Carcinoma of the prostate is the most common tumor in men in the United States, with an estimated 233,000 new cases and 29,480 deaths expected in 2014. A wide range of estimates of the impact of the disease are notable. The disease is histologically evident in as many as 34% of men in their fifth decade and in up to 70% of men aged 80 years and older.[2,3] Prostate cancer will be diagnosed in almost one-fifth of U.S. men compared with about 3% of men who will be expected to die of the disease. The estimated reduction in life expectancy of men who die of prostate cancer is approximately 9 years.
Note: Separate PDQ summaries on Oral Cancer Prevention and Lip and Oral Cavity Cancer Treatment are also available.
There is inadequate evidence to establish whether screening would result in a decrease in mortality from oral cancer.
Magnitude of Effect: No evidence of benefit or harm.
Study Design: Evidence obtained from one randomized controlled trial.
Internal Validity: Poor.
Consistency: Not applicable (N/A).
The extraordinarily high rate of clinically occult prostate cancer in the general population compared with the 20-fold lower likelihood of death from the disease indicates that many of these cancers have low biologic risk. Concordant with this observation are the many series of patients with lower-risk (i.e., Gleason 6 and some low-volume Gleason 7 tumors) prostate cancer managed by surveillance alone with high survival rates at 5 and 10 years of follow-up. Data demonstrate, however, that with longer follow-up, higher-grade cancers are associated with a greater risk of prostate cancer death.[7,8]
Because of marked variability in tumor differentiation from one microscopic field to another, many pathologists will report the range of differentiation among the malignant cells that are present in a biopsy using the Gleason grading system. This grading system includes five histologic patterns distinguished by the glandular architecture of the cancer. The architectural patterns are identified and assigned a grade from 1 to 5 with 1 being the most differentiated and 5 being the least differentiated. The sum of the grades of the predominant and next most prevalent will range from 2 (well-differentiated tumors) to 10 (undifferentiated tumors).[9,10] Systematic changes to the histological interpretation of biopsy specimens by anatomical pathologists have occurred during the prostate-specific antigen (PSA) screening era (i.e., since about 1985) in the United States. This phenomenon, sometimes called "grade inflation," is the apparent increase in the distribution of high-grade tumors in the population for a period of time but in the absence of a true biological or clinical change. It is possibly the result of an increasing tendency for pathologists to read tumor grade as more aggressive, resulting in a higher preponderance to treat these cancers aggressively.