Another issue complicating comparisons of outcomes among nonconcurrent series of patients is the possibility of changes in criteria for the histologic diagnosis of prostate cancer. This phenomenon creates a statistical artifact that can produce a false sense of therapeutic accomplishment and may also lead to more aggressive therapy.
Controversy exists regarding the value of screening, the most appropriate staging evaluation, and the optimal treatment of each stage of the disease.[9,10,11];[12,13]
Incidence and Mortality
Estimated new cases and deaths from prostate cancer in the United States in 2013:[A Snapshot of Prostate Cancer]
- New cases: 238,590.
- Deaths: 29,720.
Anatomy of the male reproductive and urinary systems.
The issue of prostate cancer screening is controversial. In the United States, most prostate cancers are diagnosed as a result of screening, either with a PSA blood test or, less frequently, with a digital rectal examination. Randomized trials have yielded conflicting results.[15,16,17] Systematic literature reviews and meta-analyses have reported no clear evidence that screening for prostate cancer decreases the risk of death from prostate cancer, or that the benefits outweigh the harms of screening.[18,19]
(Refer to the PDQ summary on Prostate Cancer Screening for a detailed summary of evidence regarding the benefits and harms of screening for prostate cancer.)
More than 95% of primary prostate cancers are adenocarcinomas. Prostate adenocarcinomas are frequently multifocal and heterogeneous in patterns of differentiation. Prostatic intraepithelial neoplasia ([PIN] noninvasive atypical epithelial cells within benign appearing acini) is often present in association with prostatic adenocarcinoma. PIN is subdivided into low grade and high grade. The high-grade form may be a precursor for adenocarcinoma.
A number of rare tumors account for the remaining few percentages of cases. These include the following:
- Small-cell tumors.
- Intralobular acinar carcinomas.
- Ductal carcinomas.
- Clear cell carcinomas.
- Mucinous carcinomas.
The histologic grade of prostate adenocarcinomas is usually reported according to one of the variations of the Gleason scoring system, which provides a useful, albeit crude, adjunct to tumor staging in determining prognosis. The Gleason score is calculated based on the dominant histologic grades, from grade 1 (well differentiated) to grade 5 (very poorly differentiated). The classical score is derived by adding the two most prevalent pattern grades, yielding a score ranging from 2 to 10. Because there is some evidence that the least-differentiated component of the specimen may provide independent prognostic information, the score is often provided by its separate components (e.g., Gleason score 3 + 4 = 7; or 4 + 3 = 7).