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Prostate Cancer / Evaluation
Pathology of Prostate Cancer Ç What will your prostate biopsy reveal?
- 1. Prostatitis:
- Many prostate biopsies that are negative for carcinoma may reveal some degree of inflammation of the prostate know as prostatitis. This is of no true clinical significance and is very common in the aging male population.
- 2. Prostatic Intra-epithelial Neoplasia (PIN)
- High-grade prostatic intraepithelial neoplasia is a clinically significant finding on prostate biopsies that is associated with a presence of invasive carcinoma. Prostatic intraepithelial neoplasia (PIN) consists of architecturally benign prostatic ducts lined with cytologically atypical cells. Low grade PIN, previously referred to as mild dysplasia or PIN-1, is of no prognostic significance. Patients with low grade PIN are at no greater risk of having an invasive carcinoma found on repeat biopsy. When high-grade PIN is found on needle biopsy, there is a 30 to 50 percent risk of finding carcinoma on subsequent biopsies (Keetch et al., 1995). By itself, PIN does not give rise to elevated serum PSA levels. However, the finding of high-grade PIN without invasive carcinoma on needle biopsy, should result in subsequent additional prostatic biopsies. Biopsies should be performed both in the region where PIN was seen as well as other areas of the prostate, in the typical sextant pattern. Although high grade PIN appears to be a precursor lesion to many peripheral intermediate grade and high grade adenocarcinomas, PIN is not a required precursor for carcinomas to arise within the prostate (Epstein, 1996).
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- 3. Adenocarcinoma of the Prostate:
- Almost all cancers of the prostate are adenocarcinomas. They tend to arise from the peripheral (outer) zone of the prostate in 85 percent of cases. Adenocarcinoma of the prostate occurs in more than one site (multifocal) in more than 85 percent of cases. Even if it appears to be one-sided (unilateral) on rectal examination, these lesions occur on both sides (bilateral) in approximately 70 percent of surgical specimens that are examined pathologically. Although prostatic adenocarcinoma can be found in up to 50 percent of men in autopsy series, these lesions are small, low-grade, and clinically insignificant. These tumors are very rarely detected during clinical screening with PSA blood tests, rectal examination, and transrectal ultrasound-guided biopsy of the prostate (Walsh, 1994).
Adenocarcinomas of the prostate are graded by the pathologist according to their degree of differentiation and overall aggresiveness. They are given a Gleason Score which is a number from 2-10. Numerous grading systems have existed for evaluation and diagnosis of prostate cancer. By far, the Gleason grading system is clearly the most widely accepted. The Gleason system of prostate cancer grading is based on the glandular and cellular pattern of the tumor as evaluated at relatively low magnification. The Gleason grading system combines the two most common (primary and secondary) architectural patterns of cancer within the sampled specimen. Each of the two most common patterns is assigned a grade from one to five, with one the most differentiated and least aggressive and five the least differentiated or most aggressive pattern. The value of the Gleason grading system is its ability to predict survival rates. Importantly, Gleason grading may provide prognostic information that is to some degree independent of the extent of local tumor. Gleason sum score is reported as the two scores added together. For example, if the most common pattern of grading was a 3 pattern and the second most common pattern was a 4, the Gleason grade would be reported as Gleason 3+4=7 (Epstein et al., 1996).
- 4. Other Carcinomas of the Prostate:
- Aside from adenocarcinoma of the prostate, a biopsy of the prostate could also reveal other types of cancer. For example, mucinous adenocarcinoma are a subtype of tumor that have a very aggressive biologic behavior and tend to metatstasize early in their course. Small cell carcinoma is another type of prostate cancer formed from the hormone producing (neuroendocrine) cells of the prostate. These tend to form in men treated with long term hormonal ablation therapy but can also form on their own. Finally, transitional cell carcinoma can form in the prostate. This typically a cancer that forms in the bladder, but can also form in the portion of the bladder that lines the prostate (urothelium).
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