Carcinoma of the prostate is the most common tumor in men in the United States, with an estimated 238,590 new cases and 29,720 deaths expected in 2013. 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.
After a gastrointestinal stromal tumor has been diagnosed, tests are done to find out if cancer cells have spread within the gastrointestinal tract or to other parts of the body.
The process used to find out if cancer has spread within the gastrointestinal (GI) tract or to other parts of the body is called staging. The information gathered from the staging process determines the stage of the disease. The following tests and procedures may be used in the staging process:
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.