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.

    據美國周一公布的一項研究：某些乳腺癌幸存者吃了大量的水果和蔬菜，其食用量遠遠超過目前美國的準則，可以降低近三分之一的腫瘤復發風險。這一發現僅適用于那些在治療后沒有潮熱的婦女，研究人員說， — 一項調查結果表明水果和蔬菜可作用于雌激素。 

    他們的分析給出了一項解釋，為什么一些研究表明，多吃水果和蔬菜降低了乳腺癌復發的風險，而在其他方面則沒有解釋。這可能取決于個別病人。他們的報告發表在臨床腫瘤學雜志上。

    幫助領導這項研究的加州大學戴維斯分校的埃倫．戈爾德說：“有潮熱的早期乳腺癌患者比沒有潮熱的早期乳腺癌患者有更好的存活率并降低復發率。“

    一些研究已經表明了這一點。而這項研究表明，經過乳腺癌治療后有潮熱的婦女的雌激素水平低于治療后沒有潮熱的婦女。

    研究人員說，由于雌激素誘發了最常見類型的乳腺癌，這表明，食用超量的水果和蔬菜-超出了美國政府所建議的一天5份的量—可降低癌癥幸存者體內有害的雌激素水平。 

    加州大學圣迭戈分校的約翰．皮爾斯說：“看來，一個高水果、蔬菜和纖維的膳食模式已經顯示出其減少循環雌激素水平的作用，它可能只對于循環雌激素水平超過某一閾值的婦女是重要的。”

    研究人員再次檢查了在一項研究中來自3000名乳腺癌患者的數據，其目的在于查看是否低脂肪及高水果和蔬菜飲食可以預防癌癥復發。

    這樣的飲食已被證明在降低曾經患有乳腺癌患者的總體風險方面居于首位。

    研究人員寫道：“我們將膳食干預組與執行每天5份飲食準則的一組作了比較。”這些女性平均年齡53歲，她們中一半被告知要加倍其水果和蔬菜的攝入量，每天10份，多吃纖維并降低脂肪攝入量，超過了政府的建議。

    原3000名乳腺癌幸存者中約百分之三十的人表示，她們沒有潮熱—一種乳腺癌治療中常見的副作用。

    研究人員仔細地察看了這些婦女的數據后發現，在加倍其水果和蔬菜飲食的婦女中只有百分之十六的人在七年后腫瘤復發，而那些被建議按照膳食準則進食的婦女的復發率則是百分之二十三。

    對于已經過了更年期的婦女，如果進食沙拉、水果和其他植物性食物將減少百分之四十七的乳腺癌風險。