Distinct angiogenic and non-angiogenic growth patterns of lung metastases from renal cell carcinoma

We have recently evaluated a classification of non-small-cell lung cancer based upon the presence of an angiogenic or a non-angiogenic growth pattern. The aim of the present study was to test the hypothesis that lung metastases of clear cell renal cell carcinoma (RCC) can grow without eliciting angiogenesis and give rise to the same set of growth patterns.

Tissue sections of 24 patients with lung metastases from clear cell RCC were analysed. Haematoxylin and eosin and reticulin staining were performed to evaluate growth pattern. Double-labelling with antibodies to CD34 and proliferating cell nuclear antigen (PCNA) was performed to determine the endothelial cell proliferation fraction (ECPF) and the microvessel density (MVD). Three growth patterns were observed. In the destructive growth pattern (54%), the architecture of the lung was not preserved. In the alveolar (33%) and interstitial growth patterns (13%), the normal lung parenchyma was preserved within the metastases. MVD was higher in the destructive than in the alveolar growth pattern (P = 0.009). ECPF was higher in the destructive (mean 31.1 +/- 22.7%, median 30.0) than in the alveolar growth pattern (mean 3.6 +/- 2.8%, median 3.2; P = 0.005).

The present study demonstrates that highly angiogenic primary tumours can give rise to non-angiogenic metastases. This type of metastasis may be resistant to antiangiogenic therapy.