乳癌:吃紅肉會增加風險


  【24drs.com】一篇新研究顯示,婦女在停經前幾年常吃牛排、漢堡和紅肉,其乳癌風險可能會高於蛋白質來源主要是禽類、魚類、蛋類、堅果和豆類的婦女。
  
  麻州波士頓哈佛公衛學院營養系副教授Maryam S. Farvid博士等人在線上發表於6月10日BMJ期刊的報告指出,針對近90,000名婦女進行的分析中,大量攝取紅肉與乳癌相對風險比肉類攝取量最少者高22%有關。
  
  作者們分析了參與「護士健康研究II」研究的88,803名停經前婦女的資料,「護士健康研究II」研究始於1989年,對當時年紀24-43歲的女性護士進行前瞻世代研究,她們平均年齡36.4歲(標準差4.6)。從這些護士們在1991、1995、2003和2007年完成有關飲食頻率的問卷調查中,獲得有關營養方面的資料,問卷詢問在過去一年內對130種食物的一般攝取量。在1998年,這些婦女完成一份探討她們在青春期時飲食攝取的類似問卷。研究對象也提供有關她們乳癌風險因素的資料,包括身高、體重、種族、初經年紀、產次、初次懷孕年紀、停經與否、口服避孕藥的使用情況以及抽菸史。
  
  作者們使用Cox比例風險模式估計相對乳癌風險,他們也進行多變項分析,校正了種族、乳癌家族史、良性乳房疾病史、抽菸史、身高、身體質量指數、初經年齡、產次與初次生育年紀、口服避孕藥使用情況、酒精與熱量攝取、是否停經等。他們在初次分析使用的是1991年問卷的飲食資料,「因為那代表了成年早期的飲食攝取」。
  
  在88,803名婦女、追蹤1,725,419人-年中,共有2,830例侵犯性乳癌:1,511例為停經前、918例已經停經、401例無法確定是否停經。1991年資料發現,相較於攝取紅肉量最少者,攝取紅肉最多者和停經前與停經後婦女後續發生乳癌相對風險(RR)達1.22倍有關(95%信心區間[CI]1.06 - 1.40;趨勢P = .01)。校正總脂肪攝取量(最高與最低五分之一相比較、RR為1.20;95% CI,1.03 - 1.40;趨勢P = .04),蔬果攝取量(RR,1.19;95% CI,1.04 - 1.37;趨勢P = .03),血紅素鐵攝取量(RR,1.21;95% CI,1.04 - 1.41;趨勢P = .03)之後,仍存在正相關。
  
  作者們寫道,當把紅肉攝取量納為模式內的連續變項時,每天每增加一份紅肉,與所有婦女的乳癌風險增加13%有關。校正青春期攝取的紅肉量之後,相對風險並未顯著改變。這個相對風險就數字上看或許不大,但是對乳癌而言,卻是相當高的終身發生率,歸因於紅肉攝取的案例增加絕對數是相當大的,故有其公衛考量。
  
  禽肉類攝取量較高與乳癌風險較低有關(最高與最低五分之一相比較、RR為0.73;95% CI,0.58 - 0.91;趨勢P= .02)。每天每增加一份禽肉類時,與停經後婦女的乳癌風險降低25%有關(RR,0.75;95% CI,0.58 - 0.98)。與停經前癌症風險無關。每天以一份禽肉類取代紅肉,可降低乳癌風險17%(RR,0.83;95% CI,0.72 - 0.96)。每天用一份豆類取代一份肉類,可降低所有婦女之風險達15%(RR,0.85;95% CI,0.73 - 0.98)。此外,每天以綜合魚類、堅果、豆類、禽肉類取代一份肉類時,風險降低14%(RR,0.86;95% CI,0.78 - 0.94)。
  
  作者們寫道,這些結果和其他研究並不一致,其他研究認為紅肉攝取和乳癌風險無關,不過,多數研究結果來自中年之後的飲食分析,而成年早期的紅肉攝取量和乳癌風險增加更相關。致癌的副產物,如高溫烹煮肉類時產生的雜環胺和多環芳香烴;紅肉的動物脂肪和血紅素鐵;刺激肉牛生長的外源性荷爾蒙的殘餘量,這些都是可以解釋大量攝取紅肉和乳癌之關聯的可能機轉。
  
  研究限制包括,研究對象主要是受良好教育的中產白人;依賴食物頻率問卷可能會有誤差;無法控制未知的其他干擾因素,研究強度包括,案例數多,前瞻型設計。
  
  作者們結論表示,這次的分析支持成年早期攝取較多紅肉量和乳癌風險增加有關,並不僅限於停經前婦女之乳癌。與美國癌症協會指引一致的是,成年早期用豆類和禽肉取代未醃製與醃製紅肉,有助於降低乳癌風險。
  
  資料來源:http://www.24drs.com/professional/list/content.asp?x_idno=7093&x_classno=0&x_chkdelpoint=Y
  

Breast Cancer: Red Meat Consumption May Raise Risk

By Norra MacReady
Medscape Medical News

Women who frequently eat steaks, burgers, and other sources of red meat during their premenopausal years may be raising their risk for breast cancer compared with women who get their protein mostly from poultry, fish, eggs, nuts, and legumes, a new study shows.

In an analysis of nearly 90,000 women, heavy consumption of red meat was associated with a relative risk for breast cancer 22% higher than that seen among women at the lowest end of the meat-eating spectrum, Maryam S. Farvid, PhD, Takemi fellow and associate professor from the Department of Nutrition, Harvard School of Public Health, Boston, Massachusetts, and colleagues report in an article published online June 10 in BMJ.

The authors analyzed data from 88,803 premenopausal women participating in the Nurses Health Study II, a prospective cohort study of female registered nurses who were 24 to 43 years of age in 1989, when the study began. Their average age was 36.4 years (standard deviation, 4.6 years). Nutritional information came from food frequency questionnaires the nurses completed in 1991, 1995, 2003, and 2007. The questionnaires asked about usual intake of 130 foods within the past year. In 1998, the women completed a similar questionnaire exploring their food intake during adolescence. The study participants also provided information about other breast cancer risk factors, including height, weight, race, age at first menarche, parity, age at first pregnancy, menopausal status, use of oral contraceptives, and smoking history.

The authors estimated relative breast cancer risk using Cox proportional hazard models. They also performed multivariate analyses, adjusting for race, family history of breast cancer, history of benign breast disease, smoking history, height, body mass index, age at menarche, parity and age at first birth, use of oral contraceptives, intake of alcohol and calories, and menopausal status. They used the dietary information from the 1991 questionnaire in their primary analysis, "as this represents the dietary intake in early adulthood."

There were 2830 cases of invasive breast cancer during 1,725,419 person-years of follow-up of 88,803 women: 1511 premenopausal cases, 918 postmenopausal cases, and 401 cases in which menopausal status was uncertain. Compared with women in the lowest quintile of red meat intake, the highest level of red meat intake in 1991 was associated with a relative risk (RR) of 1.22 for subsequent breast cancer in premenopausal and postmenopausal women (95% confidence interval [CI], 1.06 - 1.40; P for trend = .01). This positive association persisted after adjusting for total fat intake (RR for highest vs lowest fifth, 1.20; 95% CI, 1.03 - 1.40; P for trend = .04), fruit and vegetable consumption (RR, 1.19; 95% CI, 1.04 - 1.37; P for trend = .03), and intake of heme iron (RR, 1.21; 95% CI, 1.04 - 1.41; P for trend = .03).

"When total red meat intake was modeled as a continuous variable, each additional serving/day increase in total red meat was associated with a 13% increase in risk of breast cancer among all women," the authors write. The relative risk did not change significantly after adjusting for red meat intake during adolescence. "When this relatively small relative risk is applied to breast cancer, which has a high lifetime incidence, the absolute number of excess cases attributable to red meat intake would be substantial, and hence a public health concern," the authors write.

Higher levels of poultry intake were associated with a lower risk for breast cancer (RR for highest versus lowest fifth, 0.73; 95% CI, 0.58 - 0.91; P for trend = .02). Each additional daily serving lowered the risk for postmenopausal breast cancer by 25% (RR, 0.75; 95% CI, 0.58 - 0.98). There was no association with premenopausal cancer risk. Replacing 1 daily red meat serving with a serving of poultry lowered breast cancer risk by 17% (RR, 0.83; 95% CI, 0.72 - 0.96). Substituting 1 serving of legumes per day for a serving of meat lowered the risk among all women by 15% (RR, 0.85; 95% CI, 0.73 - 0.98). In addition, risk was lowered by 14% when fish, nuts, legumes, and poultry were combined to substitute for 1 serving/day of meat (RR, 0.86; 95% CI, 0.78 - 0.94).

These findings are not consistent with other studies, in which there was no association between red meat intake and breast cancer risk, the authors write. "However, most of the results have been derived from diet during midlife and later, and red meat intake during early adulthood may be more related to an increased risk of breast cancer. Carcinogenic byproducts such as heterocyclic amines and polycyclic aromatic hydrocarbons, created during high temperature cooking of meat; animal fat and heme iron from red meat; and hormone residues of the exogenous hormones for growth stimulation in beef cattle are some of the mechanisms that may explain the positive association between high intake of red meat and risk of breast cancer."

Study limitations include use of a predominantly white, well-educated, middle-class cohort; reliance on food frequency questionnaires, which usually include some measurement errors; and inability to control for unknown residual confounders. Strengths include the large number of cases and the prospective design.

"This analysis supports an association between higher consumption of total red meat during early adulthood and increased risk of breast cancer that was not clearly restricted to breast cancers in premenopausal women," the authors conclude. "Consistent with the American Cancer Society guidelines, replacement of unprocessed and processed red meat with legumes and poultry during early adulthood may help to decrease the risk of breast cancer."

This study was supported by a grant from the National Institutes of Health. The authors have disclosed no relevant financial relationships.

BMJ. 2014;348:g3437.

    
相關報導
芳香酶抑制劑:對治療癌症有幫助,但有心臟風險?
2016/12/28 上午 09:56:32
中年婦女在停經之前的記憶力優於男性
2016/11/23 下午 02:16:57
較慢開始治療更年期可緩解症狀
2016/10/27 上午 10:25:30

上一頁
   1   2   3   4   5   6   7   8   9   10  




回上一頁