M1: Evaluation for Metastases

Less than 50% of patients undergoing curative resection for bronchogenic carcinoma survive 5 years. Most deaths are due to local recurrence or disseminated disease. Analyses of the causes of death within a year of surgery suggest that a third of patients have metastases. Likely sites of metastases include bone, brain, liver, and adrenal glands.

The probability of metastases depends on the TNM stage and the histologic type. The higher the stage the more frequent the metastases. For example, there is a 12 fold increase in cerebral metastses in patients with T2N1 tumors compared to T1N0.

The frequency of metastases are less for squamous cell carcinomas than the adenocarcinomas. In resected patients with Stage I cancers, metastases occurred in 15% with squamous cell carcinoma vs 27% with adenocarcinomas.

Hillers et al performed a literature review (1966-91) to determine the proportion of patients with potentially operable non-small cell lung cancer that could be spared thoracotomy by a search for extrathoracic metastases. Although only 17 studies were suitable for analysis the frequency of metastases were (95% confidence interval)

• Head CT 3.3% (2.1 - 4.4%)
• CT adrenal 4.7% (3.0 - 6.4%)
  
• Bone scan 9.3% (6.7 - 12%)
• Liver Imaging 2.3% (0.9 - 3.3%)