UK prostate experts agreed that capsaicin could be the basis for a future drug but they cautioned against eating too many hot peppers because of a link with stomach cancer.
In the study at Cedars-Sinai Medical Centre mice genetically modified to have human prostate cancer cells were investigated.
The animals were given a dose of pepper extract that would be equal a man of 200 pounds (90.7kg) taking 400 milligrams of capsaicin three times weekly.
This would be the equivalent of having between three and eight fresh habanera peppers, which are the highest rated peppers for capsicum content.
Dr Soren Lehmann, who led the research, said: "Capsaicin had a profound anti-proliferative effect on human prostate cancer cells in culture.
"It also dramatically slowed the development of prostate tumours."
Chris Hiley, head of policy and research at The Prostate Cancer Charity, said: "This is interesting laboratory-based work on cells but we don't yet know how, if at all, it might help men with prostate cancer.
"Eventually, it may be possible to extract the capsaicin and make it available as a drug treatment," he added.
