According to a study last year at Fox Chase Cancer Center, men whose prostate specific antigen (PSA) rise within 18 months of having primary radiotherapy are more likely to develop advanced prostate cancer and die of their disease.
The study was presented by oncologist Mark K. Buyyounouski, M.D., M.S. at last year’s annual meeting of the American Society for Radiation Oncology (ASTRO).
Dr. Buyyounouski said, “PSA is the gold standard for following prostate cancer patients after they receive radiation or surgery. But we don’t know if having PSA rise sooner means a patient has a greater danger of dying of prostate cancer, though it seems logical.”
Buyyounouski and his colleagues showed previously that men who suffered an early biochemical failure, which is defined as their lowest PSA level (nadir) plus 2 ng/mL, were at greater risk of dying of prostate cancer. This study confirms these conclusions.
This study has immediate potential clinical value to any of us who has had primary radiotherapy. “Now we can use the simple criteria from this study, which is widely available for anyone who has PSA testing, to identify men who have a greater than 25% chance of dying from prostate cancer in the next five years. That is huge. There is nothing else that can do that,” says Buyyounouski.
The analysis of data for this study included a total of 2,132 men with localized prostate cancer who suffered biochemical failure after treatment. The median interval between treatment and biochemical failure was 35.2 months for the entire study group. However, 19% of men developed biochemical failure at 18 months or less. The five-year cancer-specific survival for these men was 69.5% compared with 89.8% for men who developed biochemical failure after 18 months.
A multivariate analysis showed that the interval to biochemical failure correlated with cancer specific survival, as did Gleason score, tumor stage, age, and PSA doubling time. However, the interval to biochemical failure had the best predictive value for cancer-specific mortality, compared with the other variables.
Given the high rates of side effects, including the potential for fatal side effects many physicians prefer to be more conservative and not start hormone treatment based on biochemical failure alone, but rather wait until the PSA reaches a high level or there is some other evidence tumor spread. “The potential impact of this finding is that patients can initiate treatment far sooner without waiting for other signs or symptoms of prostate cancer,” Buyyounouski says. “If a patient has biochemical failure at 16 months, rather than wait and learn later that the PSA is rising sharply and risk the development of distant metastasis, therapy can be started sooner based on the increased risk of death.”
On the flip side, men with a biochemical failure longer than 16 months from primary treatment can consider delaying the start of hormone therapy along with its side effects.
Joel T Nowak, MA, MSW