Treatment May Speed Prostate Cancer
Study Shows Hormone Therapy Can Make Prostate Cancer More Deadly
Nieh notes that human studies will be needed to confirm the suggestion that the cancer-stimulating effect of hormone therapy explains why the treatment often fails after succeeding at first. And he says that even if hormone therapy does stimulate cancer, its inhibitory effect is more important for some patients.
"The idea of continuous hormone therapy for very advanced prostate cancer has been with us for 60 years," Nieh says. "Patients with bone metastases and extensive disease probably have much more of the stromal part of the prostate, the part that is stimulated by androgen. So they well respond better to the cancer-inhibiting aspect of hormone treatment than to any cancer-stimulating aspect."
But the Chang team's mouse studies suggest that hormone therapy may exert a stronger effect on stromal cells early in the course of disease.
Nieh points to clinical trials of intermittent hormone therapy, in which patients go off treatment from time to time. The idea is to lessen the side effects of the treatment and to extend its anticancer effect.
"With intermittent hormone therapy, animal studies suggest you may be getting a balance between the inhibitory and stimulatory effects on the cancer, whereas continuous hormone therapy drives out the inhibitory effect and you are left with the stimulatory effect," he says. "We really won't know in humans for at least four or five years because the trial is just now being done."
Messing hopes that researchers will find a way to make future hormone therapy more specific so that it blocks the cancer-promoting functions of androgen receptors and enhances their cancer-inhibiting effects.
Chang, Messing, and colleagues report their findings in the Aug. 18 early online edition of the Proceedings of the National Academy of Sciences.