomeDx Biosciences), has been developed in men treated with radical prostatectomy to predict the five-year risk of metastatic prostate cancer. Published and unpublished literature was evaluated to determine the analytic validity, clinical validity and clinical utility of Decipher. Limited information is available on the analytic validity of Decipher. In both discovery and validation studies, Decipher was shown to have good performance in discriminating men with metastasis from men without metastasis five years after surgery (AUC 0.75 to 0.90). In terms of clinical utility, no evidence was found reporting improved outcomes (lower prostate cancer specific mortality and treatment related adverse effects) from using this test to guide post-operative treatment. Four studies provided weak indirect evidence of clinical utility in which 31% to 43% of post-operative treatment recommendations were changed in men with high-risk prostate cancer based on test results, with 27% to 52% of treatment recommendations changing from any treatment to no treatment.
In contemporary oncology practices there is an increasing emphasis on concurrent evaluation of multiple genomic alterations within the biological pathways driving tumorigenesis. At the foundation of this paradigm shift are several commercially available tumor panels using next-generation sequencing to develop a more complete molecular blueprint of the tumor. Ideally, these would be used to identify clinically actionable variants that can be matched with available molecularly targeted therapy, regardless of the tumor site or histology. Currently, there is little information available on the post-analytic processes unique to next-generation sequencing platforms used by the companies offering these tests. Additionally, evidence of clinical validity showing an association between the genetic markers curated in these tests with treatment response to approved molecularly targeted therapies is lacking across all solid-tumor types. To date, there is no published data of improved outcomes when using the commercially available tests to guide treatment decisions. The uniqueness of these tests from other genomic applications used to guide clinical treatment decisions lie in the sequencing platforms used to generate large amounts of genomic data, which have their own related issues regarding analytic and clinical validity, necessary precursors to the evaluation of clinical utility. The generation and interpretation of these data will require new evidentiary standards for establishing not only clinical utility, but also analytical and clinical validity for this emerging paradigm in oncology practice.
Women with early stage breast cancer frequently receive adjuvant chemotherapy to prevent recurrence; however, not all patients benefit. Recently, gene expression marker panels, such as Oncotype DX, that may better predict risk of breast cancer recurrence have become commercially available and are being used to guide treatment decisions. Oncotype DX analyzes the expression of 21 genes within a tumor to determine a recurrence score that corresponds to a specific likelihood of breast cancer recurrence within 10 years of the initial diagnosis, as well as response to adjuvant treatment. We examined the published literature on the analytic validity, clinical validity, and clinical utility of Oncotype DX in guiding adjuvant treatment decisions in women with lymph node-positive breast cancer.
Lung cancer is the second most common cancer and the leading cause of cancer-related deaths in the United States. Moreover, advanced non-small-cell lung cancer (NSCLC) is considered an incurable disease and current treatment approaches provide marginal improvement in overall survival at the expense of substantial morbidity and mortality, highlighting the need for new, less toxic treatment approaches. Tyrosine kinase inhibitors, such as erlotinib (Tarceva®), have been developed and approved as maintenance, second- and third-line treatment options in unselected advanced NSCLC patients (2, 15). However, subgroup analyses from the initial clinical trials consistently showed that patients with epidermal growth factor receptor (EGFR) mutations who received erlotinib had higher rates of response and better progression-free and overall survival, leading to clinical trials specifically focused on the use of tyrosine kinase inhibitors as first-line therapy in these patients. We examined the published literature on the analytic validity, clinical validity, and clinical utility of EGFR mutational testing in guiding first-line therapy use of erlotinib to treat advanced NSCLC and we briefly summarized the current lung cancer screening guidelines. The primary goal was to provide a basic overview of EGFR mutational testing and use of erlotinib as first-line therapy and identify gaps in knowledge and evidence that affect the recommendation and adoption of the test in advanced NSCLC treatment management strategies.