Prostate cancer is the second most common type of cancer found in American men ( skin cancer is first). The American Cancer Society estimates that almost a quarter-million new cases of prostate cancer will be diagnosed in the US in 2005. Additionally, about 30,350 men will die of the disease this year. This makes prostate cancer the second leading cause of cancer death in men, behind only lung cancer .

Significant research dollars have been spent trying to find ways to prevent prostate cancer. One method of prevention is to identify the factors that increase a person’s risk for cancer and then develop strategies for avoiding these risk factors in the first place. Another way is to alter one of the mechanisms that cancer cells use to thrive. Certain cancers, such as prostate cancer, are driven in part by hormone levels. Hormone therapy attempts to control such cancers by reducing their response to these hormones.

A study published in the March 2005 issue of Cancer looked at the role hormone therapy with the drug finasteride may play in the prevention of prostate cancer. Finasteride disrupts the body’s manufacturing of androgen—a hormone known to be important in the growth of normal and cancerous prostate cells. Finasteride is currently used to treat benign prostatic hyperplasia (BPH) and male-pattern baldness.

About the Study

The Prostate Cancer Prevention Trial (PCPT) enrolled more than 18,000 men to determine whether finasteride reduced the risk of developing prostate cancer. Each man in the study was randomly assigned to take either five milligrams finasteride or a placebo pill daily for seven years.

At the end of the study, researchers found that a daily dose of five milligrams finasteride significantly reduced the seven-year prevalence rate of prostate cancer. In fact, finasteride reduced the prevalence rate by 25%. However, the number of men in the finasteride group who had prostate cancer with high-grade characteristics was more than double (12%) that of men taking placebo (5%). This means that the men taking finasteride who did develop prostate cancer were more likely to have cancers that would grow and spread.

The Findings

While these findings of the PCPT had been previously published, the purpose of the current study in Cancer was to weigh in on the debate surrounding the results. Critics of preventive therapy with finasteide contend that the associated increased risk for high-grade cancers cancels out the benefit of the 25% reduction in overall prevalence of the cancer. Using the PCPT data to further disect the benefits as opposed to the risks of finasteride, the study’s authors estimated the number of years of life that could be saved by administering finasteride to US men (55 and older) for a period of five years.

The authors determined that 316,760 years of life would be saved among men who took finasteride. However, when taking into account the increase in high-grade tumors, the number of years saved fell to 262,567—but this was still a significant number. Based on these calculations, the researchers concluded that the increased risk of high-grade tumors was indeed outweighed by the reduction in prostate cancer incidence.

How Does This Affect You?

Having a drug that could cause a significant reduction in the prevalence of a disease is an enticing prospect. But, when this is coupled with a slight increase in the risk of a more serious disease, the decision is not an easy one. Over 250,000 years of life saved sounds like an impressive number, but what exactly does this mean for an individual man? Ask yourself this question: would you take a drug that could decrease your risk of cancer by almost 25%, but also increase your risk of developing a severe and aggressive form of the same cancer by almost 7%?

Balancing the individual benefits and risks involved in preventing or treating a serious disease is an important and necessary step that must be taken. Patients who have already been diagnosed with cancer are usually willing to accept certain risks with their treatment. Men with no cancer, however, would reasonably wish to avoid any risk at all, since they may never develop the disease, with or without finasteride. This is why the widespread use of finasteride for the prevention of prostate cancer in healthy men is unlikely to be recommended soon, despite the favorable conclusions of this study.