DIAGNOSIS & BIOPSY
Abnormal screening results may indicate that further testing is needed. A diagnosis of prostate cancer is achieved through an ultrasound-guided biopsy of the prostate gland. A prostate biopsy is conducted with a transrectal ultrasound and biopsy needle to collect small slivers of prostate tissue that are analyzed for cancer. This tissue is then examined under a microscope for cancer cells. A biopsy of the prostate can be performed in the physician’s office and patients usually return home the same day. Keep in mind that it is still possible to have cancer, even if the biopsy is negative, because the cancer cells may not have progressed enough to be detected by a microscope or the biopsy may miss the areas of cancer within the prostate.
PROSTATE CANCER GRADING & PROGNOSTIC SCORING
Gleason Score: When prostate cancer is found in the biopsy a pathologist assigns a Gleason Score. A Gleason Score helps to communicate the aggressiveness of the cancer.
- To calculate a Gleason Score the pathologist looks at the largest area of cancer found on biopsy. Prostate cancers often have areas with different grades, so a grade is assigned to the two areas that make up most of the cancer. The first number listed is the grade that is most common in the tumor. For instance, if the Gleason Score is written as 3+4=7, it means most of the tumor is grade 3 and less is grade 4 and they are added for a Gleason Score.
- If the cancerous tissue looks much like normal prostate tissue, a grade or a number 1 is assigned. If cancer cells and their growth patterns look very abnormal, a grade of 5 is assigned.
- The lowest a Gleason Score can be is 3+3=Gleason Score 6. Most cancers found on a biopsy are grade 3 or higher.
- The highest a Gleason Score can be is 5+5=Gleason Score 10.
- The higher the Gleason Score, the more likely it is that your cancer will grow and spread quickly.
- Grades of 6 or less mean that the cancer cells look fairly similar to your normal cells, and the cancer is likely to be less aggressive.
- Grades of 7 are in the intermediate range. This means that the cancer cells do not look like normal cells, and are more likely to be aggressive and grow faster.
- Grades 8 to 10 indicate that the cancer cells are more likely to be very aggressive in growth.
New Prostate Cancer Grading System: The New Prostate Grading System is the future and an extension of the current Gleason grading scale for determining the stage of prostate cancer.
Designed to Provide:
- A more accurate grade stratification than the current Gleason system.
- A simplified grading system with 5 categories.
- Better represent low grade disease with the potential to reduce over treatment of indolent prostate cancer.
The new system is based on the basic premise that prostate cancers can be subdivided based on pathological characteristics into five categories described in the table below.
- My Gleason Score Looks Different:
Other ways that this Gleason Score may be listed in your report are Gleason 7/10, Gleason 7 (3+4) or combined Gleason Grade of 7.
- What does it mean to have a Gleason Score of 6 or 7 or 8-10?
-The lowest Gleason Score of a cancer found on a prostate biopsy is 6. These cancers may be called well-differentiated or low-grade and are
likely to be less aggressive - they tend to grow and spread slowly.
-Cancers with Gleason Scores of 8 to 10 may be called poorly differentiated or high grade. These cancers tend to be aggressive, meaning they
are likely to grow and spread more quickly.
-Cancers with a Gleason Score of 7 may be called moderately differentiated or intermediate grade. The rate at which they grow and spread
tends to be in between the other 2.
- What does it mean when there are different core samples with different Gleason Scores?
Cores may be samples from different areas of the same tumor or different tumors in the prostate. Because the grade may vary within the same tumor or between different tumors, different samples (cores) taken from your prostate may have different Gleason Scores. Typically, the highest (largest number) Gleason Score will be the one used by your doctor for predicting your prognosis and deciding treatment.
- Can the Gleason Score on my biopsy really tell what the cancer grade is in the entire prostate?
Because prostate biopsies are tissue samples from different areas of the prostate, the Gleason Score on a biopsy usually reflects your cancer's true grade. However, in about 20% of cases the biopsy grade is lower than the true grade because the biopsy misses a higher grade (more aggressive) area of the cancer. It can work the other way, too, with the true grade of the tumor being lower than what is seen on the biopsy.
How Important Is the Gleason Score?
The Gleason Score is very important in predicting the behavior of a prostate cancer. Still, other factors are also important such as:
- The PSA Level
- Findings on a rectal exam
- How much of each core is made up of cancer
- The number of cores that contain cancer
- Whether cancer was found in both sides of the prostate
- Whether the cancer has spread outside the prostate
What does it mean if my biopsy mentions that there is perineural invasion?
Perineural invasion means that cancer cells were seen surrounding or tracking along a nerve fiber with the prostate. When this is found on a biopsy, it means there is a higher chance that the cancer has spread outside the prostate. Still, perineural invasion does not mean that the cancer has spread, and other factors, such as the Gleason Score and amount of cancer in the cores are more important. In some cases, findings perineural invasion may affect treatment, so if your report mentions perineural invasion, you should discuss it with your doctor.
What does it mean if my biopsy report also says high-grade prostatic intraepithelial neoplasia or high-grade PIN?
High-grade prostatic intraepitherlial neoplasia (or high-grade PIN) is a pre-cancer to the prostate.
What does it mean if, in addition to cancer, my biopsy report also says atypical glands or atypical small acinar proliferation (ASAP) or glandular atypia or atypical grandular proliferation?
All of these terms mean that the pathologist saw something under the microscope that is worrisome for cancer, but he or she is not 100% sure that cancer is present.
What does it mean if in addition to cancer my biopsy report also says acute inflammation (acute prostatitis) or chronic inflammation (chronic prostatitis)?
Inflammation of the prostate is called prostatitis. Most cases of prostatitis reported on a biopsy are not caused by infection and do not need to be treated. In some cases, inflammation may increase you PSA level, but it is not linked to prostate cancer. The finding of prostatitis on a biopsy of someone with cancer does not affect their prognosis or the way the cancer is treated.
AJCC TNM Staging: A staging system is a standard way for the cancer care team to describe how far a cancer has spread. This is the most widely used staging system for prostate cancer. The TNM system for prostate cancer is based on 5 key pieces of information.
- The extent of the primary tumor (T category)
- Whether the cancer has spread to nearby lymph nodes (N category)
- The absence or presence of distant metastasis (M category)
- The PSA level at the time of diagnosis
- The Gleason Score, based on the prostate biopsy (or surgery)
There are actually 2 types of staging for prostate cancer:
- The clinical stage is your doctor's best estimate of the extent of your disease, based on the results of the physical exam (including DRE), lab tests, prostate biopsy and any imaging tests you have had.
- If you have surgery, your doctors can also determine the pathologic stage, which is based on the surgery and examination of the removed tissue. This means that if you have surgery, the stage of your cancer might actually change afterward (if cancer was found in a place it was not suspected, for example). Pathologic staging is likely to be more accurate than clinical staging, as it allows your doctor to get a firsthand impression of the extent of your disease. This is one possible advantage of having surgery (radical prostatectomy) as opposed to radiation therapy or active surveillance.
In recent years a new prostate biopsy method has emerged called a Staging or Mapping Biopsy. This method of biopsy is similar to the standard transrectal ultrasound needle biopsy is an outpatient surgical procedure in which a transrectal ultrasound biopsy where 12 biopsy samples are taken. However, this procedure is performed as an outpatient procedure under general anesthesia. A physician places a grid below the patient’s scrotum and takes between 35- 80 biopsies of the prostate. This procedure allows the entire prostate to be biopsied and allows the physician to create a three-dimensional image of the prostate, including the location of the cancers within the gland. This biopsy may better determine the size and locations of the cancer, and allow patients and their physicians to more appropriately select a treatment option, including ongoing evaluation. This method of biopsy may help to eliminate the under- and over- grading of prostate cancer leading to patients undergoing treatments that are unnecessarily invasive or being subjected to the risk of associated morbidities from other treatment methods.