關於mammogram 的輻射危險

來源: viewfinder 於 2013-12-09 08:06:48 [檔案] [博客] [舊帖] [給我悄悄話] 本文已被閱讀：次 (6210 bytes)

本文內容已被 [ viewfinder ] 在 2013-12-11 13:58:41 編輯過。如有問題，請報告版主或論壇管理刪除.

這是接上文的討論：

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

今天有點時間，討論一下。其實wiki 上的總結比較全麵（原文附在結尾）。

總結一下信息：

1. 目前有很大爭議，唯一共識的是越年輕開始mammogram篩查，輻射危險越大，大部分專家不推薦35歲以下女性開始篩查，除有特殊情況。

2. 40歲以上女性是否應該每年做mammogram？這是現在爭議的焦點。美國癌症協會仍然推薦年檢，NCI的推薦是40到49歲之間一年或兩年做一次。但2009年U.S. Preventive Services Task Force的推薦是這個年齡段不要做例行mammogram年檢，而是根據個人情況決定。當然這個推薦也有不少醫生反對。

3. 現在的情況是，mammogram輻射危險的確切數字很難估算，現在隻能說不是0，也不是高得離譜。好處有多大？這個其實也比較難說。我個人感覺，最好還是想明白可能利弊，根據個人情況，與醫生討論後決定。

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]