Scientists continue to look at new ways to prevent, treat, and diagnose prostate cancer. Research has already led to a number of advances in these areas. Dietary Research Several studies are under way to explore the causes of prostate cancer. Some researchers think that diet may affect a man's chances of developing prostate cancer. For example, some studies show that prostate cancer is more common in populations that consume a high-fat diet, particularly animal fat, and in populations with diets that lack certain nutrients. Research on Testosterone Some research suggests that high levels of testosterone may increase a man's risk of prostate cancer. The difference in prostate cancer risk among racial groups could be related to high testosterone levels, but it also could result from diet or other lifestyle factors. Genetic Research Researchers are studying changes in genes that may increase the risk for developing prostate cancer. Some studies are looking at the genes of men who were diagnosed with prostate cancer at a relatively young age, such as less than 55 years old, and the genes of families who have several members with the disease. Other studies are trying to identify which genes, or arrangements of genes, are most likely to lead to prostate cancer. Much more work is needed, however, before scientists can say exactly how genetic changes relate to prostate cancer. Prevention Research Several studies have explored ways to prevent prostate cancer. In October 2008, initial results of a study on the use of the dietary supplements vitamin E and selenium found that they did not provide any benefit in reducing the number of new cases of the disease. A few studies suggest that a diet that regularly includes tomato-based foods may help protect men from prostate cancer, but there are no studies that conclusively prove this hypothesis. According to results of a study that was re-analyzed in 2013, men who took finasteride, a drug that affects male hormone levels, reduced their chances of getting prostate cancer by nearly 30 percent compared to men who took a placebo. Unlike earlier findings from this study, this new analysis showed no increased risk of late stage disease due to use of finasteride. Stopping Prostate Cancer from Returning Scientists are also looking at ways to stop prostate cancer from returning in men who have already been treated for the disease. These approaches use drugs such as finasteride, flutamide, nilutamide, and LH-RH agonists that manipulate hormone levels. In 2010, the FDA approved a therapeutic cancer vaccine, Provenge, for use in some men with metastatic prostate cancer. Provenge may provide a 4-month improvement in overall survival compared with a placebo vaccine. Other similar vaccine therapies are in development. Research on New Blood Tests Some researchers are working to develop new blood tests to detect the antibodies that the immune system produces to fight prostate cancer. When used along with PSA testing, the antibody tests may provide more accurate results about whether or not a man has prostate cancer. Researching New Approaches to Treatment Through research, doctors are trying to find new, more effective ways to treat prostate cancer. Cryosurgery -- destroying cancer by freezing it -- is under study as an alternative to surgery and radiation therapy. To avoid damaging healthy tissue, the doctor places an instrument known as a cryoprobe in direct contact with the tumor to freeze it. Doctors are studying new ways of using radiation therapy and hormonal therapy, too. Studies have shown that hormonal therapy given after radiation therapy can help certain men whose cancer has spread to nearby tissues. Scientists are also testing the effectiveness of chemotherapy and biological therapy for men whose cancer does not respond, or stops responding, to hormonal therapy. They are also exploring new ways to schedule and combine various treatments. For example, they are studying hormonal therapy to find out if using it to shrink the tumor before a man has surgery or radiation might be a useful approach. For men with early stage prostate cancer, researchers are also comparing treatment with watchful waiting. The results of this work will help doctors know whether to treat early stage prostate cancer immediately or only later on, if symptoms occur or worsen.