USNEWS：肺癌是如何扩散的

最新临床试验：是否接受合并化疗的放射治疗对既往接受过手术的I-IIA期宫颈癌患者影响

2019年3月24日

USNEWS：是肺癌还是别的什么？先不要紧张！

2019年3月27日

发布者 ihealth66 在 2019年3月26日

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By Kathleen Hall

越早发现肺癌，治愈这种疾病的机会就越大。然而，当肺癌细胞扩散到其他器官(转移性疾病)时，癌症通常无法治愈。

肺癌如何传播

纽约大学朗格尼分校珀尔马特癌症中心(NYU Langone’s Perlmutter Cancer Center)肺医学和心胸外科副教授盖塔内·米绍(Gaetane Michaud)说:“癌症在扩散时喜欢做三件事。”“它们在自己的位置上长得更大；它们可以进入淋巴系统，到达一个局部的，区域性的淋巴结，然后到达身体的其他淋巴结；而且肿瘤还能进入血管系统，并通过血液扩散到身体的其他部位。”

米绍说，即使肺癌肿瘤扩散到肺的另一部分，它仍然是一种转移性疾病，因为它是通过血液到达那里的，而不是沿着呼吸道蔓延(在目前的位置变得更大)。“通常的扩散模式是，肿瘤在局部变大，然后扩散到淋巴结，然后扩散到身体的其他部位。”然而，她说，这并不一定遵循这个顺序。在少数病例中，患者可能在肺部有病变，在其他地方有离散性病变，没有淋巴结受累。

米绍说，肿瘤的生长和扩散速度也没有规律可循。“肿瘤可以为所欲为。它们可能增长缓慢，然后突然决定加速。他们可以从一开始就快速增长，也可以是缓慢增长并保持缓慢增长。或者，它们甚至可以在早期快速生长，然后放缓。”你无法预测肿瘤会发生什么。

德克萨斯大学西南医学中心(UT Southwestern Medical Center)教授约翰明纳(John Minna)说，在新近确诊的肺癌患者中，约有三分之一的人有证据表明，这种疾病已经扩散到胸部以外的身体各处。他们需要接受化疗或免疫治疗。他说:“另外三分之一的人的疾病似乎仅限于肺部，有可能被外科医生切除或接受局部放疗。”“剩下的三分之一患者的疾病仍然局限于胸部，但已经扩散到局部淋巴结，可能需要结合化疗、免疫治疗、手术或放疗。”

Minna说，相比之下，当你对没有症状的人进行筛查，并在早期发现肺癌时，80%到90%的病例似乎仅限于肺部。然而，当你观察转移性疾病时，在10%到20%的患者中，你会发现癌症已经扩散了。

发现转移性肺癌

肿瘤学家使用CT扫描和放射性示踪剂PET扫描来发现转移性肺癌，Minna说。CT扫描是最敏感的检查。通过使用染料，CT扫描可以区分肿瘤和正常组织。肿瘤学家通常首先使用CT扫描，Minna说，如果他们发现可疑的东西，他们也会做PET扫描。肿瘤具有代谢活性，并利用糖作为能量。这些活动区域吸收了大量的放射性示踪剂，并在扫描时发光，因此它们有助于发现除最小肿瘤(小于1厘米)以外的所有肿瘤。

米绍说，正电子发射断层扫描有助于发现身体除大脑以外的所有部位的转移性癌症，因为大脑总是处于代谢活跃状态。所以，他们将使用核磁共振成像来发现大脑损伤。PET扫描也不是100%准确。感染和炎症可以作为代谢活跃区出现。她说:“我们不把任何东西称为转移性，直到我们取下它的一部分(活组织切片)。”

肺癌在哪里传播

Minna说，肺癌可以扩散到任何地方，但它倾向于五个部位:肝脏、肾上腺、骨骼、大脑和淋巴结，尤其是在胸部。医生不知道为什么肺癌细胞会扩散到一个区域而不是另一个。然而，Minna说，当肺癌细胞转移到大脑，而不是肝脏时，它可能在生物学上有一些不同的东西，使它能够在那里停留、存活和生长。他说我们才刚刚开始了解这些分子差异。“可能有数百个(癌症)细胞进入了大脑，但可能只有一个‘被拿走了’。“有什么区别吗?”我们知道，我们可以阻止这种差异，所以即使一个细胞进入大脑，它也不能在那里生长。”

治疗转移性肺癌

当患者的肺癌已经扩散，肿瘤学家首先治疗转移的癌症，特别是如果它是在大脑中。如果病人肺部以外只有一个小的病变，外科医生会设法切除它。明纳说，立体定向辐射使用高剂量的非常集中的辐射，在治疗脑转移瘤(和其他一些)方面很有用，因为它只需要很少的治疗，不会引起很多副作用。这可以帮助大脑免受损害。然而，如果癌症已经扩散到多个部位，通常不可能通过手术切除肿瘤。米绍说，在这些病例中，她用全身疗法治疗病人的转移性疾病，如化疗或免疫疗法。“这些疗法可以延长寿命，提高生活质量。”

对于转移性癌症患者，姑息治疗，也称为舒适治疗，是非常重要的。“姑息治疗对病人的预后有很大的影响，”米绍说。“它帮助人们管理症状。早期的姑息干预非常重要。”例如，米肖德可能会从病人的气管中取出肿瘤，以帮助他们更好地呼吸，或者安装一个排水管，以减轻肺部周围有液体的病人的不适。

米绍说，最近在肺癌治疗方面的创新正在延长转移性肺癌患者的寿命。她说，肿瘤学家正在对肿瘤进行分析，找出它们的目标，以便利用人体自身的免疫系统或靶向疗法杀死癌细胞。

THE EARLIER YOU CATCH lung cancer, the better your chances are of curing the disease. However, when lung cancer cells spread to other organs (metastatic disease), the cancer usually becomes incurable.

How Lung Cancer Spreads

“Cancers like to do one of three things when spreading,” says Dr. Gaetane Michaud, an associate professor of pulmonary medicine and cardiothoracic surgery at NYU Langone’s Perlmutter Cancer Center. “They grow bigger in their location. They can get in their own lymphatic system, travel to a local, regional lymph node and go beyond to other lymph nodes in the body. And, tumors can also get into the vasculature and spread to other parts of the body via the bloodstream.”

Even when a lung cancer tumor spreads to another part of the lung, it’s still metastatic disease, Michaud says, because it gets there via the bloodstream instead of extending along the airways (growing bigger in its current location). “The usual pattern of spread is that the tumor gets bigger in its local site and then spreads into the lymph glands and then spreads into other parts of the body.” However, she says, it doesn’t necessarily follow that order. In a minority of cases, a patient might have a lesion in the lung and a discrete lesion somewhere else, with no lymph node involvement.

There’s also no pattern to how fast tumors grow and spread, Michaud says. “Tumors can do whatever they want. They can be slow growing, and then all of a sudden decide to accelerate fast. They can be fast growing from the start or be slow growing and stay slow growing. Or, they can even be fast growing early and then slow down.” You can’t predict what a tumor might do.

In newly diagnosed lung cancer patients, about a third have evidence that the disease has spread outside the chest around the body, says Dr. John Minna, a professor at UT Southwestern Medical Center. They will need to have chemotherapy or immunotherapy. “Another third have disease that appears limited to the lungs and potentially could be resected by a surgeon or treated with local radiotherapy,” he says. “The remaining third of patients have disease that is still localized to the chest but has spread to regional lymph nodes and will likely need some combination of chemotherapy, immunotherapy, surgery or radiation therapy.”

In contrast, Minna says, when you screen people who don’t have symptoms and find lung cancer early, 80 to 90 percent of the cases will appear to be confined to the lung. However, when you look for metastatic disease, in 10 to 20 percent of those patients, you’ll see the cancer has already spread.

Finding Metastatic Lung Cancer

Oncologists use CT scans and PET scans with radioactive tracer to find metastatic lung cancer, Minna says. A CT scan is the most sensitive test. By using a dye, a CT scan can differentiate between tumors and normal tissue. Oncologists usually use a CT scan first, Minna says, and, if they find something suspicious, they also do a PET scan. Tumors are metabolically active and use sugar for energy. These active areas absorb a lot of the radiotracer and light up on a scan, so they’re helpful for finding all but the smallest tumors (less than 1 centimeter).

PET scans are good for finding metastatic cancer in all areas of the body except the brain, which is always metabolically active, Michaud says. So, they’ll use an MRI to find brain lesions. A PET scan is also not 100 percent accurate. Infections and inflammation can appear as metabolically active areas. “We don’t call anything metastatic until we take a piece of it [a biopsy],” she says.

Where Lung Cancer Spreads

While lung cancer can go anywhere, it tends to favor five locations, Minna says: the liver, adrenal glands, bones, brain and lymph nodes, especially in the chest. Doctors don’t know why lung cancer cells spread to one area and not another. However, Minna says, when a lung cancer cell metastasizes to the brain, as opposed to the liver, it probably has something different in its biology that allows it to lodge there, survive and grow. He says we’re just beginning to understand these molecular differences. “It may be that hundreds of [cancer] cells went to the brain, but perhaps only one ‘took.’ What was the difference? It we knew, we could block that difference, so even if a cell went to the brain, it couldn’t grow there.”

Treating Metastasized Lung Cancer

When patients have lung cancer that has spread, oncologists treat the metastasized cancer first, especially if it’s in the brain. If a patient only has one small lesion outside of the lungs, a surgeon will try to remove it. Minna says stereotactic radiation, which uses high doses of very focused radiation, is useful in treating brain (and some other) metastases because it requires only a few treatments and doesn’t cause many side effects. This can help spare the brain from damage. However, if the cancer has spread to multiple locations, it’s usually not possible to remove the tumors surgically. In these cases, Michaud says, she treats patients’ metastatic disease with systemic therapy, such as chemotherapy or immune therapy. “These treatments extend life and improve quality of life.”

For patients with metastatic cancer, palliative care, also called comfort care, is important. “Palliative care has a huge impact on patient outcomes,” Michaud says. “It helps people with symptom management. Early intervention with palliation is really important.” For example, Michaud might remove tumors from patients’ airways to help them breathe better or install a drain to ease discomfort for patients who have fluid around their lungs.

Michaud says recent innovations in lung cancer treatments are extending duration of life for patients with metastatic lung cancer. She says oncologists are profiling tumors and finding out what targets they have in order to use the body’s own immune system or targeted therapies to kill off cancer cells.

Best Hospitals for Cancer

RANK	HOSPITAL NAME	LOCATION
#1	University of Texas MD Anderson Cancer Center	Houston, TX
#2	Memorial Sloan Kettering Cancer Center	New York, NY
#3	Mayo Clinic	Rochester, MN
#4	Dana-Farber/Brigham and Women’s Cancer Center	Boston, MA
#5	Seattle Cancer Alliance/University of Washington Medical Center	Seattle, WA
#6	Johns Hopkins Hospital	Baltimore, MD
#7	Penn Presbyterian Medical Center	Philadelphia, PA
#7	Cleveland Clinic	Cleveland, OH
#9	Moffitt Cancer Center and Research Institute	Tampa, FL
#10	UCSF Medical Center	San Francisco, CA