Study: When/if to start hormones for prostate cancer patients whose PSA rises after radiation

September 23, 2008

A new Fox Chase Cancer Center study suggests men with early stage prostate cancer treated with radiation therapy should begin hormone therapy immediately if their PSA level rises quickly and doubles within six months at any time after treatment. The study also supports foregoing hormones if the PSA doesn't rise as quickly. Both findings suggest a change in the practice of prescribing hormones is warranted.

After treatment for prostate cancer, many men will experience fluctuations or bounces in their PSA level, but for some the PSA continues to rise and doesn't return to its lowest point immediately after treatment. Knowing if or when to recommend hormone treatment (androgen deprivation therapy) depends on how much and how quickly the PSA rises – called the PSA doubling time. Hormone therapy has been shown to kill cancer cells and improve survival, but it carries a risk of side effects.

"We've been using PSA doubling time to help guide our decision about when to begin hormone therapy, but this study gives us new and critical information that suggests we should start therapy sooner than previously thought for some patients and delay treatment for others," explains Eric Horwitz, M.D., acting chairman and clinical director of the radiation oncology department at Fox Chase, who led the study. "While hormone therapy can have side effects such as hot flashes, decreased libido and osteoporosis, it can help prevent the cancer from spreading to the bones, causing pain and leading to an earlier death from the disease."

Previous studies indicated an increased likelihood that the cancer had spread if the PSA doubling time occurred within 12 months, and thus a potential benefit from receiving hormone therapy. But recently, a newly validated formula, known as the Phoenix definition, used by physicians demonstrates a more accurate way of determining biochemical failure, a term used to describe a significant rise in PSA. Using the new formula, the Fox Chase team was able to determine when earlier action needs to be taken.

"What we now know is that when the PSA rises and doubles within 6 months, versus 12 months, we need to act," explains Horwitz. "Our study suggests that these are the men who will benefit most from hormone therapy." Horwitz's research was presented today at the 50th annual meeting of the American Society for Therapeutic Radiology and Oncology.

Also, Horwitz says the study helps identify who is less likely to benefit from hormone therapy which may indicate a necessary change in current practice.

"Men whose PSA rises, but does so over a longer period of time may not benefit from hormones.

"These results further refine the role of PSA doubling time in predicting which patients may benefit from hormone therapy and which patients may be observed expectantly and spared the toxicity of the hormones," Horwitz concludes.

Source: Fox Chase Cancer Center