DDW 2009:軟式乙狀結腸鏡篩檢在7年時可略為降低癌症風險


  June 1, 2009(芝加哥) —根據發表於2009年消化症週、以及日前線上登載於英國醫學期刊(BMJ)期刊的「NORwegian Colorectal CAncer Prevention (NORCCAP)」試驗結果,以軟式乙狀結腸鏡篩檢大腸癌顯示出統計上並不顯著的大腸直腸癌死亡率降低,數值為27%。
  
  研究者表示,該發現認為,7年的追蹤期太短,而無法觀察到任何的大腸癌發生率降低。
  
  NORCCAP是一項族群基礎試驗,共有55,736名年紀在55至64歲的參與者,隨機分派接受軟式乙狀結腸鏡篩檢合併或未合併大便潛血檢查,或接受一般照護,而未進行大腸癌篩檢。
  
  這項進行中研究的主要終點是,5、10、15年時的大腸直腸癌發生率與死亡率。
  
  主要研究者、挪威Telemark醫院醫學教授Geir Hoff醫師,以及NORCCAP中心和奧斯陸的挪威癌症登記中心,在NORCCAP試驗中首次報告。
  
  Hoff醫師發表7年的累積大腸直腸癌發生率,以及6年之後的死亡率風險比。累積大腸直腸癌發生率為,篩檢組每100,000人-年有134.5例,未篩檢組每100,000人-年有131.9例。
  
  Hoff醫師在BMJ的新聞稿中表示,篩檢組與控制組之間,7年的累積大腸直腸癌發生率並無統計上的顯著差異。
  
  NORCCAP試驗的研究者發現,有大腸直腸癌死亡率降低的傾向,隨機分派接受篩檢者的死亡率減少27% (風險比[HR]為0.73;95%信心區間 [CI]為0.47 – 1.13;P = .16)。
  
  不過,就那些實際上接受軟式乙狀結腸鏡篩檢者而言,相較於控制組病患,整體大腸直腸癌有統計上的明顯減少,達59% (HR,0.41;95% CI,0.21 – 0.82;P = .011),正乙狀結腸癌減少76%(HR,0.24;95% CI,0.08 – 0.76;P = .016)。
  
  Hoff醫師警告,這類型病患的分析可能有取樣偏差。
  
  Hoff醫師表示,看來在7年時還無法證明篩檢是否降低大腸直腸癌的死亡。NORCCAP的研究者寫道,篩檢降低癌症的效果可能偏低,因而可能只是比預期的晚發生。
  
  Hoff醫師對軟式乙狀結腸鏡篩檢此意料外的效果偏低情況,提出兩個可能的解釋。其一,兩種方法對於降低大腸直腸癌都沒效,或者,其二,發現先驅病灶到發生癌症之間的期間比一般假定的還要更久。
  
  印地安拿波里、印第安那大學醫學中心醫學教授Thomas Imperiale醫師在BMJ的編輯評論中寫道,雖然兩組之間的差異並不顯著,我們對此一期中報告仍應感到鼓舞。
  
  Imperiale醫師表示,迄今的證據均強烈認為,以一次乙狀結腸鏡篩檢可以降低大腸直腸癌的發生率和死亡率,且被視為合法的策略。這效果的持續性與重要度則未被探討,在運用上還需要對不同族群的接受度、花費等進行努力。
  
  紐約市亞伯特愛因斯坦醫學院醫學教授、Montefiore醫學中心胃腸科主任Lawrence Brandt醫師表示,當你著眼於整體族群時,這些發現有其道理。
  
  Brandt醫師在Medscape Gastroenterology的訪問中表示,不過,他們只有使用乙狀結腸鏡篩檢大腸癌,而非大腸鏡。不過,聊勝於無。檢查整個大腸還是比較好。
  
  Brandt醫師表示,NORCCAP試驗的最重要發現是,實際上有篩檢者的大腸直腸癌死亡率顯著低於控制組病患,顯示出乙狀結腸鏡篩檢對此類病患的效果。
  
  NORCCAP試驗接受挪威癌症協會與挪威健康部的資助。Brandt醫師無相關利益衝突需宣告。
  
  2009年消化症週(DDW):摘要283。發表於2009年6月1日。
  

DDW 2009: Minimal Cancer Risk Reduction With Flexible Sigmoidoscopy Screening at 7 Years

By Martha Kerr
Medscape Medical News

June 1, 2009 (Chicago, Illinois) — Flexible sigmoidoscopy screening for colon cancer showed a statistically nonsignificant reduction in colorectal cancer mortality of 27%, according to findings of the NORwegian Colorectal CAncer Prevention (NORCCAP) trial, presented here today during Digestive Disease Week 2009 and published online yesterday in the British Medical Journal (BMJ).

The findings suggest that 7 years of follow-up is too short a period to observe any reduction in colon cancer incidence, the researchers say.

NORCCAP is a population-based trial of 55,736 people aged 55 to 64 years randomized to flexible sigmoidoscopy screening with or without fecal occult blood testing or to "usual care," with no colon cancer screening.

The primary endpoints of the ongoing study are incidence and mortality of colorectal cancer at 5, 10, and 15 years.

This first report from NORCCAP was presented here by principal investigator Geir Hoff, MD, professor of medicine at Telemark Hospital in Skien, Norway, and with the NORCCAP Center and the Cancer Registry of Norway in Oslo.

Dr. Hoff presented the 7-year cumulative incidence of colorectal cancer and the hazard ratio for mortality after 6 years.

The cumulative incidence of colorectal cancer was 134.5 cases per 100,000 person-years in the screened group and 131.9 cases per 100,000 person-years in the unscreened group.

"No [statistically significant] difference was found in the 7-year cumulative incidence of colorectal cancer between the screening and control groups," Dr. Hoff said in a BMJ news release.

The NORCCAP investigators found a "trend toward reduced colorectal cancer mortality," with a reduction of 27% among all individuals randomized to screening (hazard ratio [HR], 0.73; 95% confidence interval [CI], 0.47 – 1.13; P = .16).

However, for attenders (those randomized to screening who actually underwent flexible sigmoidoscopy) compared with control patients, there was a statistically significant 59% reduction in both total colorectal cancer (HR, 0.41; 95% CI, 0.21 – 0.82; P = .011) and a 76% reduction in rectosigmoidal cancer (HR, 0.24; 95% CI, 0.08 – 0.76; P = .016).

Dr. Hoff cautioned that analysis of attenders "is prone to selection bias."

It appears that 7 years is "...too early to say whether screening reduces deaths from colorectal cancer," Dr. Hoff said. "The cancer-reducing effect of screening may be lower and will certainly occur later than anticipated," the NORCCAP investigators write.

Dr. Hoff offered 2 possible explanations for the unexpectedly small effect of flexible sigmoidoscopy screening. First, "...either the method is not effective in reducing colorectal cancer..." or second, "...the lag period for the development of cancer from precursor lesions is considerably longer than is commonly assumed," he said.

"Although the difference between the groups was not significant, we should be encouraged by this study's interim findings," writes Thomas Imperiale, MD, professor of medicine at Indiana University Medical Center in Indianapolis, in an accompanying editorial in the BMJ.

"Evidence to date strongly suggests that one time screening sigmoidoscopy can reduce incidence and mortality from colorectal cancer and may be a legitimate strategy," Dr. Imperiale said. "The magnitude and duration of benefit have yet to be ascertained, along with acceptability in different populations and the effort and cost needed for implementation."

"These findings make sense, when you look at the population as a whole," Lawrence Brandt, MD, chief of the Division of Gastroenterology at Montefiore Medical Center and professor of medicine at the Albert Einstein College of Medicine in New York City.

"However, they only used sigmoidoscopy for colon cancer screening, rather than colonoscopy... But half a loaf is better than none," Dr. Brandt commented in an interview with Medscape Gastroenterology. "It is always better to look at the whole colon."

The NORCCAP trial's most important finding is where they found that "individuals actually screened had significantly lower risk of dying from colorectal cancer compared to controls, indicating an effect of flexible sigmoidoscopy screening in those attending,'" Dr. Brandt said.

NORCCAP was funded by grants from the Norwegian Cancer Society and the Norwegian Ministry of Health. Dr. Brandt had no relevant conflicts of interest to declare.

Digestive Disease Week (DDW) 2009: Abstract 283. Presented June 1, 2009.

BMJ. 2009;338:b1846, b2084. Study Abstract, Editorial

    
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