疏漏的大腸直腸癌一般是因外觀難以發現導致


  【24drs.com】間隙大腸直腸癌(CRCs)的發生原因還不清楚,但是,荷蘭的一篇研究確認這類病灶有著肉眼難以發現的小而平的外觀,因此容易在大腸鏡檢查追蹤時被疏漏。
  
  荷蘭馬斯垂克大學醫學中心的醫學生Chantal le Clercq在2011年消化道疾病週(DDW)的「DDW最佳論文(Best of DDW)」小組中發表這篇歷時10年的案例回顧結果;Silvia Sanduleanu博士則是該篇研究的資深研究者。
  
  她發現大部分的間隙型癌症與被忽略的病灶有關,或許是因為它們又小又平,小到未被大腸鏡息肉切除術完整移除;這意味著,亟需在臨床實務加強預防這類間隙型CRCs的檢查和治療的完整訓練。
  
  印第安那大學醫學院醫學特聘教授、美國胃腸道協會前任理事長Douglas Rex醫師在獲邀發表有關大腸鏡檢查的演講時回應這些論述,形容大腸鏡檢查是醫學訓練中最重要的,需善用大腸鏡檢查並精進此項技術。
  
  這篇研究中,間隙型CRC被定義為在一次指定的大腸鏡檢查後6個月至5年間發現者,在其他研究中,發生率佔所有CRCs的5%-8%,她表示,間隙型癌症比原本所認知的更常見,相關因素包括手術者相關變項以及治療無效,但是實際原因未知。
  
  為了深入瞭解這個議題,研究者回顧了2001至2010年間在馬斯垂克大學醫學中心診斷有CRC的所有病患的資料,排除遺傳性CRC、發炎性腸道疾病、之前的CRC病史;研究者評估了肉眼可見的外觀— 特別是比較平坦和突出這兩類,以及探討大腸的癌症病灶位置,他們也和之前診斷出的非間隙型CRC比較了這些特徵。
  
  間隙型CRC被分類為漏失病灶(有難以發現的外觀),可能是因為大腸鏡息肉切除術不完整(病灶發生在前次大腸鏡息肉切除術的相同片段)或者不明原因。
  
  診斷有CRC的1,218名病患中,39人(3.1%)在5年內進行大腸鏡檢查,其中11名病患被排除,因為看不清楚或未適當監測,剩下28名病患,間隙型CRC比率為2.2%;病患的平均年紀是73歲,71%是男性,大腸鏡檢查後的平均時間是26個月,多數病患是因為有症狀才進行大腸鏡檢查。
  
  le Clercq小姐報告指出,相較於非間隙型癌症,間隙型CRC的大小確實比較小,且這些病灶比較平。
  
  小於1公分的病灶在間隙型CRC的比率有11.6%,非間隙型則是有1.3%,而1到2公分的病灶比率則分別是19.2%和12.5%,大於2公分的癌症比率則分別是69.2%和86.2%(P < .001),間隙型病灶和非間隙型病灶的平均大小分別是2.7公分和3.9公分。
  
  平坦病灶比率在間隙型CRC為48.1%、非間隙型則是20.9%,突出型比率則分別是51.9%和79.1%(P < .001)。
  
  其他特徵則都相似,包括分期(早期與末期)、組織學(分化不全或分化完全)以及提供者的專科(約75%是胃腸科醫師)。
  
  至於位置,病灶位置在近端大腸的比率分別是間隙型案例的70.4%與非間隙型的32.9% (P < .001)。
  
  校正年紀和性別的回歸分析中,勝算比如下:
  * 小病灶:勝算比為0.82 (P = .020)
  * 平坦與突出外觀的比較:勝算比3.75 (P = .001),且
  * 近端與遠端的比較:勝算比5.07 (P < .001)。
  
  她結論指出,難以發現的外觀可解釋53.6%的CRC案例,這些可分類為「漏失的病灶」,有10.7%是在相同的片段,因此可能是未被完整移除,其他35.7%則無明確解釋。
  
  Sanduleanu博士的醫學中心目前聚焦在大腸鏡檢查對小且平之病灶的偵測訓練;她表示,我們將檢視這個有良好訓練團隊的間隙型癌症比率,研究者也計畫對間隙型病灶進行分子檢測,以評估這些是否代表著更具侵犯性的新癌症。
  
  Rex醫師在演講中指出,有些被忽略的癌細胞快速生長,這些可能包括鋸齒狀病灶,大部分是和BRAF突變有關,有著難以發現的外觀,且會迅速惡化;他認為,鋸齒狀病灶比腺瘤更容易被忽略,執業醫師的鋸齒狀病灶偵測率差異達7-18倍。
  
  他表示,內視鏡醫師必須能注意這些,發現並有效移除這類病灶;發現扁平腺瘤、為右側大腸提供更好的保護,這些都是需要改善之處。
  
  至於對荷蘭這篇研究發現的評論,他指出,這個研究團隊的大腸鏡檢查表現似乎是相當好,因為他們的間隙型CRC比率只有2.2%,低於之前的報告;這或許是因為他們是在大腸鏡檢查後6個月內發現癌症,而不像其他團隊是在6個月之後而比率較高。
  
  他也表示,大腸鏡息肉切除術不完整的11%比率實際上可能包括一些疏漏的癌症,因為同一片段可能有其他病灶,也可能是在下一個皺摺而未被發現,因而造成高比率的疏漏癌症,我們只是假設息肉未被完整移除,但是這些幾乎都是被忽視的病灶。
  
  資料來源:

Missed Colorectal Cancers Usually Have Subtle Appearance

By Caroline Helwick
Medscape Medical News

June 10, 2011 (Chicago, Illinois) — Reasons for the occurrence of interval colorectal cancers (CRCs) have been unclear, but a study from the Netherlands establishes that most such lesions have a subtle macroscopic appearance, in that they are primarily small and flat, and are easy to miss on follow-up colonoscopy.<;/p>; <;p>;The findings from a 10-year review of cases were presented in a "Best of DDW" session here at Digestive Disease Week (DDW) 2011 by Chantal le Clercq, a medical student at Maastricht University Medical Center in the Netherlands. The senior investigator was Silvia Sanduleanu, MD, PhD.<;/p>; <;p>;"We found that the majority of interval cancers could be related to lesions that were overlooked, probably because they were small or flat, and — to a lesser degree — incomplete polypectomy," she said. "This means that systematic training on detection and effective treatment is essential [for] preventing these interval CRCs in everyday practice."<;/p>; <;p>;Douglas Rex, MD, distinguished professor of medicine at Indiana University School of Medicine, Indianapolis, and a past president of the American Gastroenterological Association, echoed these remarks in an invited lecture on colonoscopy. He called colonoscopy "the most important procedure we teach in fellowship. Let's embrace colonoscopy and perfect it," he said.<;/p>; <;p>; <;b>;Interval Cancers Common<;/b>; <;/p>; <;p>;In this study, interval CRCs were defined as those detected between 6 months and 5 years after an index colonoscopy. Their incidence in other studies has been reported to range from around 5% to as high as 8% among all CRCs. "Interval cancers appear to be more common than we previously expected," she said. "Factors thought to be associated with them are operator-dependent variability and ineffectiveness of treatment, but the precise reasons are unclear."<;/p>; <;p>;To gain insight into this issue, the investigators reviewed data from all patients diagnosed with CRC at Maastricht University Medical Center between 2001 and 2010, excluding those with hereditary CRC, inflammatory bowel disease, and previous history of CRC. The researchers evaluated the macroscopic appearance — specifically, flat vs protruded — and location of the cancers in the colon, and they compared these characteristics with those of the previously diagnosed (noninterval) CRCs.<;/p>; <;p>;The interval CRCs were classified as being missed lesions (having a subtle appearance) either because of incomplete polypectomy (when the lesion occurred in the same segment as the previous polypectomy) or of unknown cause.<;/p>; <;p>;Of 1218 patients diagnosed with CRC, 39 (3.1%) had undergone colonoscopy within 5 years. Eleven of these patients were excluded because of incomplete visualization or inadequate surveillance, leaving 28 patients and yielding an interval CRC rate of 2.2%. Patients' mean age was 73 years, 71% were men, and their mean time from colonoscopy was 26 months. Most of the patients presented for colonoscopy because they had symptoms.<;/p>; <;p>; <;b>;Why Lesions May Have Been Missed<;/b>; <;/p>; <;p>;"The size of the interval CRCs, compared with the noninterval index cancers, was considerably smaller, and the lesions were more likely to be flat," Ms. le Clercq reported.<;/p>; <;p>;Lesions smaller than 1 cm were noted in 11.6% of interval CRCs vs 1.3% of noninterval cancers, and lesions 1 to 2 cm in size were seen in 19.2% vs 12.5%, respectively. Cancers larger than 2 cm occurred in 69.2% vs 86.2%, respectively (<;em>;P<;/em>; <; .001). The mean size of the interval lesions was 2.7 cm vs 3.9 cm for the noninterval lesions.<;/p>; <;p>;The appearance was flat in 48.1% of the interval CRCs vs 20.9% of the noninterval cancers, and protruded in 51.9% vs 79.1%, respectively (<;em>;P<;/em>; <; .001).<;/p>; <;p>;Other characteristics were similar, including stage (early vs advanced), histology (poor vs well-differentiated), and specialty of provider (approximately 75% were gastroenterologists).<;/p>; <;p>;By location, the lesions were found in the proximal colon in 70.4% of the interval cases vs 32.9% of the noninterval cases (<;em>;P<;/em>; <; .001).<;/p>; <;p>;In a regression analysis, adjusted for age and sex, the odds ratios were as follows:<;/p>; <;ul>; <;li>;small lesion: odds ratio, 0.82 (<;em>;P<;/em>; = .020),<;/li>; <;li>;flat vs protruded appearance: odds ratio, 3.75 (<;em>;P<;/em>; = .001), and<;/li>; <;li>;proximal vs distal location: odds ratio, 5.07 (<;em>;P<;/em>; <; .001).<;/li>; <;/ul>; <;p>;"A subtle appearance explained 53.6% of the CRCs, and these could be classified as 'missed' lesions, while 10.7% were in the same segment, and therefore may have been incompletely removed. For 35.7%, we found no clear explanation," she concluded.<;/p>; <;p>; <;b>;Could Missed Lesions Be More Aggressive?<;/b>; <;/p>; <;p>;Dr. Sanduleanu's center is now focusing colonoscopy training on the detection of small and flat lesions. "We will be looking at the future interval cancer rate in this well-trained group," she said. The investigators also plan to do molecular testing on interval lesions to assess whether these might represent inherently more aggressive, new cancers.<;/p>; <;p>;Dr. Rex, in his lecture, noted that some missed cancers may be fast-growing. These would include serrated lesions, many of which are associated with BRAF mutations and can have a subtle appearance, but can rapidly progress. "We may miss serrated lesions more than adenomas," he suggested. Detection rates of serrated lesions have been reported to vary 7- to 18-fold among practitioners, he added.<;/p>; <;p>;"It is important for the endoscopist to develop an eye for these in order to detect and remove them effectively," he said. Detection of depressed adenomas and providing greater protection to the right colon are also areas that need improvement.<;/p>; <;p>;Commenting on the Dutch findings, he noted that the group's performance of colonoscopy seemed to be "quite good," as their rate of interval CRCs was just 2.2%, which is lower than previous reports. Had they included cancers detected within 6 months of the colonoscopy, not after 6 months, as some groups do, the rate might have been higher, he suggested.<;/p>; <;p>;He also said the 11% rate of incomplete polypectomies may actually include some missed cancers. "You are getting the maximum rate of missed cancers, because it is possible another lesion was in the same segment, maybe the next fold over, and you missed it. You are just assuming the polyp was removed incompletely, but almost certainly some of those were missed lesions."<;/p>; <;p>; <;em>;Ms. le Clercq has disclosed no relevant financial relationships. Dr. Rex reported receiving consulting, speaking, and teaching fees for numerous pharmaceutical and device companies, and serving on several review boards.<;/em>; <;/p>; <;p>;Digestive Disease Week (DDW) 2011: Abstract 621r. Presented May 9, 2011.<;/p>;

    
相關報導
體適能較佳與某些癌症及死亡風險較低有關
2015/4/15 上午 10:28:31
紅肉與癌症:還有未知機轉?
2015/1/15 上午 10:19:15
年長者進行大腸癌篩檢具有成本效益
2014/6/5 上午 11:34:41

上一頁
   1   2   3   4   5   6   7   8   9   10  




回上一頁