Metastasis is the major obstacle in cancer therapy. Lung cancer is divided into 
4 histological groups, such as small cell carcinoma, squamous cell carcinoma, 
adenocarcinoma and large cell carcinoma, representing different clinical 
behaviors. Novel metastasis models of human lung cancer cells to the liver, 
kidneys and lymph nodes were established in SCID mice depleted of NK cells. In 
the model under study, small-cell carcinoma cells mainly formed lymph-node 
metastases, while squamous cell carcinoma cells mainly metastasized to the liver 
and kidneys. Moreover, adenocarcinoma cells formed lung metastases and malignant 
pleural effusion. These findings suggest that our model reflects clinical 
behavior of metastatic lung cancer and is useful for evaluation of 
antimetastatic modalities.