Toshiyuki Minoura

Dietary Polyunsaturated Fatty Acids and Cancer: Epidemiological and Experimental Studies

The dietary habits and lifestyle in Japan have changed markedly, and the Japanese diet and incidence of nutritionally-related diseases are rapidly approaching those in Western countries. The intake of dietary polyunsaturated fatty acids (PUFA) in Japan and the USA is similar; the predominant PUFA is linoleic acid (18:2 ω6), contributing approximately 87% of the mean total PUFA intake in the USA and 78% in Japan. The ratio of ω6 to ω3 fatty acids is 4.2 in Japan and 7.5 in the USA. Considering the change in dietary patterns and incidence of nutritionally related cancers in Japan, we examined the effects of ω3 PUFA (eicosapentaenoic acid, EPA) and ω6 PUFA (linoleic acid) on azoxymethane-induced colon carcinogenesis and N-nitroso-N-methylurea (NMU)-induced mammary carcinogenesis in rats. The tumor incidence and tumor yields in both the colon and the breast were significantly lower in rats on the EPA diet than in those on the linoleic acid diet. The balance of PUFA in the diet may influence the mortality rates from colon and breast cancer. Further research is needed to define the optimal level and balance of PUFA in the diet of humans to promote health and prevent disease.

A Case Report of Parapapillary Choledochoduodenal Fistula Associated with Ampullary Carcinoma.

十二指腸乳頭部癌に傍乳頭総胆管十二指腸瘻を併存した症例報告はきわめてまれである.われわれは, 十二指腸乳頭部癌により傍乳頭総胆管十二指腸瘻を形成したと思われた症例を経験したので報告する.患者は72歳, 女性で全身倦怠感を主訴として来院した.十二指腸内視鏡および内視鏡的逆行性胆管膵管造影により, 傍乳頭部総胆管十二指腸瘻併存乳頭癌の診断にて膵頭十二指腸切除術を施行した.内胆汁瘻の成因としての胆石症例の報告は多数みられるが, 本症のごとく, 乳頭部癌が共通管, 総胆管下部および乳頭部粘膜下より十二指腸壁へと浸潤し, 腫瘍組織の崩壊, 脱落による抵抗減弱部が胆汁流出路として形成されると推測される報告は少なく, 本邦報告例は8例であり, これらにおける瘻孔形成機転など検討を加え報告する.

Inhibitory Effect of Eicosapentaenoic Acid on Colon Carcinogenesis

The effect of purified eicosapentaenoic acid (EPA, n-3 polyunsaturated fatty acid) on azoxymethane(AOM)-induced colon carcinogenesis, the alteration of fatty acid composition, and prostaglandin E2 in colon tumors and normal colon mucosa were studied, in comparison to linoleic acid(n-6 polyunsaturated fatty acid). The tumor incidence and tumor multiplicity(tumors per rat) in the colon were significantly lower in rats on an EPA diet than in those on a linoleic acid diet. The results suggest that EPA has an inhibitory effect on colon carcinogenesis by modulating prostaglandin synthesis and bile acid metabolism.