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Oncology-Surgical Oncology: Metastatic Disease - Study Guide
I. Surgery for Metastatic Disease: General Principles
I. Surgery for Metastatic Disease: General Principles
- Resection of Metastases: Resection of single (and occasionally multiple) metastatic sites is considered in carefully selected patients. Key factors include the primary tumor's location and the location of the metastases. Common sites for resection include lungs, liver, and brain. Multidisciplinary team (MDT) discussion is crucial. Prolonged survival is possible but not guaranteed.
- Curative Potential: In some cancers, lymphatic clearance can be curative.
- Adjuvant Therapy Avoidance: It may eliminate the need for adjuvant chemotherapy or radiotherapy (e.g., axillary radiotherapy in breast cancer).
- Indications: Breast, colorectal, head and neck, and penile cancers.
- Contraindications: No role in prophylactic nodal dissection for melanoma.
- Sentinel Node Dissection: Has a role in breast and melanoma cancers; shown to be beneficial in breast cancer (ALMANAC trial, 2004). Now a standard practice in UK and US.
- Spread: Primarily hematogenous, usually via the portal venous system.
- Detection: Often incidental findings on post-operative surveillance CT scans. Further investigations include MRI and CT-PET (to rule out extra-hepatic spread).
- Most Experience: With colorectal cancer metastases.
- Resection: No randomized trials support liver resection, but contemporary series show 5-year survival up to 75% in selected patients (colorectal origin) with low operative mortality (<1%) but significant morbidity (30%).< />pan>
- Neoadjuvant Chemotherapy: Increases resectability rates and improves post-resection survival by downsizing metastases.
- Fong Score: Predicts prognosis. Points are assigned for: tumor size >5cm; node-positive primary tumor; >1 tumor; disease-free interval <12 months; cea>200ng/mL. Higher scores indicate worse prognosis.
- Repeated Resection: Possible (including laparoscopic approaches) with outcomes comparable to initial resection if selection criteria are met.
- Staged Resection: Possible using portal vein embolization to encourage remnant liver hypertrophy.
- Non-Colorectal Cancers: Benefit is variable; better outcomes reported for neuroendocrine (up to 50% 5-year survival) and genitourinary (up to 60% 5-year survival) cancers. Limited or no benefit for breast and melanoma metastases except in highly selected patients.
- Laparoscopic Resection: Increasingly used, reducing post-operative stay and recovery time.
- Other Treatment Options: Radiofrequency ablation (RFA), microwave ablation (newer, potential advantages over RFA), alcohol injection, and cryotherapy (less common, still used for HCC).
- Spread: Lymphatic or hematogenous.
- Second Most Common Site: One-fifth of patients present with lung metastases as the sole site.
- Detection: Often incidental findings on post-operative surveillance CT scans; CT-PET used to exclude extra-thoracic disease.
- Resection Criteria: Controlled primary tumor, medically fit patient, limited lung metastases (some centers now accepting patients with lung and liver metastases from colorectal cancer for sequential resections).
- Metastasectomy: Low morbidity and mortality; can be performed repeatedly.
- Thoracoscopic Techniques: Commonplace.
- 5-Year Survival: Varies significantly by primary tumor origin (e.g., osteosarcoma 40%; colorectal 35%; melanoma 20%; germ cell tumors 86%).
- Presentation: Often pathological fracture.
- Common Primary Sites: Breast, prostate, lung, thyroid, and kidney cancers.
- Survival: Highly variable, from 3 months (lung cancer metastases) to over 4 years (breast cancer metastases).
- Investigations: MRI and CT-PET are most accurate, followed by bone scanning.
- Internal Fixation: Indicated for weight-bearing bones (especially lesions >2.5cm or involving circumference), painful lesions after radiotherapy, improved mobilization/nursing care, and good bone quality.
- Spinal Metastases: Requires stabilization to prevent cord compression.
- Treatment Options: Internal fixation (plates, intramedullary nails, prosthetic replacement); external fixation (for extensive disease); amputation (rare, for fungating tumors, recurrent infections, intractable pain); percutaneous bone cement injection (minimally invasive, for selected cases like spinal metastases).
- Common: Up to 10% of cancer patients develop brain metastases. Incidence varies by primary tumor (lung cancer highest, colorectal lowest).
- Spread: Hematogenous; distribution reflects blood flow (cerebrum > cerebellum > brainstem).
- Presentation: Headache, focal weakness, altered mental status, epilepsy, and hemorrhage (acute neurological state).
- Diagnosis: MRI (detects smaller metastases than CT).
- Survival: Without therapy: 2 months; with steroids: 3 months; with radiotherapy: 6 months.
- Surgery: Indicated for diagnosis confirmation, pressure relief, local control improvement, and survival improvement in selected cases.
- Poor Prognostic Indicators: Uncontrolled systemic disease, poor general health, infratentorial location, poor neurological status, short interval between primary and metastatic diagnoses.
- Resection: Usually limited to single metastases in accessible locations; resection of multiple metastases may be considered in some cases. Prolonged survival possible (duration varies by primary tumor).
- Surgical Intervention: Rarely indicated; usually managed medically.
- Thoracoscopy: Occasional role for drainage, adhesion lysis, pleural biopsy, and instillation of sclerosing agents (talc or bleomycin).
- Pleurectomy: Rarely performed (malignant mesothelioma); high morbidity and mortality (10%), only for very selected patients.
- Pericardial Window: In selected patients, a pericardial window is comparable to percutaneous drainage.
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