How well did the radiation treatment work? Radiation oncologists Phuoc Tran, M.D., Ph.D., and Theodore DeWeese, M.D., believe measuring a man’s PSA at the end of treatment may provide a strong clue. “Emerging literature suggests that the PSA response to androgen deprivation therapy (ADT) before radiation may help identify men with disease that is more aggressive,” he says. “Similarly, in men undergoing definitive radiation for localized prostate cancer, the PSA response at the end of treatment may serve as a helpful biomarker.”

This end-of-radiation (EOR) PSA measurement may turn out to be a more helpful marker for guiding treatment strategies than the PSA level before radiation, Tran continues, “and may also be applicable to men undergoing definitive radiation alone. At our institution, it has been the standard practice to obtain an EOR PSA during the last week of treatment. This was instituted by Ted DeWeese when he first began his practice.” Tran and colleagues including DeWeese, Danny Song, M.D., Curtiland Deville, M.D., Stephen Greco, M.D., and Amol Narang, M.D., recently examined the value of the EOR PSA in a group of nearly 700 men with long-term follow-up, average of 11 years, after being treated at Hopkins with definitive radiation for prostate cancer.

“We found that the PSA level during the last week of radiation can predict survival in patients undergoing radiation therapy for prostate cancer,” Tran says. Men who had a detectable EOR PSA after definitive radiation for localized prostate cancer had poorer prognoses. “Notably, men with intermediate- or high-risk disease who underwent neoadjuvant-concurrent ADT who achieved an undetectable EOR PSA level were more likely to live longer and not die of their prostate cancer.” More studies are needed to validate these results, and to investigate the potential use of the EOR PSA in determining the best treatment for men with localized prostate cancer.