乳腺成像市场争夺战硝烟四起

    豪洛捷公司发言人大卫•丹尼尔森表示，没有得到满足的需要正在激发起新的需求。该公司的数字化层析X射线照相组合系统于2月份获得美国食品及药物管理局（FDA）的批准。这种机器的外形和运行机理与典型的乳房X线照相系统非常类似，但它包含了一个高射传感器，这种传感器能够扫描1毫米的乳房组织表层，进而拍摄出乳房的三维图像。虽然通用电气公司在2000年开发出数字化乳房X线照相术，并由此成为这一领域的开拓者，但豪洛捷公司现在是这一产业的领导者，每月销售的乳房X线照相系统占全美销售量的65%。

    通用电气公司的SenoBright系统也于10月份获得了美国食品及药物管理局（FDA）的批准。除了传统的乳房X线扫描以外，该系统还采用对比手法，产生出一种效果得以增强的二次图像。这种对比可以让人们更清晰地解读图像，非常类似于采用核磁共振成像进行后续检查所获得的效果。虽然通用电气公司预期这项新技术的阳性检测结果出错率将“显著”低于当前的乳房X线照相系统，但它依然无法检测出某个肿块是否发生了癌变，而一些医生认为这正是新技术能否成功的重要指标。

    据美国癌症协会（American Cancer Society）统计，美国今年大约有30万名妇女被诊断出患有乳腺癌。纪念斯隆-凯特琳癌症中心（Memorial Sloan-Kettering Cancer Center）乳腺成像部主任伊丽莎白•莫里斯认为，虽然频繁的筛查和早期检测可以降低死亡率，降幅最高可达30%，但乳房X线照相术的“黄金标准”远远不够完善。她说，普通乳房组织中20%的癌病变无法通过乳房X线照片检测出，对于乳房组织更紧密的女性，这一比例甚至高达50%。即使X线真的发现了异常，复诊时也有差不多70%的病人发现这些病变并非阳性，这意味着她们并没有患上癌症。“我完全无法确认，三维成像技术是否能够带来显著的变化，改变这个行业的现状，”莫里斯说。“最重要的问题是，我们什么时候能够植入某种东西，可以让我们看清楚癌病变的位置，同时进行靶向治疗。”

    MD安德森癌症中心（MD Anderson Cancer Center）的约翰•黑兹尔认同这种看法。他说，实际上，这也是MD安德森癌症中心今年8月份同意对爱德华•弗林的磁性纳米颗粒技术进行临床前评估的原因所在。不同于普通的乳房X线照相系统（它只能检测出至少由1亿个癌细胞构成的肿块），弗林的纳米颗粒技术能够检测出由10万个癌细胞构成的肿块，而且经过目前的编程，可检测出的细胞数量将降低至1,2000个。等到这种技术正式投入商用时，它能够在癌细胞发展至第一阶段之前就将其检测出来，可检测出的细胞数量将降至“几千个”，Senior Scientifics公司【现在已隶属于曼哈顿科学公司（Manhattan Scientifics）】总裁杰拉尔德•格拉夫说。“成像技术这条路根本就是错的。治疗癌症不应该盯着形态，而应寻找某种细胞。”

    弗林的技术不是生成某个癌细胞大肿块的图像，而是在纳米粒子附着于癌细胞时发出磁信号。通过这种技术，医生们不仅可以观察到癌细胞的位置，还可以掌握它们的数量。尽管这种技术目前还远远无法获得食品及药物管理局的批准，弗林的梦想很有可能到若干年之后方能实现，但弗林声称，他的工作朝着正确的方向又迈出了一步。

    译者：任文科

    Demand is being stoked by unmet needs, according to David Danielson, a spokesperson for Hologic. In February, the company received FDA approval for its digital tomosynthesis system. The machine looks and works similarly to a typical mammography system, but includes an overhead sensor, which takes a 3D image of the breast by scanning 1-millimeter layers of breast tissue. While GE pioneered the mammography industry in 2000 when it developed the digital mammogram, Hologic is now the industry leader, selling about 65% of mammography systems in the U.S. each month.

    In October, GE received FDA approval for its so-called SenoBright. That system uses contrast to produce an enhanced secondary image in addition to a traditional mammography scan. The contrast allows for a clearer reading of the image, much like you would get in a follow up MRI scan. While the company says it expects the new technology to have a "significantly" lower false positive rate than current mammography systems, it still can't detect whether a mass is cancerous -- a factor some physicians feel is key to new technologies.

    Nearly 300,000 women in the U.S. were diagnosed with breast cancer this year, according to the American Cancer Society. While frequent screening and early detection can lower the mortality rate by up to 30%, the mammography "gold standard" is far from perfect, says Elizabeth Morris, chief of breast imaging at Memorial Sloan-Kettering Cancer Center. Mammograms miss about 20% of cancers in normal breast tissue, and up to 50% in denser breast tissues, she says. And even if the x-ray does manage to pick up an abnormality, roughly 70% of those patients called back will be a false positive, meaning they don't have cancer. "I'm just not sure 3D imaging is going to be a huge game changer," Morris says. "The holy grail is when we're able to inject something that allows us to see where the cancer is and does targeted therapy at the same time."

    John Hazle of MD Anderson Cancer Center agrees. In fact, that's the reason, he says, MD Anderson signed on for a pre-clinical evaluation of Edward Flynn's magnetic nano-particle technology in August this year. Unlike a mammogram, which can only detect a mass of at least 100 million cancer cells, Flynn's nano-particle technology can detect cancer at a mass of 100,000 cells, and is currently being programmed to detect down to 12,000 cells. By the time it's ready for commercial use, it could detect cancer before stage one -- down to "a few thousand cells" says Gerald Grafe, president of Senior Scientifics, now a division of Manhattan Scientifics (MHTX). "Imaging is fundamentally the wrong approach. In cancer, you're not after the shape, you're looking for a kind of cell," Grafe argues.

    Instead of producing an image of a large mass of cancer cells, Flynn's technology produces a magnetic signal when the nano-particles attach to cancer cells. This allows physicians to see not only where the cancer is, but also how many cells there are. While the technology is nowhere near FDA approval, and it'll likely be several years before Flynn's dreams come to fruition, Flynn claims his work is just one more step toward the right approach.