Lung cancer model for studying multi-step metastasis.

The sequence of the spread of cancer has been a problem for over a century. A simple model based on lung cancer is proposed. It utilizes three well known facts: that lung cancer may selectively attack the adrenals, that such adrenal deposits may or may not invade the outflow venous tract and that contralateral lung deposits are uncommon in this cancer. Therefore any sequence of spread from the ipsilateral lung to the adrenal glands and thence to the contralateral lung merits attention. Its study might throw light on the laws governing multi-step metastasis in man.