Prostate adenocarcinoma is the second most common non-skin cancer, and the second most common cause of cancer death in men in the U.S. — with 198,100 new cases and 31,500 deaths being forecast for 2001.1 A white man has a 13.8 percent risk and a black man a 12.5 percent risk of having prostate cancer diagnosed during his lifetime.2 Approximately 70 percent of prostate cancers form in the peripheral zone. The unique metabolism of this tissue leads to the synthesis and secretion of large amounts of citrate. The transition zone, which is the site of benign prostatic hyperplasia, accounts for 20 percent of prostate cancers and the central zone for only 10 percent.

The management of prostate cancer is determined by the stage and grade* of the tumor and the serum concentration of prostate specific antigen (PSA) (see box page 62). Imaging is important in determining stage, in directing biopsies to confirm the presence of cancer and assess its grade, and in many current forms of management.

Does he have cancer?
Transrectal ultrasonography (TRUS), often in a urologist’s office, is the standard method of imaging possible prostate cancer. The examination is performed in the axial and sagittal planes with a high-frequency transducer, and the volume of the gland is estimated.4,5

Unfortunately, prostate cancer does not produce predictable sonographic changes. Between 60 percent and 70 percent of these cancers are hypoechoic, but some benign conditions also produce hypoechoic areas, and the positive predictive value (PPV) of this finding is no greater than 52 percent.4 As many as 40 percent of prostate cancers are isoechoic and thus invisible by TRUS.4 Moreover, only tumors in the peripheral zone can be imaged reliably.4 The deficiencies of the examination were summarized with the comment that “specificity and sensitivity of conventional grey-scale TRUS for the detection of prostate cancer are disappointingly low.”6 However, TRUS is critical to accurate tissue sampling during biopsy.7 Abnormal areas are sampled, and sextant biopsies are acquired to ensure examination of all areas of the gland.

Please refer to the October 2002 issue for the complete story. For information on article reprints, contact Martin St. Denis