Production of metastases by treatment with carcinostatic agents. I. Effects of carcinostatic agents on the host.

The number of lung "metastases" that develop from intravenously injected tumor cells is modified by the administration of certain carcinostatic agents. The number is increased by post-treatment with small amounts of mechlorethamine (HN~) or actinomycin D, but is decreased by larger amounts. Pretreatment with HN~ results in increased numbers of lung metastases. Pretreatment with actinomycin D, HN~, or triethylenemelamine (TEM) results in a strikingly increased growth of transplanted ascites tumor cells. Increasing the dose of actinomycin D or HNr reduces the minimum number of cells required for successful transplantation. Although experimental results like these cannot be directly applied to clinical work, they still serve as a warning that cancer chemotherapy that is inadequate because the dosage is insufficient or the drug is ineffective may sometimes be even less satisfactory than no chemotherapy at all.