Dr. Siddiqui on Defining Characteristics of Nonmetastatic CRPC

Bilal A. Siddiqui, MD, assistant professor, Genitourinary Medical Oncology, The University of Texas MD Anderson Cancer Center, discusses the nuances of defining the characteristics of nonmetastatic castration-resistant prostate cancer (CRPC).

One nuance is the castrate level of testosterone, which has a widely accepted definition of having a serum testosterone of less than 50 ng/dL, according to Siddiqui. In addition, the rise of prostate-specific antigen (PSA), despite castrate testosterone, has some differences in definition, Siddiqui adds. However, the most common use of PSA rise is defined by the Prostate Cancer Working Group 3 as a confirmed 25% increase from a nadir of 1, Siddiqui says.

Moreover, these patients have no evidence of distant metastatic disease beyond the regional lymph nodes by conventional imaging per computed tomography scans, magnetic resonance imaging, and technetium bone scan, Siddiqui explains. These nuances are important for imaging and treatment, and they will continue to change over time with the emergence of novel imaging technologies, Siddiqui adds. These are the key definitions to keep in mind for the time being, Siddiqui concludes.