Rogers A E, Hafer L J, Iskander Y S, Yang S
Mallory Institute of Pathology and Department and Laboratory Medicine, Boston University School of Medicine, 02118, USA.
Carcinogenesis. 1998 Jul;19(7):1269-73. doi: 10.1093/carcin/19.7.1269.
Epidemiological studies suggest that tea may reduce cancer risk, and in laboratory rodents, chemopreventive effects of tea or purified extracts of tea have been demonstrated in lung, gastrointestinal tract and skin. There is some evidence of chemoprevention by tea in the mammary gland, but the data are not conclusive. In order to evaluate more fully the possible influence of black tea on 7,12-dimethylbenz[a]anthracene (DMBA)-induced mammary gland tumors in the female S-D (Sprague-Dawley) rat, three large studies were performed: experiment 1, tumorigenesis in rats fed AIN-76A diet and given 25 mg/kg DMBA and 1.25 or 2.5% whole tea extract or water to drink; experiment 2, tumorigenesis in rats given 15 mg/kg DMBA and the same diet and fluids as in experiment 1; experiment 3, tumorigenesis in rats fed control or HF (high fat, corn oil) diet and given 15 mg/kg DMBA and 2% tea or water to drink. Tea was given throughout the experiment; DMBA was given by gastric gavage at 8 weeks of age. There was no consistent effect of tea on tumorigenesis in rats fed AIN-76A diet; there was, however, evidence in experiment 3 of a reduction of tumorigenesis by tea in rats fed the HF diet. In experiment 3, rats fed the HF diet and given water showed the expected increase in tumor burden (number and weight) compared with rats fed control diet. However, rats fed the HF diet and given 2% tea showed no increase in tumor burden; their tumor burden was significantly lower than in rats fed the HF diet and given water (P < 0.01) and was not different from rats fed control diet and given water or tea. In addition, in experiment 3, the number of malignant tumors per tumor-bearing rat was increased by the HF diet in water-drinking rats (P < 0.01) but not in tea-drinking rats. Therefore, it appears that tea partially blocked the promotion of DMBA-induced mammary tumorigenesis by the HF diet.
流行病学研究表明，茶可能降低患癌风险，并且在实验啮齿动物中，茶或茶的纯化提取物在肺、胃肠道和皮肤中已显示出化学预防作用。有一些证据表明茶对乳腺有化学预防作用，但数据并不确凿。为了更全面地评估红茶对雌性S-D（斯普拉格-道利）大鼠中7,12-二甲基苯并[a]蒽（DMBA）诱导的乳腺肿瘤的可能影响，进行了三项大型研究：实验1，给喂食AIN-76A饮食并给予25 mg/kg DMBA以及饮用1.25%或2.5%全茶提取物或水的大鼠进行肿瘤发生研究；实验2，给给予15 mg/kg DMBA以及与实验1相同饮食和液体的大鼠进行肿瘤发生研究；实验3，给喂食对照或HF（高脂肪、玉米油）饮食并给予15 mg/kg DMBA以及饮用2%茶或水的大鼠进行肿瘤发生研究。在整个实验过程中给予茶；在8周龄时通过胃管给予DMBA。茶对喂食AIN-76A饮食的大鼠的肿瘤发生没有一致的影响；然而，在实验3中有证据表明，喂食HF饮食的大鼠中茶可降低肿瘤发生。在实验3中，与喂食对照饮食的大鼠相比，喂食HF饮食并饮水的大鼠的肿瘤负担（数量和重量）出现预期增加。然而，喂食HF饮食并给予2%茶的大鼠的肿瘤负担没有增加；它们的肿瘤负担显著低于喂食HF饮食并饮水的大鼠（P < 0.01），并且与喂食对照饮食并饮水或茶的大鼠没有差异。此外，在实验3中，饮水的大鼠中HF饮食使每只荷瘤大鼠的恶性肿瘤数量增加（P < 0.01），但饮茶的大鼠中没有增加。因此，似乎茶部分阻断了HF饮食对DMBA诱导的乳腺肿瘤发生的促进作用。
