Monroe K R, Murphy S P, Kolonel L N, Pike M C
Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA 90089-9175, USA.
Br J Cancer. 2007 Aug 6;97(3):440-5. doi: 10.1038/sj.bjc.6603880. Epub 2007 Jul 10.
In vitro and in vivo studies have shown that cytochrome P450 3A4 (CYP3A4) is involved in the metabolism of oestrogens. There is evidence that grapefruit, an inhibitor of CYP3A4, increases plasma oestrogen concentrations. Since it is well established that oestrogen is associated with breast cancer risk, it is plausible that regular intake of grapefruit would increase a woman's risk of breast cancer. We investigated the association of grapefruit intake with breast cancer risk in the Hawaii-Los Angeles Multiethnic Cohort Study, a prospective cohort that includes over 50 000 postmenopausal women from five racial/ethnic groups. A total of 1657 incident breast cancer cases were available for analysis. Grapefruit intake was significantly associated with an increased risk of breast cancer (relative risk=1.30, 95% confidence interval 1.06-1.58) for subjects in the highest category of intake, that is, one-quarter grapefruit or more per day, compared to non-consumers (P(trend)=0.015). An increased risk of similar magnitude was seen in users of oestrogen therapy, users of oestrogen+progestin therapy, and among never users of hormone therapy. Grapefruit intake may increase the risk of breast cancer among postmenopausal women.
体外和体内研究表明，细胞色素P450 3A4（CYP3A4）参与雌激素的代谢。有证据表明，CYP3A4的抑制剂葡萄柚会增加血浆雌激素浓度。由于雌激素与乳腺癌风险之间的关联已得到充分证实，因此经常食用葡萄柚可能会增加女性患乳腺癌的风险这一说法是合理的。在夏威夷-洛杉矶多族裔队列研究中，我们调查了葡萄柚摄入量与乳腺癌风险之间的关联，该前瞻性队列研究包括来自五个种族/族裔群体的5万多名绝经后女性。共有1657例新发乳腺癌病例可供分析。与不食用葡萄柚的受试者相比，摄入量最高组（即每天食用四分之一个或更多葡萄柚）的受试者，葡萄柚摄入量与乳腺癌风险增加显著相关（相对风险=1.30，95%置信区间1.06-1.58）（P趋势=0.015）。在接受雌激素治疗的使用者、接受雌激素+孕激素治疗的使用者以及从未接受激素治疗的人群中，也观察到了类似程度的风险增加。食用葡萄柚可能会增加绝经后女性患乳腺癌的风险。
