关于mammogram 的辐射危险

来源: viewfinder 于 2013-12-09 08:06:48 [档案] [博客] [旧帖] [给我悄悄话] 本文已被阅读：次 (6210 bytes)

本文内容已被 [ viewfinder ] 在 2013-12-11 13:58:41 编辑过。如有问题，请报告版主或论坛管理删除.

这是接上文的讨论：

http://bbs.wenxuecity.com/anticancer/400713.html

今天有点时间，讨论一下。其实wiki 上的总结比较全面（原文附在结尾）。

总结一下信息：

1. 目前有很大争议，唯一共识的是越年轻开始mammogram筛查，辐射危险越大，大部分专家不推荐35岁以下女性开始筛查，除有特殊情况。

2. 40岁以上女性是否应该每年做mammogram？这是现在争议的焦点。美国癌症协会仍然推荐年检，NCI的推荐是40到49岁之间一年或两年做一次。但2009年U.S. Preventive Services Task Force的推荐是这个年龄段不要做例行mammogram年检，而是根据个人情况决定。当然这个推荐也有不少医生反对。

3. 现在的情况是，mammogram辐射危险的确切数字很难估算，现在只能说不是0，也不是高得离谱。好处有多大？这个其实也比较难说。我个人感觉，最好还是想明白可能利弊，根据个人情况，与医生讨论后决定。

The radiation exposure associated with mammography is a potential risk of screening. The risk of exposure appears to be greater in younger women. The largest study of radiation risk from mammography concluded that for women 40 years of age or older, the risk of radiation-induced breast cancer was minuscule, particularly compared with the potential benefit of mammographic screening, with a benefit-to-risk ratio of 48.5 lives saved for each life lost due to radiation exposure.^[20] Organizations such as the National Cancer Institute and United States Preventive Task Force take such risks into account when formulating screening guidelines.^[21]

The majority of health experts agree that the risk of breast cancer for asymptomatic women under 35 is not high enough to warrant the risk of radiation exposure. For this reason, and because the radiation sensitivity of the breast in women under 35 is possibly greater than in older women, most radiologists will not perform screening mammography in women under 40. However, if there is a significant risk of cancer in a particular patient (BRCA positive, very positive family history, palpable mass), mammography may still be important. Often, the radiologist will try to avoid mammography by using ultrasound or MRI imaging.

The statistics about mammography and women between the ages of 40 and 55 are the most contentious. A 1992 Canadian National Breast Cancer Study showed that mammography (conducted in the 1980s) had no positive effect on mortality for women between the ages of 50 and 60.^[22]

There is a body of evidence that clearly shows that there is overdiagnosis of cancer when women are screened. These cancers would never have affected these women in their lifetimes. An estimate of this overdiagnosis is 10 breast cancers diagnosed and unnecessarily treated per life saved when 2000 women are screened for 10 years.^[10]

While screening between 40 and 50 is still controversial, the preponderance of the evidence indicates that there is some small benefit in terms of early detection. Currently, the American Cancer Society, the American College of Radiology, and the American Congress of Obstetricians and Gynecologists encourage annual mammograms beginning at age 40.^[23]^[24] ^[25] The National Cancer Institute encourages mammograms one to two years for women ages 40 to 49.^[26] In contrast, the American College of Physicians, a large internist group, has recently encouraged individualized screening plans as opposed to wholesale biannual screening of women aged 40 to 49.^[27] In 2009, the U.S. Preventive Services Task Force recommended that screening of those age 40 to 49 be based on individual's risk factors and values, and that screening should not be routine in this age group.^[28] Their report says that the benefits of screenings before the age of 50 don't outweigh the risks.^[29]