Metastatic Adenocarcinoma

Metastatic adenocarcinoma arises when glandular cancers spread to distant organs via blood or lymphatics. ⚠️ They account for a large proportion of metastatic tumours, complicating treatment and prognosis. Early detection is critical.

🔎 Common Primary Sources

• 🫁 Lung: Spreads to liver, bones, brain, adrenals.
• 🦴 Thyroid: Papillary/follicular → lungs, bones.
• 🍽️ Gut: Oesophagus (Barrett’s), stomach, colorectal → liver, peritoneum.
• 👩‍🦰 Ovarian/Uterine: Spread to peritoneum, lungs, liver, nodes.
• 🩺 Pancreas: Aggressive, late presentation → liver, peritoneum.
• 🎗️ Breast: Ductal/lobular → bone, liver, lungs, brain.
• 🧾 Adrenal/Parathyroid: Rare but can metastasize widely.
• 🩸 Renal cell carcinoma: (not classic adenocarcinoma but similar spread) → lungs, bones, liver, brain.

🚫 Common Cancers Not Typically Adenocarcinoma

• Bladder: Transitional cell carcinoma (TCC). Rare adenocarcinoma subtype exists.
• Larynx: Squamous cell carcinoma (SCC), smoking/alcohol related.
• Cervix: Mostly SCC (HPV-linked), though adenocarcinoma occurs in some cases.

🧪 Diagnostic Approach

• Biopsy & Histopathology: Gold standard, IHC to suggest tissue of origin.
• Imaging: CT, MRI, PET for mapping spread.
• Blood Markers: e.g., CA-125 (ovarian), CEA (colorectal), PSA (prostate differential).

💊 Treatment Options

• 🔪 Surgery: Occasionally for isolated/oligometastatic disease.
• 💉 Chemotherapy: Systemic therapy is cornerstone for widespread disease.
• 🎯 Targeted Therapy: EGFR, ALK, HER2, KRAS inhibitors depending on mutation profile.
• ☢️ Radiotherapy: Local control & symptom palliation (e.g., bone/brain mets).
• 🛡️ Immunotherapy: Checkpoint inhibitors (e.g., PD-1/PD-L1 blockade) increasingly used in lung, GI, and renal adenocarcinomas.

📚 Clinical Pearls

• 🧬 Always consider adenocarcinoma of unknown primary (CUP) when biopsy shows glandular histology but no clear source.
• 💡 Lung, colorectal, pancreas, and breast are the most frequent culprits in adults.
• ⚠️ Paraneoplastic syndromes may provide diagnostic clues (e.g., hypercoagulability in pancreatic adenocarcinoma).
• 🧾 Prognosis depends on primary site, burden of metastases, and available targeted therapies.

Cases — Metastatic Adenocarcinoma

• Case 1 — Pulmonary metastasis 🌬️: A 62-year-old woman with history of colonic adenocarcinoma (resected 2 years ago) presents with cough and dyspnoea. CXR: multiple “cannonball” pulmonary metastases. Biopsy confirms metastatic adenocarcinoma of colonic origin. Managed with systemic chemotherapy and palliative care.
• Case 2 — Hepatic metastasis 🍷: A 58-year-old man presents with weight loss, right upper quadrant discomfort, and hepatomegaly. History: pancreatic adenocarcinoma diagnosed 6 months earlier. CT: multiple hypodense lesions in the liver. Diagnosis: hepatic metastases from pancreatic adenocarcinoma. Managed with palliative chemotherapy (gemcitabine-based) and supportive care.
• Case 3 — Brain metastasis 🧠: A 54-year-old woman with known metastatic lung adenocarcinoma presents with new seizures and headache. MRI brain: solitary enhancing lesion in the parietal lobe with surrounding oedema. Diagnosis: brain metastasis from lung adenocarcinoma. Managed with high-dose dexamethasone, anti-epileptics, and stereotactic radiosurgery.
• Case 4 — Bone metastasis 🦴: A 66-year-old man with prostate adenocarcinoma presents with back pain and weakness in his legs. MRI spine: vertebral metastases causing spinal cord compression. Diagnosis: spinal cord compression due to metastatic prostate adenocarcinoma. Managed with urgent IV steroids, radiotherapy, and androgen deprivation therapy.
• Case 5 — Peritoneal carcinomatosis ⚠️: A 50-year-old woman presents with abdominal distension, ascites, and weight loss. Paracentesis: malignant cells consistent with ovarian adenocarcinoma. Diagnosis: peritoneal metastases (carcinomatosis) from ovarian adenocarcinoma. Managed with cytoreductive surgery, platinum-based chemotherapy, and palliative symptom control.

Teaching Point 🩺: Adenocarcinoma is the most common epithelial cancer type and frequently metastasises to liver, lung, bone, brain, and peritoneum. Symptoms depend on site: cough/dyspnoea (lung), RUQ pain/jaundice (liver), seizures (brain), bone pain/fractures (bone), ascites (peritoneum). Diagnosis: imaging + biopsy to confirm metastatic origin. Management: usually systemic therapy (chemo, hormonal, immunotherapy) and palliative measures. Curative surgery rarely possible unless solitary metastasis.