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).
There is evidence that, over time, pathologists have tended to award higher Gleason scores to the same histologic patterns, a phenomenon sometimes termed "grade inflation."[23,24] This phenomenon complicates comparisons of outcomes in current versus historical patient series. For example, prostate biopsies from a population-based cohort of 1,858 men diagnosed with prostate cancer from 1990 through 1992 were re-read in 2002 to 2004.[23,24] The contemporary Gleason score readings were an average of 0.85 points higher (95% confidence interval, 0.79–0.91; P < .001) than the same slides read a decade earlier. As a result, Gleason-score standardized prostate cancer mortality rates for these men were artifactually improved from 2.08 to 1.50 deaths per 100 person years—a 28% decrease even though overall outcomes were unchanged.