Lymphangiogenesis may explain adrenal selectivity in lung cancer metastases.

The 'seed and soil' hypothesis of organ selectivity in cancer metastasis dated back to the 1870s. A century later, a review of significant selectivity data revealed that the adrenals featured in 11 of 12 classes of it, thus promoting these two organs for research. Fortunately, two discoveries have also occurred, namely, (a) that cancer stimulates lymph vessel formation, i.e., lymphangiogenesis, and (b) that lymph and blood vessels are differentially stainable. Accordingly, these interesting ideas should be exploited with a hypothesis. Therefore, it is proposed that, at autopsy in lung cancer cases, the tissues between the primary lung tumor and the adrenal secondary should be meticulously serially sectioned and disjunctively stained because they must reveal what naturally occurs in this zone during life. It is predicted that this maneuver will identify lymphangiogenesis as the phenomenon responsible for the age-old puzzle of adrenal selectivity. Indeed, it may explain other puzzles such as intracranial lymphatic connectivity. Copyright 2010 Elsevier Ltd. All rights reserved.