Certain breast cancer survivors who load up on fruits and vegetables, eating far more than current U.S. guidelines, can slash their risk the tumors will come back by nearly a third, according to a U.S. study released on Monday.

    The finding only held for women who did not have hot flashes after their cancer therapy, the researchers said — a finding that suggests fruits and vegetables act on estrogen.

    Their analysis suggests an explanation for why some studies have shown that eating more fruits and vegetables lowers the risk that breast cancer will come back, while others do not. It may depend on the individual patient, they report in the Journal of Clinical Oncology.

    "Women with early stage breast cancer who have hot flashes have better survival and lower recurrence rates than women who don't," said Ellen Gold of the University of California Davis, who helped lead the study.

    Several studies have shown this. And this study showed that women who had hot flashes after treatment for breast cancer had lower estrogen levels than women who did not.

    As estrogen drives the most common type of breast cancer, this suggests that eating extra servings of fruits and vegetables — above and beyond the five servings a day recommended by the U.S. government — may lower harmful estrogen levels in cancer survivors, the researchers said.

    "It appears that a dietary pattern high in fruits, vegetables and fiber, which has been shown to reduce circulating estrogen levels, may only be important among women with circulating estrogen levels above a certain threshold," said John Pierce of the University of California San Diego.

    The researchers took a second look at data from 3,000 breast cancer patients in a study aimed at seeing whether a diet low in fat and high in fruits and vegetables might keep their cancer from coming back.

    Such a diet has been shown to lower overall risk of ever getting breast cancer in the first place.

    The women were on average 53, and half were told to double their fruit and vegetable intake to 10 servings a day, eat more fiber and lower fat intake more than government recommendations. "We compared the dietary intervention group to a group that received '5-a-day' dietary guidelines," the researchers wrote.

    About 30 percent of the original 3,000 breast cancer survivors said they did not have hot flashes — a common side-effect of breast cancer treatment.

    The researchers looked at the data on these women specifically and found that only 16 percent of those who doubled up on fruits and vegetables had their tumors come back after seven years, compared to 23 percent of those merely given advice on food guidelines.

    Women who had been through menopause lowered their risk by 47 percent if they loaded up on salads, fruit and other plant food.

    据美国周一公布的一项研究：某些乳腺癌幸存者吃了大量的水果和蔬菜，其食用量远远超过目前美国的准则，可以降低近三分之一的肿瘤复发风险。这一发现仅适用于那些在治疗后没有潮热的妇女，研究人员说， — 一项调查结果表明水果和蔬菜可作用于雌激素。 

    他们的分析给出了一项解释，为什么一些研究表明，多吃水果和蔬菜降低了乳腺癌复发的风险，而在其他方面则没有解释。这可能取决于个别病人。他们的报告发表在临床肿瘤学杂志上。

    帮助领导这项研究的加州大学戴维斯分校的埃伦．戈尔德说：“有潮热的早期乳腺癌患者比没有潮热的早期乳腺癌患者有更好的存活率并降低复发率。“

    一些研究已经表明了这一点。而这项研究表明，经过乳腺癌治疗后有潮热的妇女的雌激素水平低于治疗后没有潮热的妇女。

    研究人员说，由于雌激素诱发了最常见类型的乳腺癌，这表明，食用超量的水果和蔬菜-超出了美国政府所建议的一天5份的量—可降低癌症幸存者体内有害的雌激素水平。 

    加州大学圣迭戈分校的约翰．皮尔斯说：“看来，一个高水果、蔬菜和纤维的膳食模式已经显示出其减少循环雌激素水平的作用，它可能只对于循环雌激素水平超过某一阈值的妇女是重要的。”

    研究人员再次检查了在一项研究中来自3000名乳腺癌患者的数据，其目的在于查看是否低脂肪及高水果和蔬菜饮食可以预防癌症复发。

    这样的饮食已被证明在降低曾经患有乳腺癌患者的总体风险方面居于首位。

    研究人员写道：“我们将膳食干预组与执行每天5份饮食准则的一组作了比较。”这些女性平均年龄53岁，她们中一半被告知要加倍其水果和蔬菜的摄入量，每天10份，多吃纤维并降低脂肪摄入量，超过了政府的建议。

    原3000名乳腺癌幸存者中约百分之三十的人表示，她们没有潮热—一种乳腺癌治疗中常见的副作用。

    研究人员仔细地察看了这些妇女的数据后发现，在加倍其水果和蔬菜饮食的妇女中只有百分之十六的人在七年后肿瘤复发，而那些被建议按照膳食准则进食的妇女的复发率则是百分之二十三。

    对于已经过了更年期的妇女，如果进食沙拉、水果和其他植物性食物将减少百分之四十七的乳腺癌风险。