What is the approach for staging prostate adenocarcinoma?

Prostate Adenocarcinoma Staging

Prostate adenocarcinoma staging should utilize the TNM classification system (1997 TNM modified by AJCC criteria), combined with Gleason score and PSA level to stratify patients into risk categories that guide treatment decisions and predict outcomes.

Classification System

Use the 1997 TNM classification modified by American Joint Cancer Committee criteria as the standard staging framework 1. This system stratifies tumors by:

• T category: Method of tumor detection and anatomic extent
• N category: Regional lymph node involvement
• M category: Distant metastases
• Gleason score: Histologic grade
• PSA level: Serum prostate-specific antigen concentration

Initial Diagnostic Workup

Standard Clinical Assessment

Perform digital rectal examination (DRE) and transrectal ultrasound prior to biopsy 1. These establish baseline clinical staging and guide biopsy targeting.

Obtain multi-parametric MRI before prostate biopsy 1. MRI provides superior local staging information compared to DRE, with 51% sensitivity versus 12% for detecting non-organ confined disease 1.

Perform systematic biopsies (minimum six cores) with histopathologic assessment 1. The pathology report must specify:

• Number and location of positive biopsies 1
• Length of biopsy core involvement in millimeters or percentage 1
• Gleason score and ISUP grade group 1
• Presence of extraprostatic extension, lymphovascular invasion, intraductal carcinoma, or invasive cribriform pattern 1

Gleason Scoring Standards

Apply the Gleason grading system as the standard for tumor grading 1:

• Sum the two dominant growth pattern grades
• When three grades present, use the highest grade plus the dominant grade
• Document the proportion of Gleason grades 4 and 5 disease (modified Gleason score) 1

Do not assess tumor grade in patients previously treated with radiotherapy or hormonal therapy 1.

Risk Stratification

Classify localized disease as low-, intermediate-, or high-risk based on clinical stage, PSA, and Gleason score 1:

Low-Risk Disease

• T1-T2, Gleason score ≤6, PSA <10 ng/ml 1
• No additional imaging required beyond initial workup 1

Intermediate-Risk Disease

• Perform cross-sectional abdominopelvic imaging and bone scan for metastatic screening 1
• For ISUP grade group 3 disease, obtain PSMA PET/CT if available to increase staging accuracy 1
• Abdominal/pelvic CT scan indicated for T2a or higher with PSA >15 ng/ml and Gleason score ≥7 1

High-Risk Disease

• Perform metastatic screening using PSMA PET/CT if available, or at minimum CT chest/abdomen/pelvis and bone scan 1
• Renal ultrasound and CT scan mandatory for stage T3 cancer 1

Advanced Staging Assessments

Bone Metastases Evaluation

Obtain bone scan when any of the following present 1:

• Bone pain
• Locally advanced prostatic lesion (≥T3Nx or T1-4N1-3)
• Gleason grade 4 or 5 with PSA ≥10 ng/ml
• PSA ≥10 ng/ml with any Gleason grade 4 or 5 disease

The average risk of bone metastases outside these criteria is only 3.3% in Europe, making routine bone scanning unnecessary for lower-risk patients 1.

Lymph Node Assessment

Perform pelvic lymphadenectomy limited to ilio-obturator regions in patients undergoing radical prostatectomy 1.

Lymphadenectomy may be omitted in patients with all three favorable prognostic factors 1:

• Stage T1 tumor
• Gleason score <6
• PSA <10 ng/ml

Do not perform isolated lymphadenectomy prior to radiotherapy 1. It may be considered only when risk of nodal invasion is high.

Periprostatic Extension Evaluation

Biopsy seminal vesicles or periprostatic tissue when DRE, imaging, or PSA suggest periprostatic involvement 1. Take these biopsies simultaneously with initial prostatic biopsies when suspicion exists.

Perform seminal vesicle biopsies as second-line investigation if biopsies from bases of both prostatic lobes are positive 1.

Consider pelvic or endorectal coil MRI when radical prostatectomy or radiotherapy planned, extraprostatic extension suspected, and results would modify treatment 1.

Pathologic Staging Considerations

Radical Prostatectomy Specimens

Document these histopathologic findings from radical prostatectomy specimens 1:

• Total tumor volume
• Extent of poorly differentiated tumor (Gleason grades 4 and 5)
• Tumor localization (within or outside transition zone)
• Extraprostatic extension
• Seminal vesicle invasion
• Surgical margin status
• Nodal status

These factors independently correlate with prognosis and PSA recurrence risk at 5 years 1.

Stage T1a/T1b Classification

Classify cancer as stage T1a when it accounts for <5% of resected tissue with Gleason score <7 1. This applies to tissue obtained by transurethral or simple prostatectomy.

Critical Staging Pitfalls

Clinical staging significantly understages disease in up to 59% of cases compared to pathologic examination 2. This limitation creates uncertainty about comparative treatment efficacy and expected outcomes.

MRI-targeted biopsy detects higher-grade cancer more sensitively than systematic biopsy, causing potential grade shift 1. ISUP grade group 2 cancers detected by MRI-targeted biopsy have better prognosis on average than those detected by systematic biopsy alone.

Avoid relying solely on lymph node size criteria on CT/MRI 1. Nodes >8mm short axis in pelvis or >10mm outside pelvis are suspicious, but sensitivity remains below 40% 1.

Stratify patients preoperatively by PSA concentration, ratio of positive to total biopsies, and percentage of grade 4/5 disease 1. This enables proper treatment response evaluation.