Larger-volume tumors of the prostate are common among older men. Available tests for the early detection of cancer have limited specificity, which necessitates a relatively high biopsy rate. The positive predictive value of combined digital rectal examination and PSA measurement has been defined, but the negative predictive value is less clear. Measurement of PSA is the most sensitive noninvasive test for prostate cancer. However, digital rectal examination detects cancer that would otherwise be missed by PSA measurement.

Clinical trials serve as one way of finding prostate cancer cures. All prostate cancer medications must take pass the three phases required to gain approval from the Food and Drug Administration.

Phase I of the clinical trials test the safety of a new drug. The second clinical phase is designed to determine how the proposed new prostate cancer treatment works. Patients are given the drug in high doses during this phase. The patients are watched to see what effect the test drug has on their prostate cancer. The final phase of clinical trial testing pits test medications against standard treatments. A control group is given dosages of the test drug while a second group uses standard methods of medicine-with the effects documented

The purpose of the trial is to test the safety and effectiveness of the technique, called high intensity focused ultrasound (HIFU), as the initial treatment in men with newly-diagnosed, localized prostate cancer.

Undiagnosed prostate cancer is highly prevalent, especially among older men [42-49]. Although many of these cancers may be considered incidental, evidence suggests that consideration of screening is warranted because earlier diagnosis of clinically significant cancers often has the potential to improve outcome [10, 12]. In fact, prostate cancer is so common among older men that selecting subpopulations for screening on the basis of risk factors other than age, such as race or family history, would not be necessary if screening and treatment strategies that favorably affect outcome were available.

However, evidence also indicates that available tests for early detection have limited specificity, particularly among older men who have benign prostatic hyperplasia. Therefore, the combined use of digital rectal examination and the currently available assays for PSA results in as many as 15 of men in their 70s requiring further invasive evaluation with biopsy. Positive predictive values are 15, depending on age.

Prostate Cancer Statistics:

Prostate cancer is the most common type of cancer found in American men, other than skin cancer. Prostate cancer is the second leading cause of cancer death in men, exceeded only by lung cancer. Although men of any age can get prostate cancer, it is found most often in men over 50. In fact, more than 70 between 1973 and 1992.

One in six American men is at lifetime risk of prostate cancer. If a close relative has prostate cancer, a man's risk of the disease more than doubles. With two relatives, his risk increases fivefold. With three close relatives, his risk is about 97 - 50 of all new cancer cases in American men.

This year, more cases of prostate cancer in men under the age of 65 are expected than the combined number of men of ages who are victims of leukemia, Hodgkin's disease, and brain tumors.

Prostate cancer accounts for approximately 15 of male cancer deaths. Yet, on average, only about 5% of federal cancer research dollars have been devoted to beat the disease.