新研究对乳腺癌X光筛查提出进一步质疑

One of the largest and most meticulous studies of mammography ever done, involving 90,000 women and lasting a quarter century, has added powerful new doubts about the vAlue of the screening test for women of any age.

历史上规模最大、最严格细致的乳房X光检查研究之一，对所有年龄段的女性进行这种筛查的价值提出了强有力的新质疑。这项研究持续了四分之一个世纪之久，涉及9万名女性。

It found that the death rates from breast cancer and from all causes were the same in women who got mammograms and those who did not. And the screening had harms — one out of five cancers found with mammography and treated was not a threat to the woman's health and did not need treatment like chemotherapy, surgery or radiation.

该研究发现，在做过乳房X线检查和没有做过它的女性中，乳腺癌导致的死亡率和所有原因导致的死亡率并无二致。而且这种筛查本身具有危害——通过乳房X光检查发现并进行了治疗的癌症肿块中，有五分之一对女性的健康并不构成威胁，也不需要进行化疗、手术或放疗等治疗。

The study, published Tuesday in The British Medical Journal, is one of the few rigorous evaluations of mammograms conducted in the modern era of more effective breast cancer treatments. It randomly assigned Canadian women to have regular mammograms and breast exams by trained nurses or to have breast exams alone.

这项研究本周二发表在《英国医学杂志》(BMJ)上，在如今这个乳腺癌治疗手段更加有效的时代，对乳房X线检查进行的严格评估寥寥无几，它就是其中一个。在这项研究中，加拿大女性被随机分配给训练有素的护士，进行定期乳房X光检查和乳房检查，或者只进行乳房检查。

Researchers sought to determine whether there was any advantage to finding breast cancers when they were too small to feel. The answer was no, the researchers report.

研究人员希望确定，在乳腺癌肿块太小，患者感觉不到它的时候，发现乳腺癌是否有任何优势。答案是否定的，研究报告称。

The study seems likely to lead to an even deeper polarization between those who believe that regular mammography saves lives, including many breast cancer advocates and patients, and a growing number of researchers who say the evidence is lacking or, at the very least, murky.

这项研究很可能会导致更深的两极分化：一方是相信定期做乳房X光检查可以挽救患者生命的人，包括很多乳腺癌关爱活动倡导者和患者，另一方是越来越多的研究人员，他们认为这种说法缺乏证据，或者至少是证据不明朗。

"It will make women uncomfortable, and they should be uncomfortable," said Dr. Russell P. Harris, a screening expert and professor of medicine at the University of North Carolina. "The decision to have a mammogram should not be a slam dunk."

“这会让女性感到不舒服，她们也理应感到不舒服，”筛查专家、北卡罗莱纳大学(University of North Carolina)医学教授拉塞尔·P·哈里斯(Russell P. Harris)说。“决定做乳房X光检查本来也不应该是一桩乐事。”

The findings will not lead to any immediate change in guidelines for mammography, and many advocates and experts will almost certainly dispute the idea that mammograms are on balance useless, or even harmful.

这些研究结果不会立刻导致乳房X光检查准则的更改，很多倡导者和专家几乎肯定会对“乳房X线检查总体无用，甚至有害”的观点进行质疑。

Dr. Richard C. Wender, chief of cancer control for the American Cancer Society, said the society has convened an expert panel that is reviewing all studies on mammography, including the Canadian one, and would issue revised guidelines later this year. He added that combined data from clinical trials of mammography showed it reduces the death rate from breast cancer by at least 15 percent for women in their 40s and by at least 20 percent for older women.

理查德·C·文德(Richard C. Wender)博士是美国癌症协会(American Cancer Society)癌症控制主任，他说该协会已经召集了一个专家小组，正在审查和乳房X光检查有关的所有研究，加拿大的这项研究也包括在内，今年晚些时候，他们将发布修订后的准则。他还说，乳房X光检查的临床试验的综合数据显示，在40多岁的女性中，乳房X光检查至少降低了15%的乳腺癌死亡率，在年龄更大的女性中降低了至少20%。

That means that one woman in 1,000 who starts screening in her 40s, two who start in their 50s and three who start in their 60s will avoid a breast cancer death, Dr. Harris said.

这意味着，在40多岁开始筛查的1000名女性中，有一名将避免死于乳腺癌，50岁开始的有两名，60岁开始的有三名，哈里斯博士说。

Dr. Wender added that while improved treatments clearly helped lower the breast cancer death rate, so did mammography, by catching cancers early.

文德博士指出，改善后的治疗方法显然有助于降低乳腺癌死亡率，做乳房X光检查也是一样，因为可以提早发现癌症。

But an editorial accompanying the new study said that earlier studies that found mammograms helped women were done before the routine use of drugs like tamoxifen that sharply reduced the breast cancer death rate. In addition, many studies did not use the gold-standard methods of the clinical trial, randomly assigning women to be screened or not.

但跟这项新研究同时发表的一篇社论说，那些发现乳房X光检查有利于女性的早期研究，是在如今常规使用的药物大幅降低乳腺癌死亡率之前进行的，这些药物包括他莫昔芬(Tamoxifen)；此外，很多研究没有采用标准最高的临床试验方法，随机分配女性是否接受筛查。

Dr. Mette Kalager, an epidemiologist and screening researcher at the University of Oslo and the Harvard School of Public Health who wrote the editorial, said there was a reason its results were unlike those of earlier studies. With better treatments, like tamoxifen, it was less important to find cancers early. Also, she said, women in the Canadian studies were aware of breast cancer and its dangers, unlike women in earlier studies who were more likely to ignore lumps.

这篇社论的作者梅特·卡拉格(Mette Kalager)博士是奥斯陆大学(University of Oslo)和哈佛大学公共卫生学院(Harvard School of Public Health)的流行病学家和筛查研究员，她表示，这项研究的结果不同于早期的那些研究是有原因的。有了更好的治疗手段，比如他莫昔芬，提早发现癌症肿块就不那么重要了。此外她还表示，加拿大那项研究中的女性了解乳腺癌及其危险，而早期研究中的女性更有可能会忽视肿块。

"It might be possible that mammography screening would work if you don't have any awareness of the disease," she said.

“如果你完全没有乳腺癌的意识，乳房X光检查就有可能效果不错，”她说。

The Canadian study reached the same conclusion about the lack of a benefit from mammograms after 11 to 16 years of follow-up, but some experts predicted that as time went on the advantages would emerge.

在进行了11到16年的复查随访后，加拿大这项研究得出了乳房X线检查没有裨益的同样结论。但一些专家预计，随着时间的推移，乳房X线检查的优势将会显现。

That did not happen, but with more time the researchers could, for the first time, calculate the extent of overdiagnosis, finding cancers that would never have killed the women but that led to treatments that included surgery, chemotherapy and radiation.

这种情况还没有出现，但因为多花了一些时间，研究人员首次计算出了过度诊断的程度，即针对绝不会令女性丧生的癌症肿块，实施手术、化疗和放疗等治疗手段。

Many cancers, researchers now recognize, grow slowly, or not at all, and do not require treatment. Some cancers even shrink or disappear on their own. But once cancer is detected, it is impossible to know if it is dangerous, so doctors treat them all.

研究人员现在认识到，很多癌症肿块生长缓慢，或根本不生长，也不需要治疗。有些癌症肿块甚至会萎缩或自行消失。但是，一旦癌症肿块被检测到，你就不知道它是否会带来危险，所以医生会统统进行治疗。

In the United States, about 37,000,000 mammograms are performed annually at a cost of about $100 per mammogram. Nearly three-quarters of women age 40 and over say they had a mammogram in the past year. More than 90 percent of women ages 50 to 69 in several European countries have had at least one mammogram.

美国每年大约要做3700万例乳房X线检查，每次检查的费用约为100美元（约合人民币600元）。40岁及以上的女性有四分之三表示曾在过去一年里进行过乳房X光检查。在几个欧洲国家，年龄在50至69岁的女性中有超过90%至少进行过一次乳房X光检查。

Dr. Kalager, whose editorial accompanying the study was titled "Too Much Mammography," compared mammography to prostate-specific antigen screening for prostate cancer, using data from pooled analyses of clinical trials. It turned out that the two screening tests were almost identical in their overdiagnosis rate and had almost the same slight reduction in breast or prostate deaths.

卡拉格博士关于这项研究的社论标题是《乳房X光检查泛滥》(Too Much Mammography)，文中使用来自临床试验的汇总分析数据，把乳房X光检查跟前列腺癌的前列腺特异性抗原（PSA）筛查相提并论。数据显示，这两种筛查的过度诊断率几乎相同，在降低乳腺癌或前列腺癌死亡率的效果方面也几乎同样轻微。

"I was very surprised," Dr. Kalager said. She had assumed that the evidence for mammography must be stronger since most countries support mammography screening and most discourage PSA screening.

“我感到非常惊讶，”卡拉格博士说。她原以为支持乳房X光检查的证据肯定会更加有力，因为大多数国家都支持乳房X光筛查，反对PSA筛查。