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Chronic Heartburn Poses Cancer Risk
Monday, March 31, 2008
WASHINGTON — Chronic heartburn is a daily acid bath for the esophagus, and complications from it are on the rise.
New U.S. government figures show a worrisome increase in esophagus disorders from severe acid reflux. The worst one, esophageal cancer, is continuing its march as the nation's fastest-growing malignancy.
What to do if you're one of the estimated 3 million Americans whose eroded esophagus means high risk for this especially deadly cancer? More doctors are trying to zap away the worst damage, beaming radiofrequency energy down the throat to burn off precancerous cells.
While it's not yet certain that will block cancer from ever forming, the studies are promising enough that specialists have begun debating how to better find at-risk patients, people who suffer a condition called Barrett's esophagus. Ironically, a damaged esophagus may no longer feel the burn of acid reflux, keeping sufferers in the dark.
\"You become desensitized. You can go a long time without knowing you have Barrett's,\" warns Dr. John I. Allen of the American Gastroenterological Association.
Heartburn sometimes is a temporary problem, but it also can signal gastrointestinal reflux disease, or GERD, where a loose valve allows stomach acid to regularly back up into the delicate esophagus. Millions have GERD, which is on the rise along with expanding waistlines. For most people, acid-suppressing medications are the answer.
But severe reflux over many years can cause serious problems for a fraction of people. The lining of the esophagus erodes until it bleeds, narrows to make swallowing difficult or, worse, starts to repair itself with more acid-resistant intestinal cells that happen to be more cancer-prone. That last condition is called Barrett's esophagus, and sufferers are 30 times more likely than the average person to go on to develop esophageal cancer.
Hospitalizations for all reflux-caused esophageal disorders doubled between 1998 and 2005, says a sobering new count by the U.S. Agency for Healthcare Research and Quality.
Hence a renewed focus on Barrett's patients, to try to prevent their damage from progressing to cancer.
The good news is that esophageal cancer is slow to develop, so Barrett's patients are given regular down-the-throat exams to spot precancerous changes in cells. Those termed \"high-grade dysplasia\" are the most dangerous — one in five of those patients will get full-blown cancer within five years.
Cutting out the esophagus has long been standard treatment to stop high-grade dysplasia from turning into cancer. Do not go straight to that extreme step, say guidelines issued last week by the American College of Gastroenterology.
Instead, the new guidelines urge a two-step process: Send a device down the throat to carefully slice off the precancerous layer and make sure it hasn't already turned into invasive cancer. Then burn away the remaining Barrett's tissue with other endoscopic techniques in hopes of getting healthy cells to grow back in its place — as long as patients stay on long-term, acid-controlling drugs, too.
There are various ways to burn away the problem areas, but specialists increasingly are turning to a device named Barrx that lets them nestle a balloon directly onto the esophagus lining and beam RF energy straight into it.
Small studies suggest Barrx can successfully treat precancerous spots in about 90 percent of patients with no return in two years and counting. Specialists are anxiously awaiting a more in-depth study, to be released later this spring, that compared 120 patients who got either Barrx or a sham procedure.
\"It'll have very impressive results,\" promises Dr. Richard Sampliner of the University of Arizona Health Sciences Center, one of the 19 participating medical centers.
A big question, though, is whether precancerous cells still lurk under the new healthy cells that form, ready to grow again. So patients getting Barrx or other ablation treatments today can't yet abandon regular endoscopic exams.
\"Common sense suggests if we eliminate the Barrett's segment, we're going to eliminate the cancer in people. That really will take decades to know for certain,\" cautions Dr. John Carroll of Georgetown University Hospital.
But Carroll is optimistic enough that this spring, Georgetown begins a study to see if it is worth doing Barrx treatment even earlier — in patients whose Barrett's esophagus hasn't yet developed precancerous spots.
http://www.foxnews.com/story/0,2933,344029,00.html
慢性反酸是食管每天“洗酸浴”，其并发症在上升（WASHINGTON ：Monday, March 31, 2008）。
新美国政府数字显示关于严重返酸导致食管功能紊乱的担忧增加。最严重的就是食管癌——增长最快的恶性肿瘤。
据估计美国有300百万人其腐蚀的食管意味着致命性肿瘤的高风险，如果你是其中之一你该怎么办？越来越多的医生正试图移走最坏的损伤，沿咽喉向下发出等离子刀能量烧毁癌前期细胞。目前尚未确定这样做可以阻止癌症形成，这些研究非常有前景以至于专家们开始争论如何更好的发现患Barrett食管的高危患者。具有讽刺意味的是，已经受损的食管并不能感觉到返酸的烧灼而持续遭受返酸的侵蚀。美国消化学会的John I. Allen警告说：“你们感觉迟钝而不知道已经是Barrett食管了。”
有时返酸只是暂时的，但它也提示了胃食管返流病（GERD）——松弛的瓣膜使得胃酸规律性的返流到食管中。数百万人患有GERD，患病风险随着腰围的增加而呈上升趋势。对于大多数人来说，抑酸药是一种解决方法。但是多年严重的返酸在一部分人中可以引起严重问题。食管腐蚀引起出血、狭窄使吞咽困难或者更有甚者开始肠道细胞化生，这样更容易发生癌症。最后形成Barrett食管，其发展为食管癌的可能性比普通人高30倍。
美国保健研究和质量机构的一项清醒的新数据说1998年到2005年之间因返流而引起食管紊乱住院治疗人数翻倍。因此关于Barrett患者的一项更新焦点是试图阻止患者食管受损进展到癌症。令人庆幸的是食管癌进展缓慢，所以Barrett患者接受常规的食管检查可以发现细胞的癌前病变。那些“高度分化异常”是最危险的——1/5患者将在5年内进展为癌症。常规治疗来阻止高度分化异常的食管转变为食管癌的方法是手术切除。美国胃肠病学会上周的指南说不要一下子就走到最极端的那一步。相反，新指南主张两步走：沿咽喉下置一个设备仔细切下癌前期层，确信还没有转变为浸润性癌症。然后用内窥镜烧灼已有的Barrett组织以期健康细胞在原有部位生长——患者生存多久，抑酸药也要使用多久。
有多种方式烧灼问题区域，但专家们越来越多的转向一种叫做Barrx的设备，这种设备可使患者直接吞下一个球至食管，然后发出等离子能量进入食管。研究表明Barrx可以成功的治疗90%患者的癌前位点而在两年内没有复发。专家们正在焦虑地等待一项更深入的研究——比较120名或者使用Barrx或者使用虚假程序进行治疗的患者，该研究要在今年春末公布。
Arizona 大学健康科学中心的Richard Sampliner允诺：“将会有一些令人印象深刻的结果。”尽管目前大问题是癌前病变的细胞是否潜伏在新生的健康细胞下准备再次生长。所以用Barrx或者其他切割方式治疗的患者并不能放弃常规的食管检查。Georgetown 大学医院的John Carroll提醒道：“如果我们消除了Barrett部分，我们就消除了癌症。那将需要数十年才能明确。”
但是Carroll很乐观，今年春天Georgetown要开始一项研究来看看早期是否值得做Barrx治疗——因为有Barrett食管的患者那时还没有发生癌前病变。 |
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发表于 2008-4-11 16:35:01