Pathologists are the unseen and unsung heroes in cancer diagnosis and treatment. Their reports set the entire process in motion, determining in large part the treatment decisions that follow.
The pathologist is a medical doctor who has at least four years of residency training beyond the four years of medical school. The pathologist studies the slivers of prostate tissue (cores) removed during your prostate biopsy. The doctor who performed the prostate biopsy will have indicated the sites in the prostate gland from which each core was removed.
The pathologist examines the tissue samples under a microscope and records a description of each, along with the area of the prostate where it was obtained. The descriptions indicate whether the sample contains prostate tissue that is normal (benign), atypical/ suspicious, or cancer (malignant). Additional descriptions may be included. For example, a description of a benign sample may indicate “benign prostatic tissue with mild chronic inflammation” or “high-grade prostatic intraepithelial neoplasia” (PIN). Benign tissue with chronic inflammation may be a sign of prostatitis.
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The pathologist may find high-grade PIN in one or more cores. Although PIN is not prostate cancer, it is thought to be precancerous and could suggest that the biopsy may have missed an area of cancer. The current recommendation for men who have PIN in a prostate biopsy sample is careful monitoring with prostate specific antigen (PSA) testing and digital rectal examination, but they have no need for an immediate repeat biopsy.
The atypical/suspicious description is definitely a red flag. This means the pathologist could not conclusively identify the cellular patterns in the tissue and, therefore, could not rule out the presence of prostate cancer. In these instances, the biopsy slides are often sent to an outside pathologist with expertise in prostate cancer.
This is especially true if your prostate biopsy was performed in a small community hospital. In smaller hospitals, a general pathologist may examine tissue from a relatively small number of prostate biopsies each year. As with the surgeon who performs the radical prostatectomy, experience also counts when it comes to the pathologist who interprets the biopsy findings. If the atypical/suspicious finding is confirmed, then a repeat prostate biopsy should be performed, because in about 50% of cases cancer is found on the repeat biopsy.
Ideally, the slides should be sent to a major referral center with pathologists who specialize in analyzing prostate tissue. The Urologic Pathology Laboratory at Johns Hopkins gives second opinions on thousands of prostate biopsy samples each year. About a third of the original diagnoses turn out to be wrong.
When you speak with your doctor about your prostate biopsy results, be certain to ask whether there is any uncertainty about them. If the answer is yes, you can and absolutely should request that the slides be sent to a referral lab for expert review.
If one or more core samples contain malignant tissue, the pathology report will provide additional information about the prostate cancer’s aggressiveness. The least aggressive cancer cells retain a structure similar to that of normal cells and are described as well-differentiated and low grade. Moderately differentiated (intermediate-grade) cancers are disorganized and have lost many of their distinguishing features, but they retain some semblance of normal cell structure. Poorly differentiated (high-grade) cancers are distorted and bear little resemblance to normal cells.
The pathologist will assign a Gleason score to the prostate cancer by looking for specific cellular patterns in the tumor tissue. The Gleason system is based on five patterns or grades that are represented by the numbers 1 through 5. The patterns range from the most well-differentiated and normal-looking cells (Gleason pattern 1) to the most abnormal looking cells (Gleason pattern 5). The pathologist determines a man’s Gleason score by adding the Gleason grade of the most prominent pattern within the tumor (primary pattern) to the grade of the next most prominent pattern (secondary pattern). For example, if the primary pattern area is a Gleason grade 3 and the second most prominent is a Gleason grade 4, the Gleason score is 7 (3+4=7).
