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华人最佳的胃肠癌症普查方法 (2)
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  • 作者: 叶医师信箱
  • 来源: Jeff H. Ye,MD/Ph.D
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华人最佳的胃肠癌症普查方法 (2)


华青医师,Jeff H. Ye,MD/Ph.D


诊所有很多来年度体检的50岁以上的华人经常询问这个问题。由于现在是信息时代,大家都是有备而来做过一些互联网的搜索研究,然而互联网上登出来的信息魚龙混杂,我常常不得不花相当的时间去解答这些问题。希望这篇文章能够帮助华人了解这方面的信息。


本文的重点在于介绍各种胃肠癌症的检查方法尤其是华人常见的胃肠肿瘤。现根据华人中的发病率次序依次介绍如下。
第一名:肝癌。 第二名:胃癌和食管癌

第三名:大肠癌
肠癌对生活在美国的华人应该是不陌生的,它是美国死亡率和发病率最高的前三名的恶性肿瘤,随着大肠癌大面积的普查,其死亡率有非常明显的下降。中国国内的大肠癌发病率近年来呈明显上升的趋势,据2012调查己跃升为所以癌症发病率的第五名,有迅速与国际接轨的态势。几十年前在加州的一个著名的研究发现曰本第一和第二代移民大肠癌发病率明显高于同时代日本本土居民,饮食结构和习惯的变化是主要原因。然而第一代移民不仅大肠癌发病率升高但是其胃癌的发病率却未见下降,其原因可能与移民前胃幽门螺旋杆菌感染有关。估计华人第一代移民的情况和日本移民差不多。然而前几年在NewJersey有一个关于印度移民大肠发病率的调查发现印度移民大肠癌发病率仅为白人的十分之一。现尚末看到有关美国华人大肠癌发病率的报告。

美国癌症学会提荐的大肠癌普查方法有大便潜血检查,大便大肠癌DNA 检测,乙状结肠镜,CT肠镜(VirtualColonoscopy),常规大肠镜。以下将逐一简单予以介绍。

1.
大便潜血检查。

分普通方法和近年来推荐的免疫学方法,其区别在于后者能较特导性地检测出肠道出血,不受其他氧气剂影响,但是测不出是否为肠癌出血。这是唯一经过大型严格设计研究证明能够降低死亡率的有效方法。大肠癌出血后被检查出来应该不会是很早期的癌症。然而即使中晚期癌症被检查出来仍然可以明显降低死亡率说明大肠癌生长速度和转移速度是相当缓慢的,比胃癌和食管癌以及其他上消化道癌好太多了。

2. 
大便肠癌核酸检测论上应该可以检测出癌前期及早期肠癌,但实际操作上则不甚理想而且费用昂贵,如果不能解释这些问题,广泛临床使用的前景不会好。

3.
乙状结肠镜。

是一种短的结肠镜一般而言仅可以看到左侧结肠,绝大多数肠癌都在左侧,尤其在亚洲人群中乙状结肠镜无需麻醉,故费用低近年来研究也证实此方法可以降低肠癌死亡率。很多国家推荐乙状结肠镜加大便潜血检查来进行肠癌普查应是明智之举,便宜而且有效。

4. CT-
肠镜.

 就是CT 扫描的肠道造影术,价格上不便宜,有放射而且亦不太舒服无麻醉但肛门上需加一个管子持续充气,估计比全麻或半麻的常规肠镜都难受,发现了肿瘤则需要常规肠镜来切除。对肠癌发生危险性低又害怕侵入性肠镜的人或许有吸引力.

5. 
规肠镜可以检查整个大肠而且可以同时切除小的肿瘤,全麻或半麻状态下基本是无痛的,突出的优点是可以检查出右侧结肠的危害性大的扁平肿瘤但是这种肿瘤的发病率实在不太高肠癌是生长较慢的肿瘤,现在肠镜复查的频率有些太过频繁以至媒体抱怨将拖垮全民保健计划,绝大多数良性肿瘤都没有切除的必要肠镜的併发症包括肠穿孔,术后出血和死亡等,但其发生率应该是非常低的尤其是在胃肠科医师操作时,我本人做过数千例肠镜从末见到这些併发症.  然而常规肠镜对肠道和系膜的损伤是不可避免的,这也是为什么需要麻醉的原因。

6.
新技术:

欧洲尤其是德国使用一种一次性计算机辅助机动肠镜可以避免常规肠镜的缺点,无需麻醉且无交叉感染,这种肠镜己通过FDA 批准正在加州和纽约试用,我的诊所准备引进这种肠镜胶囊大肠镜在欧洲,日本以及以色列己用了数年,技术应该是相当成熟,正在等待FDA 批准,绝对方便和受欢迎,我期待用此方法为我自己做第一个肠镜.


第四名胰腺癌


胰腺的腺癌不是乔布斯得的胰腺神经内分泌肿瘤在各种肿瘤由于普查及早期治疗后死亡率逐步下降的今天,其死亡率却逆势增长成为所以肿瘤死亡率最高第四名.其原因在于难以早期发现。其危险因素包括肥胖,缺乏运动,糖尿病,吸烟喝酒,食用过多红肉,软饮料而缺少新鲜水果和蔬菜导致叶酸和维生素D缺乏,慢性胰腺炎,幽门螺旋杆菌感染,胆囊及胃手术,家族胰腺癌病史等等血清学检查和影像结合可能会发现早中期肿瘤,然而由于早中期肿瘤常无症状,做这些检查的可能性不大,因此常常错过机会.如果有以上多种危险因素,应及早纠正并找机会检查一下应该有帮助.


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叶医师信箱
1#发布于 2017-05-16 13:25:37
New Blood Test for colon Cancer

ColoVantage® (methylated Septin 9)
 
Clinical Use
Detect circulating methylated DNA from the SEPT9 gene
Aid in the detection of colorectal cancer (CRC) in patients non-adherent to current testing modalities
Clinical Background
Colorectal cancer (CRC) is the fourth most common cancer in the United States, however, it is the second leading cause of cancer-related deaths.1 The high number of deaths is likely due to the following facts:
The 5-year survival rate dramatically drops from about 90% for patients diagnosed with localized disease to 70% and 12% for those diagnosed with regional and distant stage disease, respectively.2
Only about 40% of patients are diagnosed at an early stage.1
Only about half of adults age 50 and over have been screened.3
Epigenetic changes, including methylation, play a role in the pathogenesis of CRC. Furthermore, DNA methylation occurs in the early stages of tumor development and can serve as a marker for precancerous lesions, such as adenomas. Circulating methylated DNA from the SEPT9 gene, which is involved in cytokinesis and cell cycle control, has been identified as such a marker.
The ColoVantage test detects methylated DNA from the SEPT9 gene in plasma. A case-control study performed at Quest Diagnostics showed that the ColoVantage test is 70% sensitive for CRC detection at a specificity of 89%.4 ColoVantage has successfully detected cancer at all stages; however, the number of patients at each stage of cancer was too small to derive stage-specific sensitivity data. A similar test demonstrated a sensitivity of 67% and a specificity of 88% in a prospective study of almost 8000 people.5
Current screening methods are either moderately invasive or require collection of a stool sample. Special patient preparation steps are often involved. These, among other things, may be barriers to screening.
ColoVantage represents an important medical advancement in that it is a plasma-based test that requires no patient preparation. A physician may order the ColoVantage test for screen-eligible patients who have previously avoided established colorectal cancer screening methods such as colonoscopy, fecal occult blood tests, and fecal immunochemical tests (FITs). A patient whose ColoVantage test result is positive may be at increased risk for colorectal cancer and further evaluation should be considered. ColoVantage is not a replacement test for colonoscopy.
Method
Real-time polymerase chain reaction (PCR)-based measurement of methylated SEPT9 DNA
Alias: methylated septin 9 DNA, methylated SEPT9 DNA
Interpretive Information
A patient whose ColoVantage test result is positive may be at increased risk for colorectal cancer and further evaluation should be considered.
References
American Cancer Society. Statistics for 2012. American Cancer Society Web site. Available at: http://www.cancer.org/Research/CancerFactsFigures/index. Accessed October 3, 2012.

Howlader N, Noone AM, Krapcho M, et al (eds). SEER Cancer Statistics Review, 1975-2009. National Cancer Institute SEER Web site. Available at: http://www.seer.cancer.gov/statfacts/html/colorect.html. Updated November 2011. Accessed October 3, 2012.

Shapiro JA, Seeff LC, Thompson TD, et al. Colorectal cancer test use from the 2005 national health interview survey. Cancer Epidemiol Biomarkers Prev. 2008;17:1623-1630.

Data on file at Quest Diagnostics.

Rösch T, Church T, Osborn N, et al. Prospective clinical validation of an assay for methylated SEPT9 DNA for colorectal cancer screening in plasma of average risk men and women over the age of 50 [abstract]. Gut. 2010;59(suppl III):A307.


This test was developed and performance characteristics have been determined by Quest Diagnostics Nichols Institute. Performance characteristics refer to the analytical performance of the test.
   
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