Few studies have been conducted examining the long-term (8-10 years) efficacy of external beam radiation treatment for prostate cancer until now. Researchers at Fox Chase Cancer Center have published a study in the May issue of the journal Urology which suggests patients treated with radiation therapy, who are disease-free at four years, remain disease-free.
"'Cure' is a powerful word when talking about the treatment of cancer, but this research allows us to discuss radiation treatment of prostate cancer in that context," explains Alexandra L. Hanlon, Ph.D., lead author of the paper. "We can comfortably tell a patient that if he remains disease-free after four years, the chances of his cancer coming back are incredibly slim."
According to the study, patients treated with external beam radiation alone or in combination with short-term hormone therapy (androgen deprivation) show little risk of failure after four years. Ninety-nine percent of patients who show no evidence of recurrence five years after their treatment, remain disease-free. None of those patients recurred after six years. The research shows that if radiation treatment fails, as indicated by rising PSA levels, it does so in the first three to four years following treatment. The median biochemical follow-up was 69 months for patients receiving radiation alone and 60 months for the adjuvant hormone patients. All patients had at least five years follow-up.
In addition, the study shows that patients with a more favorable prognosis attain a lower risk of treatment failure sooner than patients with a less favorable prognosis.
"If radiation treatment fails, it happens earlier for men who had a higher PSA level before undergoing radiation therapy," Hanlon explains.
The risk of failure is greatest between 12 and 36 months, tapering to a low rate of failure at four years. Treatment for men with an initial PSA of up to 10 failed at a median of 28 months. Treatment for men with an initial PSA of 10 to 19.9 failed at a median of 25 months. And treatment for men with an initial PSA of 20 and higher failed at a median of 22 months. The latter group reaches low levels of disease recurrence at six years. In contrast, patients who have a PSA level of less than 20 before treatment are less likely to recur beyond four years after treatment.
Patients treated with external beam radiation and hormone therapy (androgen deprivation) show a different pattern of failure, but a similar time frame for attaining a low risk of treatment failure. The highest risk of failure occurs immediately following treatment, but declines to a low risk of failure at 48 months.
Fox Chase Cancer Center, one of the nation's first comprehensive cancer centers designated by the National Cancer Institute in 1974, conducts basic and clinical research; programs of prevention, detection and treatment of cancer; and community outreach. For more information about Fox Chase activities, visit the Center's web site at: www.fccc.edu .