The concentration of prostate specific antigen achieved by the end of a seven-month course of hormone therapy predicts survival of patients with advanced prostate cancer, according to an article in the August 20 issue of the Journal of Clinical Oncology.

The new multicenter US study was conducted by the Southwest Oncology Group and led by researchers at the University of Michigan Comprehensive Cancer Center.

The study evaluated 1,345 men with metastatic prostate cancer who were treated with seven months of androgen deprivation therapy. Prostate specific antigen levels were monitored throughout treatment. Men whose antigen level dropped below 4.0 ng/mL had one quarter the risk of dying compared with patients whose antigen level was more than 4.0.

“Our analysis showed that a low or undetectable prostate specific antigen after seven months of androgen deprivation therapy is a powerful predictor of risk of death in patients with new metastatic prostate cancer. This could allow oncologists to identify patients who are unlikely to do well with this treatment long before they develop clinical signs of treatment resistance,” sad lead study author Maha Hussain, MD.

After the seven-month course of therapy, 69 percent of men maintained a prostate specific antigen level of less than 4.0 ng/mL, and 43 percent had an undetectable level.

Patients whose prostate specific antigen level was higher than 4.0 at the end of treatment survived 13 months, while patients whose level dropped below 4.0 but above 0.2 lived 44 months and those whose antigen level was undetectable (below 0.2 ng/mL) lived 75 months.

The men in the study were enrolled in a Phase III trial in which they would receive additional treatment after the seven months of initial hormone therapy. The patient’s prostate specific antigen level before beginning treatment had t be at least 5.0 ng/mL to qualify.

“What is attractive about using prostate specific antigen to predict survival in metastatic prostate cancer is that it is an easily measurable factor. These findings could help patients avoid ineffective treatment and could help researchers design further trials,” Hussain said.