Surgery for lung mets (metastases)

• development of distant metastases is one of the primary characteristics of malignant tumours
• lung metastasectomy has been progressively accepted as a therapeutic option in oncology patients - the objective of this procedure is to remove the metastases while conserving as much as possible of the lung
• most lesions that spread to the lung are relatively insensitive to the currently available chemotherapy
• majority of pulmonary metastases do not cause any symptoms and are detected incidentally on radiographic studies or are detected on routine follow-up chest X-ray
  • symptoms occur in up to 20% of patient and depend on the proximity of the mestastatic lesion to the central airways
• criteria have been proposed to identify and select patients who will benefit optimally from resection of their pulmonary metastases (1)
  • primary tumour site must be controlled or immediately controllable
  • extrapulmonary metastases must be excluded - if there are extrapulmonary deposits then they should be controlled before the surgical procedure in the lung
  • all pulmonary lesions must be resectable - this is to ensure complete control of the disease
  • patient must be able to tolerate the degree of envisaged surgical treatment
• video-assisted thoracoscopic surgery (VATS) using high-resolution video imaging can be helpful for diagnosis, staging and resection of thoracic tumours, but the possibility of its utilization is highly limited as metastases can be found on the surface of the lung or the outer 10–20% (with high dependence on the size of the lesion)
  • metastases within the lung parenchyma may be undetectable by VATS
  • complete resection is the major prognostic factor for good long-term results - however complete resection is not guaranteed with the VATS procedure
  • VATS should be advocated only for staging metastases extension or their diagnosis - however VATS cannot be considered the standard approach for resection (1)
• more than half of patients who undergo therapeutic pulmonary metastasectomy will experience recurrence - usually within the same lobe (2)
• in consideration of various the use of pulmonary metastectomy of various pulmonary metastatic tumours - primary tumours included epithelial and germ cell tumours, sarcoma and melanoma
  • survival after complete metastasectomy was (2):
    • at 5 years 36%
    • at 10 years 26%
    • these figures compared with survival figures related to incomplete resection of:
      • at 5 years 13%
      • at 10 years 7%
    • therefore....patients who undergo pulmonary metastasectomy have a more than 3-fold increased chance of 10-year survival compared with those who undergo incomplete resection of the lung
• prognostic factors
  • complete resection of the disease is the most important factor influencing long-term prognosis
  • number of resected pulmonary deposits - solitary metastases had significantly better long-term survival than those affected by multiple ones
  • disease-free interval - this is another factor reported to affect long-term prognosis
  • histology subtype and differentiation grading as prognostic factors are often also cited as prognostic factors

Reference:

1. Rena O et al. Pulmonary metastases from epithelial tumours: late results of surgical treatment. Eur J Cardiothorac Surg. 2006 Aug;30(2):217-2
2. GP magazine (4/5/07):40-41.