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Jan. 2, 2008 -- Short-term hormone therapy to lower testosterone levels can significantly delay the progression of prostate cancer in some patients treated with radiation, a study shows.
Just four months of androgen deprivation therapy (ADT) before and during radiation was found to slow cancer growth by as much as eight years in patients with high-risk, locally advanced disease. The patients had either declined or were not considered candidates for longer-term hormonal treatment, researcher Mack Roach III, MD, of the University of California San Francisco, tells WebMD.
The findings were reported today in the American Society of Clinical Oncology (ASCO) publication Journal of Clinical Oncology.
The researchers also found no evidence of an increase in heart risk among the hormone-treated patients, compared with patients treated with radiation alone.
This finding should allay concerns about the treatment raised by a recent study, Roach tells WebMD.
In mid-October, Harvard researchers reported that short-term ADT prior to prostate cancer surgery was associated with a more than twofold increase in death from cardiovascular causes in men with localized disease.
That study did not include patients treated with ADT and radiation, and there is no clinical evidence of an increase in cardiovascular risk in these patients, Roach says.
"Our findings clearly show that the benefits [of short-term hormone treatment] outweigh the risks in this group of patients," Roach tells WebMD. "If there is an increase in heart attack risk, we didn't see it in this long-term follow-up."
The goal of ADT is to lower levels of the male sex hormones, which fuel the growth of prostate cancer.
Long-term hormone suppression of two years or more has been shown to improve survival in prostate cancer patients treated with radiation who are considered high risk due to high tumor burden, high prostate-specific antigen (PSA) scores, or other prognostic indicators.
But long-term ADT is also associated with an increased risk for osteoporosis, diabetes, and other health problems.
In an effort to assess the risks vs. benefits of shorter-term ATD, Roach and colleagues followed 456 older men with high-risk prostate cancer for 13 years.
Roughly half the men were treated with ADT for four months, immediately before and during radiation treatment. The rest of the patients were treated with radiation alone.
After about five years of follow-up, 40% of patients treated with radiation alone had cancer that had spread to the bones. It took an additional eight years for the same percentage of patients treated with ADT and radiation to develop bone metastases, says Roach.
Fewer prostate cancer deaths were reported in ADT-treated patients over 10 years of follow-up, and these men were also more likely to show no evidence of disease after 10 years.
Fatal cardiac events occurred in 12.5% of the ADT-treated patients, compared with 9.1% of the patients treated with radiation alone -- a difference that could have been due to chance.
"Men who took hormone therapy were 25% more likely to be alive after 10 years," Roach tells WebMD.
The findings confirm the long-term benefits of short-term ADT when combined with radiation, University of Michigan radiation oncology professor Howard Sandler, MD, tells WebMD.
"Even when hormone therapy is used for only four months, the benefits of hormones and radiation can last for many years," he says.
Sandler recommends two to three years of ADT for his highest-risk patients, but he says short-term hormone therapy appears adequate for patients at the higher end of the intermediate-risk scale.