By surgically removing the primary tumor at different intervals after its inoculation and determining 45 days later the incidence of lung metastases in the operated mice, the following results were obtained:

  1. The incidence of lung metastases was related to the size of the primary tumor at the time of its removal. The larger the tumor when removed, the higher the incidence of lung metastases found.

  2. Fast-growing tumors produced metastases earlier than slow-growing ones, in spite of the fact that the latter stayed longer in the host than the fast-growing tumors.


Aided by grants from the Minnesota Division of the American Cancer Society and the United States Public Health Service.

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