The Effect of 1:2:5:6-Dibenzanthracene on the Growth of Brown-Pearce Rabbit Carcinoma

Abstract

The effects of the carcinogenic hydrocarbons on spontaneous and transplantable tumors of lower animals have been investigated on several occasions but the results have been somewhat contradictory. Inasmuch as these coal-tar derivatives are known to produce hyperplasia of normal tissues, they might be expected to cause increased proliferation of neoplastic tissues. Thus Rous and Kidd (1) have shown that the virus of the Shope rabbit papilloma is able to produce a fulminating carcinomatosis when combined with applications of a coal-tar derivative of low-grade carcinogenic potency. Such carcinomatosis could not be produced as a result of mere tarring or by the implantation of the virus without the application of the coal tar. Andrewes, Ahlstrom, Foulds and Gye (2) found that when the virus of the infectious fibroma of rabbits is injected into tarred animals there occurs a generalized fibromatosis which is not found in rabbits without tar. On the other hand Haddow (3) succeeded in producing marked inhibition of the growth of the Jensen rat sarcoma by intraperitoneal injections of various coal-tar derivatives. Pybus and Miller (4) and Pollia (5) obtained similar but somewhat less striking results with spontaneous mouse tumors. In view of the discrepancy in these results it was thought advisable to investigate the effects of 1:2:5:6-dibenzanthracene on the Brown-Pearce rabbit tumor. The latter is a readily transplantable, highly malignant carcinoma of the testis which was first described by Brown and Pearce in 1923 (6). The tumor metastasizes and kills the animal in a high proportion of cases, and, as a test object, seems much more satisfactory than most other transplantable animal tumors. In only a small proportion of cases the tumor may undergo spontaneous regression.