Understanding Your Biopsy Report
What Is a Prostate Biopsy?
A prostate biopsy is a procedure in which a urologist removes small tissue samples from the prostate gland using a thin needle. These samples — called cores — are sent to a pathology laboratory where a pathologist examines them under a microscope to look for cancer cells.
A standard biopsy typically takes 12 cores from different areas of the prostate. Targeted biopsies, guided by MRI imaging, may take additional cores from suspicious areas identified on imaging.
Reading Your Pathology Report
Your biopsy report can look intimidating at first glance. Here is a breakdown of the key terms you are likely to encounter:
Adenocarcinoma
The most common type of prostate cancer. If your report says 'adenocarcinoma of the prostate,' this confirms cancer is present. It means the cancer started in the gland cells of the prostate.
Gleason Score / Grade Group
A grading system that describes how aggressive the cancer cells look under the microscope. This is one of the most important pieces of information in your report. See the separate guides on Understanding Gleason Score and Understanding Grade Groups for a full explanation.
Number of Positive Cores
Reported as a fraction — for example, '3 of 12 cores positive.' This tells you how many of the tissue samples contained cancer. More positive cores generally indicate more extensive disease. See Understanding Positive Biopsy Cores for more detail.
Percent Involvement
The percentage of each core (or all cores combined) that contains cancer. For example, '40% involvement' means cancer occupied 40% of the tissue in that core. See Understanding Percent Involvement for more detail.
Perineural Invasion (PNI)
Indicates that cancer cells were found growing along or around nerve fibers in the prostate. See Understanding Perineural Invasion for a full explanation.
Cribriform Pattern
A specific architectural pattern of cancer cells that is associated with more aggressive disease. See Understanding Cribriform Pattern for a full explanation.
High-Grade PIN (Prostatic Intraepithelial Neoplasia)
Abnormal cells that are not yet cancer but may be a precursor. High-grade PIN in a biopsy may prompt closer monitoring or repeat biopsy.
ASAP (Atypical Small Acinar Proliferation)
Cells that look suspicious but do not meet the criteria for a definitive cancer diagnosis. ASAP findings typically lead to a repeat biopsy.
You have the right to receive a copy of your pathology report. Reading it alongside these guides — and bringing your questions to your next appointment — can help you feel more prepared and in control.
Location Descriptions in Your Report
Your report will often describe where in the prostate each core was taken from. Common location terms include:
- Right / Left: Which side of the prostate the core came from.
- Base / Mid / Apex: The top (base), middle, and bottom (apex) of the prostate.
- Peripheral zone: The outer part of the prostate where most cancers originate.
- Transition zone: The inner part of the prostate surrounding the urethra.
Knowing where cancer was found can help your care team plan surgery or radiation more precisely.
Questions to Ask Your Doctor
- How many cores were positive, and from which locations?
- What is my Gleason score and Grade Group?
- Was perineural invasion or cribriform pattern present?
- What is the percent involvement in my positive cores?
- Based on these results, what risk category am I in?
- Do you recommend any additional testing (such as a genomic test or MRI)?
Don't worry if you don't understand every word in your pathology report the first time you read it. Even experienced healthcare professionals review these reports carefully. Highlight unfamiliar terms, write down your questions, and bring a copy of your pathology report to your appointment. Avoid drawing conclusions based on one word or one finding. Your healthcare team will interpret your biopsy results by looking at the complete picture—including your PSA, imaging, physical examination, and pathology report—to recommend the treatment plan that is right for you.