Abstract
Summary
1. If a subcutaneously implanted Yoshida sarcoma is sensitive to nitrogen mustard N-oxide (“NMO”), pre-treatment or short-time post-treatment with NMO produces remarkable metastases. The severity of these metastases following pre-treatment with NMO suggests a strong effect on the host. 2. Treatment of NMO-resistant tumors with NMO does not promote the development of metastases, even with pre-treatment or short-time post-treatment. This indicates that NMO-resistant tumors do not liberate cells to form metastases even when the host is under the influence of NMO. 3. Treatment of tumors with X rays produces essentially the same results as treatment of NMO-sensitive tumors with NMO does. In both instances, diminution of host resistance appears to be an important factor in promoting the development of metastases. 4. Pre-treatment of tumors with cortisone promotes the development of metastases; post-treatment, whether short-time or extended, has no such effect. Evidently the chief action of cortisone is on the host, increasing the ease with which metastases are formed. 5. Post-treatment with either NMO or X rays for an extended period inhibits the formation of metastases, and causes the tumor itself to regress. This observation suggests that carcinostatic agents should be used clinically only in large enough doses.
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