戴胸罩和乳腺癌有關嗎----與潤濤閻討論

作者：南泥灣

昨日，你在《摘下乳罩吧----生命在於忽悠》的文中聲稱：“經過嚴格取樣對比研究，美國5000多不戴乳罩的女性，平時只是穿比較厚大的上衣以達到遮掩的目的，比天天戴乳罩的女性，乳腺癌發病率相差20倍之巨！ 首先，這與戴乳罩者的職業、收入無關。這樣的調查研究誤差極小，因為只要找到不戴乳罩的女性，就很容易找到職業、經濟狀況、年齡以及所有值得研究的指標完全相同的女性做對照從事統計研究。 其次，這與種族無關。不論是白人黑人，也不論美國人還是歐洲人，研究得出的結論都是一致的。“

對此結論我表示懷疑，覺得證據不足。

首先，

上述5000多不戴乳罩的女性比天天戴乳罩的女性，乳腺癌發病率相差20倍之巨，該說法是否來南方周末科學/健康記者李虎軍所說的一本書：Dressed to Kill: The Link Between Breast Cancer and Bras, 1995，作者為Institute for the Study of Culturogenic Disease的Sydney Singer和Soma Grismaijer。美國癌症協會網站上有人稱這種說法為謠言，因為兩位人類學家作者的研究不符合流行病學研究的標準，其數據不可信（“Their study was not conducted according to standard principles of epidemiological research and did not take into consideration other variables, including known risk factors for breast cancer. There is no other, credible research to validate this claim in any way.”）。

目前的數據，美國的乳腺癌發病率為130/10萬，中國的天津低於30/10萬，北京高於40/10萬，上海超過60/10萬（大約是2000年的數據，28萬人普查結果）。即使是發病率最高的上海，也還不到美國平均水平的一半。按此發病率推算，美國5000人只有6.5個得病，樣本量太小了，不能說明問題。

如有其他出處，請告知。

其次，

你給出的一篇哈佛大學文章的摘要沒有證明上述觀點，只說用大胸罩的人得乳腺癌的危險加大。“〔Eur J Cancer. 1991;27(2):131-5.〕 Bra cup size and handedness were studied as possible risk factors for breast cancer. Data for 3918 cases and 11,712 controls from 7 centres were used to examine the association of handedness with laterality of breast cancer; data for 2325 cases and 7008 controls from 4 centres were used to assess the relation of bra cup size to breast cancer risk. There was a suggestive (P about 0.10) association of handedness with breast cancer laterality: odds ratio of a left-handed (or ambidextrous) woman having a left-sided cancer 1.22 (95% CI 0.96-1.56). Handedness may affect the lateral occurrence of breast cancer, although this tumour is in general more common in the left breast, possibly because this breast is usually slightly larger. Premenopausal women who do not wear bras had half the risk of breast cancer compared with bra users (P about 0.09), possibly because they are thinner and likely to have smaller breasts. Among bra users, larger cup size was associated with an increased risk of breast cancer (P about 0.026), although the association was found only among postmenopausal women and was accounted for, in part, by obesity. These data suggest that bra cup size (and conceivably mammary gland。”

因為該摘要總結的3個結論中前兩個統計學上不能成立（P大於0.05）,只有第3個結論有統計學意義，這個結論認為，大杯胸罩增加了乳腺癌的發病率。沒有證明是否戴胸罩和乳腺癌有關。

瑞典Lund 大學的Helena Jernström等發文質疑上述結論的可靠性，因為他們發現：胸罩大小與胸圍有關，而且不同牌子的大小並不一致，需要考慮胸圍後再看看是否有顯著差別
(Int,J Cancer,2006 Nov 1;119(9):2242-3; author reply 2244)。

再次，

我用“bra and breast cancer”在Pubmed( 生物醫學檢索)只能找到35篇論文，看了一下，沒有太明顯的證據表明戴胸罩和乳腺癌有關。是否還有其他更有說服力的論文？請告訴我。

話說回來，即使有幾篇論文提示戴胸罩和乳腺癌有關，下結論還要審慎，畢竟這是統計相關分析，如果樣本量很大且重複性很好，才能為大家所接受。當然，如果你的文章只是愚人節的玩笑，則當別論。

2007-4-2