INFLUENCE OF NITROGEN MUSTARD UPON ESTABLISHMENT OF LUNG METASTASES FOLLOWING INJECTION OF INTRAVENOUS AUTOLOGOUS CELLS IN BENZO(A)PYRENE-INDUCED RAT FIBROSARCOMA

When rats bearing a chemically induced tumour were treated with methyldi (β‐chloroethyl) amine hydrochloride (HN2), a higher percentage developed lung “metastases” than in a series of untreated controls. Because the primary benzo (a)‐pyrene‐induced fibrosarcoma does not metastasize spontaneously, lung “metastases” were induced by removing all but 250 mg of the primary tumour and re‐injecting an estimated 106 live cells intravenously. Macroscopic and/or microscopic lung metastases were identified in 23% (7/31) of the control animals at the time the experiment was terminated (day 36). The incidence of rats with lung metastases was increased to 79% (23/29) if the rats were treated with HN2. The HN2 was given at the maximum tolerated dose on days 0, 3, 6, 12, 15 and 18 and the cells prepared from the primary tumour and re‐injected on day 9. HN2 produced a gradual fall in the peripheral lymphocytes, reaching 37% of the initial value by day 18. The possible relationship between the HN2‐induced fall in peripheral lymphocytes and the increased incidence of lung metastases is discussed. Copyright © 1968 Wiley‐Liss, Inc., A Wiley Company