Prostate Cancer: Overview and Risk Factors
Prostate cancer is the second most common malignancy in men in the United States; only skin cancer occurs more frequently. Although most cases progress slowly and may never become clinically apparent, the disease is the second-leading cause of cancer death in men and the most common cause of cancer death in male nonsmokers. Further, because of its strong association with age, the number of new cases and deaths from prostate cancer is expected to increase with the aging of the population.
Nearly all prostate cancer cases are adenocarcinomas, with a few isolated instances of transitional cell carcinoma. Hormonal factors are important in the etiology of prostate cancer. Research studies have shown strong associations with testosterone and insulin-like growth factor I (IGF-I).
Symptoms often include dysuria, difficulty voiding, urinary frequency and retention, and hematuria. However, more than 80% of cases are asymptomatic and present only with an elevated prostate-specific antigen (PSA) level or hard nodule on digital rectal examination.
The most common sites of metastasis are lymph nodes and bone. A small number of cases present with symptoms of metastatic disease, such as vertebral back pain, renal failure due to ureteral obstruction, and weight loss.
Age. Prevalence increases rapidly with age. The condition rarely occurs before age 45, whereas most men over 80 years show microscopic evidence of malignant cells.
Race. African American men have the highest risk of prostate cancer of any demographic group. They also tend to have higher serum PSA levels and more advanced disease at diagnosis.
Genetics. Prostate cancer is likely influenced by several genetic factors. Men who have a first-degree relative with prostate cancer are twice as likely to develop the disease themselves. Early onset of prostate cancer in a first-degree family member further increases the risk. A smaller number of CAG repeats in the gene coding for the androgen receptor has been associated with increased risk. The incidence of prostate cancer is higher in families with breast cancer, and patients with BRCA1 or BRCA2 mutations appear to have a 2-fold to 5-fold increased risk.
High blood concentrations of IGF-I. IGF-I concentrations are associated with cancer risk, and are influenced by body weight and with certain dietary intakes, as described in Nutritional Considerations.
Prostate Cancer: Diagnosis and Treatment >>