39-17: Prostate Cancer

GENERAL CONSIDERATIONS

Prostate cancer is the most common noncutaneous cancer and the second leading cause of cancer-related death in American men with an estimated 191,930 new prostate cancer diagnoses and 33,330 prostate cancer deaths in 2020. The clinical incidence, however, does not match the prevalence of the disease. Autopsy studies have demonstrated that more than 40% of men over age 50 years have prostate cancer, and its prevalence increases with age with 30% of men aged 60–69 years and 67% of men aged 80–89 years harboring the disease at autopsy. Most of these occult cancers are small indolent organ-confined cancers with few representing regional or metastatic disease. Although the global prevalence of prostatic cancer at autopsy is relatively consistent, the clinical incidence varies considerably (high in North America and European countries, intermediate in South America, and low in the Far East), suggesting that environmental or dietary differences among populations may be important for prostatic cancer growth. A 50-year-old American man has a lifetime risk of 40% for latent cancer, a 16% risk for developing clinically apparent cancer, and a 2.9% risk of death due to prostatic cancer. Black race, family history of prostatic cancer, and history of high dietary fat intake are risk factors for prostate cancer.

CLINICAL FINDINGS

A. Symptoms and Signs

Presently, most prostate cancers are asymptomatic and are diagnosed because of elevations in serum PSA. However, some men will be diagnosed based on discrete nodules or areas of induration within the prostate on a DRE. Obstructive voiding symptoms are most often due to benign prostatic hyperplasia, which occurs in the same age group. Nevertheless, large or locally extensive prostatic cancers can cause obstructive voiding symptoms, including urinary retention. Lymph node metastases can lead to lower extremity lymphedema. Because the axial skeleton is the most common site of metastases, patients may present with back pain, pathologic fractures, or rarely neurologic symptoms from epidural metastases and cord compression.

B. Laboratory Findings

1. Serum tumor markers

PSA is a glycoprotein produced only by prostatic cells, either benign or malignant. The serum level is typically low and correlates with the total volume of prostate tissue and tends to increase with age. Measurement of serum PSA is useful in detecting and staging prostate cancer, monitoring response to treatment, and identifying recurrence before it becomes clinically evident. As a screening test, PSA is elevated (greater than 4.0 ng/mL [4.0 mcg/L]) in 10–15% of men. Prostate cancer will be diagnosed in approximately 18–30% of men with PSA 4.1–10 ng/mL (4.1–10 mcg/L) and 50–70% of men with PSA greater than 10 ng/mL (10 mcg/L). However, no PSA threshold excludes the diagnosis of prostate ...