Related Subjects:
|Cancer of Unknown Primary
|Palliation prescribing
|Levomepromazine
|Analgesia and Pain management
|Sedation and Analgesia on ITU
|Neuropathic Pain Management
|Codeine
|Dihydrocodeine
|Diamorphine
|Morphine
|Paracetamol (Acetaminophen)
❓ Cancer of Unknown Primary (CUP) – a diagnosis where malignant cells are identified but the primary tumour site cannot be found.
🔍 In some patients, the primary lesion is never discovered despite extensive investigations.
📘 About
- Uncommon diagnosis, accounts for ~3–5% of all cancers.
- Primary tumour may be too small, destroyed by immune response, or removed during previous surgery.
⚙️ Aetiology
- Primary cancer may be very small and slow-growing.
- The immune system may have eradicated the original lesion.
- The primary tumour may have been excised incidentally during earlier surgery.
🧪 Cytology
- 🟨 Squamous cell carcinoma (~5%).
- 🟦 Undifferentiated carcinoma / neuroendocrine tumour (~30%).
- 🟥 Adenocarcinoma / poorly differentiated carcinoma (~65%).
🔍 Clinical Features
- Common metastatic sites: 🫁 chest, 🥼 adrenals, 🦴 bone, 🧠 brain.
- Ask about bowel and upper GI symptoms (colorectal, gastric origin).
- Full skin check 🩺 to rule out melanoma.
🧫 Pathology
- Excisional biopsy: Entire lump removed.
- Incisional biopsy: Portion of lump/tissue removed.
- Core biopsy (preferred): Tissue cylinder removed via wide needle.
- FNA: Cells/fluid aspirated via fine needle.
🧭 Investigations – “Hunting the Primary”
- 🧪 Bloods: FBC, U&E, LFTs, TFTs, PSA, directed tumour markers.
- 🖥️ CT chest/abdomen/pelvis with contrast.
- 🦴 Bone scan if symptoms suggest skeletal spread.
- 🧲 MRI chest/abdomen/pelvis (second-line for clarification).
- 🔥 PET-CT for metabolically active disease.
- 👩 Mammogram in women.
- 📹 Endoscopy (upper GI, colonoscopy) if symptoms or suspicion.
- 🎯 Directed tumour markers (CA-125, CgA, AFP, β-hCG, PSA).
- Core biopsy of most accessible lesion for histology & molecular analysis.
🧬 Immunohistochemistry (IHC) Panels – Common Markers
- 🩷 Breast: ER, GCDFP-15, mammaglobin, HER-2, GATA-3.
- 🫁 Lung: TTF-1, surfactant protein A, napsin A.
- 🧔 Prostate: PSA, PAP, AMACR.
- 🧬 Lymphoma: LCA, CD3, CD20, CD45, PAX5, Bcl-2, cyclin D1.
- 👩🦰 Ovarian/Müllerian: ER, WT-1, PAX8.
- 💪 Sarcoma: Desmin, CD31, SMA, MyoD1, myogenin.
- 🧠 Neuroendocrine: Chromogranin, synaptophysin, CD56.
- 🍼 Germ Cell: β-hCG, AFP, OCT3/4, CD30.
- 💧 Urothelial: CK7, CK20, GATA-3.
- 🍽️ Colorectal: CK7, CK20, CDX2, SATB2, CEA.
- 🩺 Renal: RCC, CD10, PAX8.
- 🧪 Hepatocellular: HepPar-1, Glypican-3, Arginase-1.
- ⚫ Melanoma: S100, HMB-45, SOX10.
- 🦋 Thyroid: Thyroglobulin, TTF-1, PAX8.
🩺 Management
- Multidisciplinary care via Oncology MDT is essential.
- Palliative chemotherapy may be considered in selected cases (e.g. responsive histologies).
- Supportive care – analgesia, symptom control, palliative services – is crucial for QoL.
📖 References
