CANCER OF THE PROSTATE GLAND
Incidence and Epidemiology
Prostate (see images of the prostate gland in Figures 21–1 and 21–2) cancer is the most common noncutaneous cancer detected among American men. More than 174,000 cases are detected annually (Siegel et al, 2019). Over 31,000 men die of the disease annually—the second highest burden among malignancies affecting men (Siegel et al, 2019). However, age-adjusted prostate cancer mortality at the population level has declined by roughly 50% since the mid-1990s, during a time in which men have been living longer and therefore have been more likely to reach the older ages at which prostate cancer mortality would be expected to increase. The explanation is controversial but is likely multifactorial, reflecting in large part a combination of early detection programs and improvements in treatment (Etzioni et al, 2012).
A: Schematic lateral view of the prostate. B: Cut section of the same. C: Transverse view of area shown in B.
Whole mount of prostate at level of midprostatic urethra. Note verumontanum (V) and areas of prostate cancer (CAP) in peripheral zone and areas of benign prostatic hyperplasia (BPH) in the transition zone.
These improvements in mortality have come at the cost of significant rates of overdiagnosis and overtreatment. The number of prostate cancer deaths annually is far outweighed by the number of diagnoses, and most men diagnosed ultimately die of other causes, most often cardiovascular disease (Lu-Yao et al, 2009). Of all cancers, the prevalence of prostate cancer increases the most rapidly with age. However, unlike most cancers, which have a peak age of incidence, the incidence of prostate cancer continues to increase with advancing age. The risk of latent prostate cancer (ie, detected as an incidental finding at autopsy, not related to the cause of death) by age 80 is 36% for Caucasian men and 51% for African-American men (Jahn et al, 2015). The lifetime incidence of diagnosed prostate cancer is 15%, and the mortality rate 2.9%. Thus, many prostate cancers are indolent and inconsequential to the patient while others are more virulent, and if detected too late or left untreated, they result in considerable morbidity and ultimately in death. This broad spectrum of biological activity can make decision making for individual patients difficult and highlights the critical need for accurate risk stratification of prostate cancers, which will be discussed in further detail later.
Several risk factors for prostate cancer have been identified. As discussed earlier, increasing age heightens the risk for prostate cancer. Which factors associated with the aging process are responsible for this observation is unknown. The probability of prostate cancer diagnosis in a man younger than 40 years is 1 in 10,000; for men 40–59 years old, ...