PSA increase predicts prostate cancer outcome

The time it takes for prostate-specific antigen (PSA) levels to double can help predict the clinical outcome of patients with Prostate cancer who have been treated with combined radiation and hormone therapy, researchers report in the International Journal of Radiation Oncology, Biology, Physics.

"Since patients with PSA recurrences after treatment for Prostate cancer have significant variability in subsequent clinical outcomes, other parameters such as PSA kinetics have been used to better predict those patients who may develop symptomatic recurrences or decreased survival," said lead investigator Dr. Andrew K. Lee.

"Brief PSA doubling time," he continued, "has been shown to be significant for predicting clinically apparent recurrences."

In the current study, Lee and colleagues at the University of Texas M. D. Anderson Cancer Center, Houston reviewed data on 621 men with Prostate cancer that had not spread to other areas of the body. Overall, 62 men experienced some degree of clinical failure and 22 had true clinical failure.

The cause of prostate cancer is unknown, although some studies have shown a relationship between high dietary fat intake and increased testosterone levels. When testosterone levels are lowered either by surgical removal of the testicles (castration, orchiectomy) or by medication, prostate cancer can regress. There is no known association with benign prostatic hyperplasia (BPH).
Tumor grade and PSA doubling time of 8 months or less were independently associated with time to any clinical failure. This was not true of tumor stage, hormone therapy duration or radiation dose.

Only hormone therapy duration and a doubling time of 8 months or less were significantly associated with time to true clinical failure.

The estimated 5-year rate of any clinical failure was 9.4 percent for men with a doubling time of more than 8 months and 60.4 percent for those with a shorter doubling time. Corresponding values for true clinical failure were 6.5 percent and 68.5 percent. For estimated 6-year overall survival after PSA failure, the proportions were 79.1 percent and 29.7 percent.

These results, Lee concluded, "further define the role of using PSA doubling time in predicting which men may have worse clinical outcomes, including decreased survival, after combination treatment with radiation and hormonal therapy, and aid in the selection of patients for more rigorous monitoring and more aggressive...therapies."

SOURCE: International Journal of Radiation, Biology, Physics, October 1, 2005.