Modification of radiation carcinogenesis by marihuana.
Male, female, and ovariectomized female Sprague-Dawley rats were irradiated with 400 rads, 150 rads, or 300 rads, respectively, of 60Co gamma rays when they were between 40 and 50 days of age. The animals were injected three times weekly with either marihuana extract or with alcohol-emulphor carrier. Comparable unirradiated groups were similarly injected. Mean survival time in males was significantly shorter in the 400 rad + marihuana group compared with the three other groups whose mean survival times did not differ. Through the 546 days that the males were observed, the total number of tumors other than fibrosarcomas was significantly greater following radiation and marihuana (22) than radiation alone (6). Fifteen of the tumors were of breast or endocrine tissues. No differences were seen in the unirradiated groups. In the females, which were observed for 635 days, the total number of breast tumors was greater with the combined treatment (38) compared with radiation alone (22). This was entirely due to a marked difference in the adenocarcinoma incidence, which was 21 (radiation + marihuana) compared with four (radiation alone). The number of adenofibromas was similar in the two groups. In the unirradiated female groups the breast adenocarcinoma incidence was eight in the marihuana group and two in the control group. Ovariectomy resulted in a lower breast tumor incidence in all groups. Nonbreast tumors were more frequent in the ovariectomized-irradiated groups. Radiation plus marihuana produced more nonbreast tumors (25) than radiation alone (17) in the ovariectomized females.
D000230:Adenocarcinoma / Q000453:epidemiology*; D000232:Adenofibroma / Q000453:epidemiology; D000818:Animals; D002369:Castration; D003043:Cocarcinogenesis; D004307:Dose-Response Relationship, Radiation; D013759:Dronabinol / Q000031:analogs & derivatives* / Q000494:pharmacology; D005260:Female; D008297:Male; D008325:Mammary Neoplasms, Experimental / Q000453:epidemiology; D009374:Neoplasms, Experimental / Q000453:epidemiology; D009381:Neoplasms, Radiation-Induced / Q000453:epidemiology*; D051381:Rats
D013759:Dronabinol; C025351:delta(9)-tetrahydrocannabinolic acid