WHITE RIVER JUNCTION, VT — For the physicians treating men with non-metastatic castration resistant prostate cancer, knowing the risk of progression or death provides valuable information to guide the timing and selection of treatment. Because nearly all men who receive androgen deprivation therapy following a rise in prostate specific antigen (PSA) after radiation or surgery with curative intent will eventually become resistant, many patients and physicians find themselves in this no man’s land of uncertainty.
A VA study released in conjunction with the 2018 American Society of Clinical Oncology Annual Meeting being held this weekend in Chicago provides some direction.1
The study, led by researchers from the White River Junction, VT, VAMC, demonstrated that prostate specific antigen doubling time (PSADT) accurately stratifies patients with non-metastatic castration resistant prostate cancer (nmCPRC) and strongly corresponds to overall survival times. Veterans with a doubling time of less than three months had median overall survival of 21 months compared to 36 months for those with a doubling time of three to nine months. Patients with a doubling time of nine to 15 months had a median overall survival more than 2.5 times longer than those in the group with the fastest doubling time, 54 months.
The VA treats more men with prostate cancer than any other health system in the U.S. Between 2007 and 2017, 653,747 veterans receiving VA care received a diagnosis of prostate cancer. Of those, researchers included 13,552 with non-metastatic castration-resistant prostate cancer in the study. In keeping with the recommendation of the Prostate Cancer Working Group 2, they defined non-metastatic castration-resistant prostate cancer as a rise in PSA of 25% from the nadir with a minimum rise of 2 ng/mL in the presence of castrate testosterone levels of less than 50 ng/dL or while receiving continuous androgen deprivation therapy. The average age of participants was 76.4 years and two-thirds of the patients were white.
With a mean follow up of 36 months, 6,552 men died. When analyzed by doubling time, veterans with a doubling time of three to nine months had a 30% reduction in risk of death compared to those with a doubling time of three months or less. Those with a doubling time of nine to 15 months had a 42% the risk of death of those with the fastest doubling time.
The researchers also reported that the development of metastases more than tripled the risk of death and that a higher log PSA at baseline increased the risk of death 15%.
“In this study of veteran men with nmCRPC, higher baseline PSA, a shorter PSADT, and the development of metastases were associated with an increase in the risk of death,” study authors wrote.
1Fuld AD, Young-Xu Y, Li S, et al. Predictors of overall survival in veterans with non-metastatic castration resistant prostate cancer. 2018 ASCO Annual Meeting. Abstract e17057.