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Pulmonary Metastases

Pulmonary Metastases

1. Pathogenesis

A. The lung is the first capillary bed draining most primary sites, with tumor cells usually depositing in the periphery
B. 10-20% of patients with pulmonary metastases have disease confined to the lungs (especially with sarcomas)

2. Diagnosis

A. CT scanning is sensitive but not specific, and may underestimate the number of malignant nodules
B. Needle biopsy rarely adds additional information
C. Sarcomas and melanomas are the most likely to cause a solitary metastasis

3. Patient Selection

A. There are four criteria which should be met prior to resection of pulmonary metastases:
1) Resection should only be performed if removal of all disease is possible
2) The patient must have adequate pulmonary reserve to tolerate resection
3) Local control of the primary tumor
4) Absence of metastases elsewhere in the patient
5) Prognostic Factors
a) Histologic cell type affects the pattern of metastasis as well as outcome
b) Tumors with longer doubling time have better survival
c) The number of metastases, the disease-free interval, and unilateral vs. bilateral disease are not prognostically significant
d) Complete resectability is the most important indicator of improved survival

5. Operative Technique

A. Wedge resections should be performed wherever possible to preserve parenchymal tissue
B. Manual exploration is preferred to thoracoscopic examination to identify all nodules
C. Bilateral disease may be treated either by staged bilateral thoracotomy or median sternotomy for a single operation

6. Results

A. Outcomes vary according to primary tumor type
Tumor type5-year survival
Soft tissue sarcoma25%
Osteogenic sarcoma20-40%
Colon/rectal carcinoma8-37%
Renal cell carcinoma13-50%
Breast carcinoma14-49%
Head/neck carcinoma45-50%
Melanoma25%

7. Pancoast Tumor (Superior Sulcus Tumor)

A. Primary lung cancer which arises from the apex of the lung
B. Structures susceptible to invasion include pleura, brachial plexus, sympathetic chain, ribs, and vertebra
C. The Pancoast syndrome, or superior sulcus tumor syndrome, is characterized by ipsilateral shoulder/arm pain
D. Horner's syndrome (ipsilateral anhidrosis, ptosis, enopthalmus) develops with invasion of sympathetic nerves

8. Treatment of Pancoast Tumor

A. Preoperative radiation therapy followed by operative resection 4 weeks later (Paulson protocol)
B. Contraindications include extensive involvement of the brachial plexus, subclavian artery, or vertebrae; SVC or recurrent laryngeal nerve involvement; distant metastasis; and mediastinal node involvement (relative)