Clinical outcome for patients with prostate cancer treated with hormone and radiation therapy can be predicted by how rapidly the prostate specific antigen (PSA) level rises after treatment, according to an article in the October 1 issue of the International Journal of Radiation Oncology*Biology*Physics.

Doctors at M.D. Anderson Cancer Center in Houston studied 621 men with prostate cancer treated with hormone and radiation therapy between 1989 and 2003 to determine whether clinical failure after treatment correlated with the speed at which their post-treatment PSA level rose. Clinical failure was defined as cancer recurrence in the prostate or metastasis to other parts of the body.

Researchers found that measuring how quickly the PSA level doubled was a good indicator of subsequent poor clinical outcomes, including development of metastatic cancer or death related to prostate cancer.

The key interval was 8 months: Patients whose PSA level doubled within 8 months after treatment were more likely to develop recurrent or metastatic disease than patients whose PSA did not double in that time interval.

The estimated five-year rate of clinical failure for patients with a PSA doubling time of more than 8 months was only 9.4 percent, whereas 60.4 percent of patients whose PSA doubling time was less than or equal to 8 months could expect some type of clinical failure.

“The PSA doubling time is an important indicator of how well a patient will recover from prostate cancer,” said Andrew K. Lee, MD, lead author of the study and a radiation oncologist at M.D. Anderson Cancer Center. “Although clinical outcomes may be positively affected if the patient receives hormone therapy with radiation therapy, a quickly rising PSA level unfortunately still portends poor results for these patients.”