Introduction: Non-small cell lung cancer has a poor prognosis, including those with operable, apparently localised, disease. Preoperative staging investigations and histo-pathological analysis are poor at detecting small clusters of tumour cells, particularly in lymph nodes.
State of the art: New methods based on immunohistochemistry, or molecular biology, have been developed to detect these so-called micro-metastases. We present a ten-year review of the literature published on this topic.
Perspective: These publications primarily reported on the detection of micro-metastases within mediastinal lymph nodes removed at operation in order to identify patients at risk of recurrence, for whom adjuvant therapy might be offered.
Conclusions: Lymph node micro-metastases have been demonstrated to be an independent prognostic factor for survival, especially in stage I patients. On the other hand, the presence of bone marrow micro-metastases did not appear to be of significant prognostic value in non-small-cell lung cancer. Finally, the clinical relevance of circulating tumour cells is still debatable, although recent published studies show interesting results.