VOA 常速 - 医生们揭示有可能用于对抗脑癌的潜在新工具

Doctors Unveil Potential New Tool to Fight Brain Cancer

The blood-brain barrier is a natural defense system that prevents harmful substances in the blood from entering the brain. Doctors may have found a way to get past the barrier to treat cancer patients.

Neurosurgeons have been using lasers to treat brain cancer since 2009, but now they say the technique may also allow them to deliver chemotherapy drugs directly into the brain.

The key is getting past the protective blood-brain barrier, which does its job so well it also keeps out potentially lifesaving chemotherapy drugs.

Kathy Smith has ovarian cancer that spread to her brain, a type of brain cancer called glioblastoma.

“There were I believe three tumors at that time and I was not at all happy about those critters,” she said.

Smith was treated with laser therapy. Doctors insert a tiny probe into the brain, directly to the cancer where it burns up the tumor from the inside out.

According to Washington University Neurosurgery Professor Eric Leuthardt, during the procedure it was discovered the therapy had an unintended effect on the blood-brain barrier.

“We were able to show that this blood-brain barrier is broken down for about four weeks after you do this laser therapy," he said. "So not only are you killing the tumor, you are actually opening up a window of opportunity to deliver various drugs and chemicals and therapies that could otherwise not get in there.”

In Kathy's case, a powerful, experimental chemotherapy drug called doxorubicin, which has been notoriously hard to get past the barrier was delivered directly into her brain.

“What is interesting is the blood-brain barrier is a two-way street," said Eric Leuthardt. "By breaking it down you can get things into the brain, but also by breaking it down, now things can go from your brain out into your circulation, to your peripheral system, which includes your immune system.”

And the immune system helps fight cancer.

The procedure is dangerous, a compromised blood-brain barrier puts the brain at risk, but so far it has worked well for Smith. Patients diagnosed with glioblastoma tumors usually survive just 15 months after diagnosis.

But Smith has been fighting her cancer since 2009.

“Kind of makes you smile when they say you are a good candidate for something new," she said. "So I got worked into that study and it did work out beautifully.”

The team of neurosurgeons, from Washington University in St. Louis are hoping to publish a more formal report on their work later this year.

血脑屏障是身体自然的防御系统，能阻止某些有害物质由血液进入到大脑。如今，医生们可能已经找到一种方法能穿过这层屏障治疗脑癌病患。

自2009年以来，神经外科医生一直使用激光来治疗脑癌患者，但现在，医生们发现了新的技术，可能使得化疗药物能直接进入患者的脑部。

这项技术的要诀在于必须要将药物穿过负责保护大脑的血脑屏障，血脑屏障的防御功能阻止了部分潜在能治病的化疗药物进入大脑。

凯西.史密斯罹患卵巢癌并扩散到大脑，这一类型的脑癌称之为胶质母细胞瘤。

她说：“那时我好像一共有3颗肿瘤，因为这些东西，当时的我一点都不开心。”

史密斯原本接受的是激光治疗。医生将极微小的探针穿进她的大脑，直接扎进肿瘤，然后用激光把肿瘤烧毁。

华盛顿大学神经外科教授艾瑞克.路德哈特说，在治疗过程中，他们发现这样的治疗方式对血脑屏障产生了一种意想不到的效果。

他说：“我们发现在经过大约4个星期的激光治疗后，血脑屏障出现破洞。也就是说，我们不只消灭了肿瘤，也为施放其他药物、化学药剂或治疗方式等开启了一个窗口，否则这些东西通常都会被血脑屏障给阻挡在外。”

以史密斯的例子来说，强效试验化疗药物 “多柔比星”本来无法穿过血脑屏障，但现在得以进入到她的大脑。

路德哈特说：“有趣的是，血脑屏障是个双向道。如果它被破坏了，代表你能将东西送进大脑里，但同样的，一些东西也会借由身体的循环从大脑中传出，并到达其他外部系统，包括免疫系统。”

免疫系统协助抵抗癌症。

不过，这样的过程是有危险性的。遭到破坏的血脑屏障让大脑处在受伤的风险中。尽管如此，这样的治疗方式至今对史密斯来说是有效的。被诊断出胶质母细胞瘤的病患通常在发现后只能存活15个月。

但史密斯从2009年就已经开始和癌症病魔奋斗了。

她说：“当他们说我是某种新药物或新方法很好的实验人选时，让我有点高兴，所以我加入了他们的研究，结果非常好。”

圣路易斯华盛顿大学的神经外科团队希望在今年晚些时候能就他们的研究结果发表一份正式的报告。