Growth patterns of pulmonary metastases and primary tumours from five murine fibrosarcoma cell clones

The growth patterns, including the size, shape and regional preferences, of lung metastases from five murine fibrosarcoma cell clones were studied. Spontaneous metastases developed from tumours formed by subcutaneous inoculation of the cell clones. Lung colonies (experimental metastases) were established by i.v. injection of cells. The numbers of both spontaneously and experimentally formed subpleural lung metastases were counted through a stereomicroscope. The fraction of colonies that was located subpleurally was determined in histological sections of lungs. The growth kinetics of clonally derived primary tumours, and the number of spontaneous and experimental lung metastases, differed greatly between certain cell clones. The number of spontaneous lung metastases was correlated with the maximum size of primary tumours. No close correlation was observed between the size of the primary tumours and the size of experimental metastases. There were differences between the cell clones in the shape and regional preferences of their lung deposits. The subpleural colonies were generally larger than the intrapulmonary ones. Thus, both the regional distribution and the growth pattern of lung deposits differed between the clones.