## Distinguishing Localised from Metastatic Prostate Cancer ### Key Diagnostic Features **Key Point:** The presence or absence of distant metastases is the fundamental distinction between localised and metastatic disease. Skeletal scintigraphy (bone scan) or modern imaging (CT/MRI) demonstrating absence of bone metastases is the defining feature of localised prostate cancer. ### Feature Comparison Table | Feature | Localised PCa | Metastatic PCa | |---------|---------------|----------------| | **Bone metastases** | Absent | Present (85% of mets) | | **PSA level** | Variable (can be high) | Usually very high (>100) | | **Gleason score** | Can be ≤6 or >6 | Often >6, but not always | | **DRE findings** | Hard nodule/induration | Hard nodule/induration | | **Staging** | T1–T4, N0, M0 | Any T, Any N, M1 | ### Why Other Options Are Not Discriminators **High-Yield:** PSA elevation occurs in both localised and metastatic disease—it is not a discriminator. A patient with localised T3 disease can have PSA >100 ng/mL, while a patient with metastatic disease may have PSA in the 50–80 range. Similarly, Gleason score and DRE findings are not specific to either stage. **Clinical Pearl:** Bone is the most common site of metastasis in prostate cancer (85% of metastatic cases). Absence of skeletal involvement on imaging is the gold standard for confirming localised disease and is essential for staging and treatment planning. ### Staging Reminder TNM staging for prostate cancer: - **M0** = No distant metastases → Localised disease - **M1** = Distant metastases present → Metastatic disease Imaging modality choice depends on risk: bone scan, CT, or MRI for staging high-risk localised or suspected metastatic disease [cite:Harrison 21e Ch 97].
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