Heart drug may fight prostate cancer

An old drug may have may have a new use, according to a recent study. Research published in the journal Cancer Discovery suggests that digoxin (Lanoxin), a drug long used to treat heart failure and heart rhythm abnormalities, may control prostate cancer.

Investigators at Johns Hopkins conducted a two-part study to explore whether drugs currently on the market for other conditions could treat prostate cancer. They first screened 38 non-chemotherapy drugs from a database of more than 3,100 compounds to see if they had any effect on cancer. Digoxin reduced the growth of prostate cancer cells in the laboratory by 50%.

Next, the researchers examined the impact of digoxin use in 47,884 men between the ages of 40 and 75 who participated in the Health Professionals Follow-up Study from 1986 through 2006. At the start of the study, none of the participants had cancer, and 2% of them reported regularly using digoxin.

After 20 years, some 5,000 cases of prostate cancer had been reported. The digoxin users had a 25% lower risk of prostate cancer than nonusers, and the risk was lower still among men who had used the drug for 10 years or longer. Even after accounting for family history of prostate cancer, use of additional heart medications, and other factors, the reduction in prostate cancer risk held up.

Although the findings are promising, they come with caveats. First, researchers aren’t exactly sure how digoxin exerts its anticancer effect, knowledge that’s needed to declare it a therapy for prostate cancer. And because the study does not prove that digoxin prevents prostate cancer, giving it to healthy people for that purpose poses risks. The drug can cause serious side effects including an irregular heartbeat and breast enlargement, as well as nausea, vomiting, and headaches. However, additional research may yield other compounds that work in a similar way while causing fewer side effects.

Because digoxin treats heart failure and heart rhythm problems, it’s possible that men who take the drug don’t live as long as other men. Although the researchers made no note of this, “it is possible that digoxin users in the study had a shortened lifespan, decreasing the amount of time available for them to develop prostate cancer,” said Marc B. Garnick, editor in chief of Harvard Health Publishing’ Annual Report on Prostate Diseases. “These analyses are difficult to fully interpret and should serve as a basis for further studies.”

Source: Platz EA, Yegnasubramanian S, Liu J, et al. A Novel Two-Stage, Transdisciplinary Study Identifies Digoxin as a Possible Drug for Prostate Cancer Treatment. Cancer Discovery 2011;1:OF67-75.

Posted May 17, 2011.