Could Nitroglycerin Stop Prostate Cancer?
A low dose of nitroglycerin, the little pill people pop under their tongue when they experience angina, may slow or even stop the progression of prostate cancer. Researchers at Queen’s University are the first to conduct a clinical trial using nitroglycerin to treat prostate cancer.
Nitroglycerin has been used for more than 100 years to treat angina. When people take nitroglycerin, the drug is converted into nitric oxide, a substance that causes the blood vessels to relax and widen and increase blood flow. Previous research by scientists at Queen’s University revealed that a decline in nitric oxide has an impact on tumor progression, and that this progression can be stopped by a low-dose of nitroglycerin.
This finding prompted the investigators to explore the possible role of nitroglycerin in the treatment of prostate cancer. The 24-month, Phase II study included 29 men who had increasing levels of prostate-specific antigen (PSA) after they had undergone prostate surgery or radiation. Clinicians monitor PSA levels to help predict progression of the disease.
All of the men were treated with a low-dose, slow-release nitroglycerin skin patch and had their PSA levels monitored. The rate of disease progression stopped or decreased in 16 of the 17 patients who completed the study. Disease progression was determined by using the PSA doubling time test, a tool that allows clinicians to calculate the rate of rise in PSA levels, expressed as the velocity in nanograms per milliliter per year (PSA doubling time) in months or years.
Although prostate surgery or radiotherapy is successful in many men, a rise in PSA after treatment, a so-called biochemical recurrence, occurs in 30 to 50 percent of patients. Thus there is a great need for an effective, noninvasive treatment for these men. The study’s authors are encouraged by the apparent ability of nitroglycerin to stop progression of prostate cancer, and they plan to begin broader clinical trials in 2010 to verify and expand upon their results.