Inhibition or Enhancement by 4 Pacific Island Food Plants Against Cancers Induced by 2 Amino–3-Methylimidazo[4,5-f]Quinoline in Male Fischer 344 Rats

Abstract

A 1-yr carcinogenicity bioassay was conducted in rats fed 2-amino-3-methylimidazo[4,5-f]quinoline (IQ), simultaneously with AIN-76/ high-fat (HF) diet alone, or with 10% starch replaced with kumara, pineapple, coconut, or taro, prepared as for a human diet. All of the non-IQ treated control, kumara, pineapple, or taro but not coconut-fed rats survived to 1 yr. None of the IQ-fed animals survived to 1 yr and although there were minor survival time differences among the groups, none was statistically significant. At sacrifice, IQ/HF controls had tumors in the skin, Zymbal's gland, ear canal, oral cavity, liver, and small intestine, totaling 32 among 20 animals. Kumara-fed rats had a similar tumor distribution but no tumors in the ear or oral cavity, and a total of 27 tumors among 20 animals, whereas pineapple-fed rats showed a somewhat lower tumor incidence (23/20 animals), including no small intestine lesions. Unexpectedly, a higher tumor incidence, especially of skin tumors, was seen in coconut and taro-fed animals (35/20 and 41/20 animals, respectively). In particular, the incidence of malignant liver tumors and gastrointestinal tumors were significantly increased in the taro-fed group in comparison with the kumara group.

ACKNOWLEDGMENTS

We are grateful to the New Zealand Lotteries Board and the Auckland Division, Cancer Society of New Zealand, for financial support of this work. We are also grateful to Tracey Booten, Marlene Goedhart, Christine Ford, and Kirsten Wrabetz for technical assistance.