送交者: Latino2 于 2005-9-25, 20:56:45:
这项实验调查了一万两千名荷兰妇女， 发现左撇子妇女得乳腺癌的机率比右撇子高两倍以上。实验考虑了被调查者的家族乳腺癌病史，社会经济状况， 抽烟与否等多项因素, 以排除可能造成的误差。
左撇子妇女得乳腺癌的机率相对高的原因尚不明确。一个可能的解释是胎儿时子宫里性激素含量过高导致左撇子形成的同时， 也埋下了以后影响乳房组织的伏笔。
(左撇子在胎儿时就已决定了。 以前的超声扫描研究发现， 如果10-12周的胎儿大多吮吸左手，那么他们长大后就是左撇子。反之，则是右撇子。以前的研究发现， 胎儿出生前子宫里的性激素含量过高是导致左撇子形成的主要原因。)
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Left handedness may be linked to an increased risk of breast cancer, finds new research published online by the BMJ today Researchers in the Netherlands examined the relation between handedness and incidence of breast cancer in over 12,000 healthy, middle aged women born between 1932 and 1941.
Body measurements were taken and risk factors such as social and economic status, smoking habits, family history of breast cancer, and reproductive history were recorded. They found that left handed women were more than twice as likely to develop premenopausal breast cancer as non-left handed women. Adjusting for risk
factors hardly affected the overall association. The origin of the association may lie in exposure to high levels of sex hormones before birth, which can induce left handedness as well as changes in breast tissue, say the authors. "Although the underlying mechanisms remain elusive, our results support the hypothesis that left handedness is related to increased risk of breast
cancer," they conclude.
Source: British Medical Journal On Line First. Sep. 25, 2005