戴胸罩和乳腺癌有关吗----与润涛阎讨论

作者：南泥湾

昨日，你在《摘下乳罩吧----生命在于忽悠》的文中声称：“经过严格取样对比研究，美国5000多不戴乳罩的女性，平时只是穿比较厚大的上衣以达到遮掩的目的，比天天戴乳罩的女性，乳腺癌发病率相差20倍之巨！ 首先，这与戴乳罩者的职业、收入无关。这样的调查研究误差极小，因为只要找到不戴乳罩的女性，就很容易找到职业、经济状况、年龄以及所有值得研究的指标完全相同的女性做对照从事统计研究。 其次，这与种族无关。不论是白人黑人，也不论美国人还是欧洲人，研究得出的结论都是一致的。“

对此结论我表示怀疑，觉得证据不足。

首先，

上述5000多不戴乳罩的女性比天天戴乳罩的女性，乳腺癌发病率相差20倍之巨，该说法是否来南方周末科学/健康记者李虎军所说的一本书：Dressed to Kill: The Link Between Breast Cancer and Bras, 1995，作者为Institute for the Study of Culturogenic Disease的Sydney Singer和Soma Grismaijer。美国癌症协会网站上有人称这种说法为谣言，因为两位人类学家作者的研究不符合流行病学研究的标准，其数据不可信（“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.”）。

目前的数据，美国的乳腺癌发病率为130/10万，中国的天津低于30/10万，北京高于40/10万，上海超过60/10万（大约是2000年的数据，28万人普查结果）。即使是发病率最高的上海，也还不到美国平均水平的一半。按此发病率推算，美国5000人只有6.5个得病，样本量太小了，不能说明问题。

如有其他出处，请告知。

其次，

你给出的一篇哈佛大学文章的摘要没有证明上述观点，只说用大胸罩的人得乳腺癌的危险加大。“〔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。”

因为该摘要总结的3个结论中前两个统计学上不能成立（P大于0.05）,只有第3个结论有统计学意义，这个结论认为，大杯胸罩增加了乳腺癌的发病率。没有证明是否戴胸罩和乳腺癌有关。

瑞典Lund 大学的Helena Jernström等发文质疑上述结论的可靠性，因为他们发现：胸罩大小与胸围有关，而且不同牌子的大小并不一致，需要考虑胸围后再看看是否有显著差别
(Int,J Cancer,2006 Nov 1;119(9):2242-3; author reply 2244)。

再次，

我用“bra and breast cancer”在Pubmed( 生物医学检索)只能找到35篇论文，看了一下，没有太明显的证据表明戴胸罩和乳腺癌有关。是否还有其他更有说服力的论文？请告诉我。

话说回来，即使有几篇论文提示戴胸罩和乳腺癌有关，下结论还要审慎，毕竟这是统计相关分析，如果样本量很大且重复性很好，才能为大家所接受。当然，如果你的文章只是愚人节的玩笑，则当别论。

2007-4-2