根據(jù)文章的背景資料：“在美國(guó),，男子在一生中罹患前列腺癌的風(fēng)險(xiǎn)目前估計(jì)為16%。盡管大多數(shù)的病例是在早期,、可治愈的階段被發(fā)現(xiàn)的,，但該病治療成本高，而且泌尿功能,、性功能和與腸道相關(guān)的不良反應(yīng)很常見(jiàn),。”有關(guān)硒和維生素E可降低前列腺癌風(fēng)險(xiǎn)的臨床前及流行病學(xué)的證據(jù)是相當(dāng)多的。 “在2008年12月發(fā)表的有關(guān)硒與維生素E癌癥預(yù)防試驗(yàn)（SELECT）的最初的報(bào)告發(fā)現(xiàn),，無(wú)論是硒或是維生素E補(bǔ)充劑都不會(huì)降低前列腺癌的風(fēng)險(xiǎn),，而維生素E卻會(huì)令前列腺癌的罹患風(fēng)險(xiǎn)出現(xiàn)非統(tǒng)計(jì)意義上的增加。較長(zhǎng)的跟蹤時(shí)間以及更多的前列腺癌事件令人們對(duì)維生素E與前列腺癌之間的關(guān)系有了進(jìn)一步的了解,。”
克里夫蘭診所的Eric A. Klein, M.D.及其同事對(duì)維生素E和硒對(duì)相對(duì)健康的男性的前列腺癌罹患風(fēng)險(xiǎn)的長(zhǎng)期效應(yīng)進(jìn)行了調(diào)查,。在select 中共有來(lái)自美國(guó)、加拿大和波多黎各的427個(gè)研究場(chǎng)所的3萬(wàn)5533名男子,，他們是在2001年8月至2004年6月間進(jìn)入這一隨機(jī)化的試驗(yàn)中的,。加入該研究的資格標(biāo)準(zhǔn)包括年齡在50歲或以上的黑人男子及年齡在55歲以上的其他種族男子，他們的前列腺特異性抗原（PSA）的測(cè)量低于某個(gè)濃度,，直腸指檢也沒(méi)有懷疑他們罹患了前列腺癌,。初步的分析包括了3萬(wàn)4887名男子，他們被隨機(jī)分派到4個(gè)治療組中的1組：8752人服用硒（200毫克/日）,；8737人服用維生素E（400IU/日）,；8702人服用硒和維生素E；8696人服用安慰劑,；對(duì)這些受試者的計(jì)劃跟蹤時(shí)間最短為7年,，最長(zhǎng)為12年。分析反映的是由研究場(chǎng)所收集的他們的受試者的直到2011年7月5日時(shí)的最終數(shù)據(jù),。
自最初的報(bào)告以來(lái),，另外還有總共521人被診斷罹患了前列腺癌：113人來(lái)自安慰劑組，147人來(lái)自維生素E組,，143人來(lái)自硒組,，118人來(lái)自組合服藥組。研究人員發(fā)現(xiàn)，在所有的治療組中所發(fā)現(xiàn)的前列腺癌的發(fā)生率都高于安慰劑組,，但只有維生素E組與安慰劑組的差異具有統(tǒng)計(jì)學(xué)上的顯著性（即發(fā)現(xiàn)的前列腺癌發(fā)生率增加了17%）,。與安慰劑組相比（該組有529人出現(xiàn)了前列腺癌），在維生素E組中有620人出現(xiàn)了前列腺癌,，在硒組中有575人出現(xiàn)了前列腺癌,，在硒加維生素E組中有555人出現(xiàn)了前列腺癌。在該試驗(yàn)的第三年,，維生素E組與安慰劑組之間的前列腺癌發(fā)生率的差異變得明顯,。維生素E組中的低度和高度前列腺癌的預(yù)計(jì)風(fēng)險(xiǎn)都有所增加,。
“所觀察到的前列腺癌發(fā)生率增加了17%表明,，看來(lái)無(wú)害但卻有生物活性的物質(zhì)（如維生素等）可能會(huì)引起損害。維生素E或其它制劑作為食物補(bǔ)充劑在預(yù)防常見(jiàn)的健康問(wèn)題和癌癥或提高總體存活率方面的裨益的缺乏,，以及它們有可能造成傷害等都強(qiáng)調(diào)了在沒(méi)有臨床試驗(yàn)所證明的強(qiáng)有力的裨益證據(jù)時(shí),，消費(fèi)者有必要對(duì)未加監(jiān)督的非處方性柜臺(tái)銷售的產(chǎn)品所聲稱的對(duì)健康的益處持懷疑態(tài)度。”(生物谷 Bioon.com)
doi:10.1001/jama.2011.1437
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Vitamin E and the Risk of Prostate Cancer
Eric A. Klein, MD; Ian M. Thompson, Jr, MD; Catherine M. Tangen, DrPH; John J. Crowley, PhD; M. Scott Lucia, MD; Phyllis J. Goodman, MS; Lori M. Minasian, MD; Leslie G. Ford, MD; Howard L. Parnes, MD; J. Michael Gaziano, MD, MPH; Daniel D. Karp, MD; Michael M. Lieber, MD; Philip J. Walther, MD, PhD; Laurence Klotz, MD; J. Kellogg Parsons, MD, MHS; Joseph L. Chin, MD; Amy K. Darke, MS; Scott M. Lippman, MD; Gary E. Goodman, MD; Frank L. Meyskens, Jr, MD; Laurence H. Baker, DO
Context The initial report of the Selenium and Vitamin E Cancer Prevention Trial (SELECT) found no reduction in risk of prostate cancer with either selenium or vitamin E supplements but a statistically nonsignificant increase in prostate cancer risk with vitamin E. Longer follow-up and more prostate cancer events provide further insight into the relationship of vitamin E and prostate cancer.
Objective To determine the long-term effect of vitamin E and selenium on risk of prostate cancer in relatively healthy men.
Design, Setting, and Participants A total of 35 533 men from 427 study sites in the United States, Canada, and Puerto Rico were randomized between August 22, 2001, and June 24, 2004. Eligibility criteria included a prostate-specific antigen (PSA) of 4.0 ng/mL or less, a digital rectal examination not suspicious for prostate cancer, and age 50 years or older for black men and 55 years or older for all others. The primary analysis included 34 887 men who were randomly assigned to 1 of 4 treatment groups: 8752 to receive selenium; 8737, vitamin E; 8702, both agents, and 8696, placebo. Analysis reflect the final data collected by the study sites on their participants through July 5, 2011.
Interventions Oral selenium (200 μg/d from L-selenomethionine) with matched vitamin E placebo, vitamin E (400 IU/d of all rac-α-tocopheryl acetate) with matched selenium placebo, both agents, or both matched placebos for a planned follow-up of a minimum of 7 and maximum of 12 years.
Main Outcome Measures Prostate cancer incidence.
Results This report includes 54 464 additional person-years of follow-up and 521 additional cases of prostate cancer since the primary report. Compared with the placebo (referent group) in which 529 men developed prostate cancer, 620 men in the vitamin E group developed prostate cancer (hazard ratio [HR], 1.17; 99% CI, 1.004-1.36, P = .008); as did 575 in the selenium group (HR, 1.09; 99% CI, 0.93-1.27; P = .18), and 555 in the selenium plus vitamin E group (HR, 1.05; 99% CI, 0.89-1.22, P = .46). Compared with placebo, the absolute increase in risk of prostate cancer per 1000 person-years was 1.6 for vitamin E, 0.8 for selenium, and 0.4 for the combination.
Conclusion Dietary supplementation with vitamin E significantly increased the risk of prostate cancer among healthy men.
