Breast cancer is the most common cancer in women worldwide.
Early discovery and treatment can save lives.
Scientists are working new ways to recognize breast cancer while at the same time studying existing methods of identification to find out what is best.
Take mammograms, for example. During the test, a technician takes an X-ray picture of a woman's breast as it is pressed between two glass plates. A radiologist then examines the image for signs of cancer.
Mammograms are the best tools available for recognizing the disease. The number of breast cancer deaths has fallen by 30 percent in the United States since doctors began offering mammography in the 1970s. The reason: the chances of beating cancer are higher when the disease is found early.
Yet mammograms are not perfect. A mammogram can look normal even when cancer is present. It can also look abnormal, or unusual, when cancer is not present.
Traditional mammograms are two dimensional (2-D). They show length and width. But for the 40 to 50 percent of women with dense breasts, it is difficult for radiologists to see cancer on 2-D images.
Three-dimensional mammograms provide a more detailed look. So women with dense breasts may get better results from a 3-D mammogram, said Otis Brawley Otis Brawley of the American Cancer Society.
It might find disease that we need to find that two-dimensional does not, Brawley said. He added that 3-D testing costs more and involves higher levels of radiation. It also is not 100 % perfect, he said.
Cost aside, one study involving 13 U.S. hospitals showed that 3-D mammograms recognized an additional 40 percent of invasive cancers.
For better results, a woman could have a whole-breast ultrasound. This test requires the patient to lie on her back as the ultrasound device slowly moves back and forth. The exam captures between 3,000 and 5,000 images of the breast.
Megha Garg is the director of the breast-imaging program at the University of Missouri cancer center. She says the whole-breast ultrasound helps detect additional breast cancers in females who have dense breasts.
The ultrasound doesn't use radiation, so it is less risky than a mammogram. But Garg says the traditional mammogram remains a helpful tool because it is very effective.
Researchers are studying which method is best at detecting cancer.
North America, Western Europe and Australia have the highest rates of breast cancer. Yet the World Health Organization reports that almost 50 percent of the cases and nearly 60 percent of the deaths happen in less-developed countries.
With improvements, nearly 400,000 women's lives could be saved every year.
I'm Susan Shand.
1.find out 找出，弄清
It makes you want to watch the next episode to find out what's going to happen.
2.at the same time 与此同时
You can do anything you want, but not everything at the same time.
3.take sth for example 以……为例
Take for example genetically modified (GM) food.
4.need to do sth 需要做某事
You need to touch up the poem.
5.The number of breast cancer deaths has fallen by 30 percent in the United States since doctors began offering mammography in the 1970s.
begin doing sth 开始做某事
Begin doing what you want to do now.
I sat down and began doing the crossword.
以拍乳房X光片为例 。在测试期间，一位女性会将胸部置于两个玻璃板之间，以进行X光片的拍摄 。随后，放射线研究员会从拍出来的片子上看是否有癌症的迹象 。
拍摄乳房X光片是目前确诊乳腺癌的最好方式 。自从上世纪70年代医生开始提供拍摄乳房X光片的方式后，美国的乳腺癌致死率下降了30% 。原因是：治愈乳腺癌的几率比早期发现乳腺癌的几率要高一些 。
但拍摄乳房X光片并非万能的 。即便某人患有乳腺癌，可能拍出来的X光片也是正常的 。而未患乳腺癌的X光片可能还看起来不正常 。
过去的乳房X光片是二维的，只能看到长度和宽度 。但是对于40%-50%致密型乳腺的女性来说，放射线研究员是很难在二维光片上看出是否有癌症存在的 。
三维的乳腺X光片可以提供许多细节信息 。所以，致密型乳腺的女性或许可以从三维乳房X光片中得到更准确的结果，美国癌症协会的奥蒂斯 布劳利(Otis Brawley)如是说道 。
布劳利表示，三维的乳房X光片可能会发现二维光片无法发现的疾病 。他补充道，三维检测的成本和放射性水准都更高 。不过三维检测也并非十全十美的，布劳利如是说道 。
要想得到更精确的结果，女性也可以对整个乳房进行超声检查 。做这种检查的时候，病人需要仰躺，然后超声装置会缓慢地来回移动 。这种检查可以捕获3000-5000张胸部的图片 。
梅加 加格(Megha Garg)是密苏里大学癌症中心胸片项目的负责人 。她表示，对整个乳房进行超声检查可以帮助致密型乳腺的女性检测出原本检测不到的乳腺癌 。
这种超声波是不含辐射的，所以其危险系数比拍摄X光片低 。但加格表示，传统的X光片拍摄依然有用，因为它很有效果 。
北美、西欧、澳大利亚的乳腺癌比例是最高的 。不过，根据世卫组织的报告，近50%的乳腺癌案例以及近60%的死亡案例都发生在欠发达国家 。
苏珊 尚德为您播报 。