Oioe

作者：Roxanne Nelson  
出處：WebMD醫學新聞

　　April 13, 2010 — 大腸鏡檢查已經被確定是一種有效的大腸直腸癌篩檢方法，現在，一篇研究發現它和減少疾病相關死亡率有關。
　　
　　這篇線上發表於3月2日美國腸胃科期刊(American Journal of Gastroenterology)的研究中，研究者發現，大腸鏡檢查完成率每增加1%，大腸直腸癌相關死亡風險減少3%。
　　
　　第一作者、安大略多倫多大學醫學教授Linda Rabeneck醫師表示，我們發現，居住在大腸鏡檢查比率較高的區域，和大腸直腸癌死亡風險減少有關。
　　
　　她向Medscape Oncology表示，我們研究中所提的大腸鏡檢查不只是用來篩檢，也有用於診斷，整體而言，我們可以說，大腸鏡使用程度增加有其助益。
　　
　　不過，一名受邀發表獨立評論的專家提出警告，認為必須謹慎詮釋這些發現。印第安那大學醫學院臨床醫學助理教授Charles Kahi醫師表示，大腸鏡檢查率增加和大腸直腸癌死亡率減少有關，但是，這並未能解釋兩者之間的因果關係。
　　
　　【大腸鏡檢查是黃金標準】
　　作者們指出，大腸鏡檢查變成偵測和移除腺瘤的黃金標準，大腸鏡息肉切除術和大腸直腸癌發生率減少有關，在過去廿年，美國和加拿大使用大腸鏡檢查的情形增加，但是依舊不清楚增加使用和人們的臨床助益是否有關。
　　
　　這是Rabeneck醫師等人試圖解答的問題，他們使用加拿大健康資訊研究中心出院摘要與同日手術資料庫、安大略健康保險計畫資料庫、登記個人資料庫、以及安大略癌症登記等的人口資料。
　　
　　在1993年1月1日共辨識2,412,077名年紀介於50-90歲的研究對象，每個人根據居住地被分派到13個區域之一，所有研究對象被追蹤到2006年12月31日，每年計算每個區域內此一年齡層人口進行大腸鏡檢查的比率。作者們使用多變項Cox比例風險模式評估大腸鏡檢查比率和大腸直腸癌相關死亡的關聯，校正年紀、性別、共病症、收入、居住位置(都市或鄉村)等干擾因素。
　　
　　研究對象的平均年紀為64歲，幾乎半數(53.7%)是女性，在這14年追蹤期間，62,819名研究對象(2.6 %)診斷有大腸直腸癌，23,743人(0.98%)死於該症，整個世代中，773,677人(32.1 %)死亡。
　　
　　【檢查比率增加、死亡率減少】
　　從1993-2006年，各區域的大腸鏡檢查比率增加，研究者指出，增加比率和大腸直腸癌相關死亡成反比，風險比0.970 (95 %信心區間為0.949- 0.991)，意味著該區域的大腸鏡檢查比率每增加1%，死亡風險減少3%。
　　
　　比較年輕者(50-69歲)的大腸直腸癌相關死亡較低，在每個年齡層中，女性的比率都比男性低。研究者也發現，年紀增加、收入較低、居住於鄉村等與大腸直腸癌死亡風險較高有關；女性與風險較低有關。校正這些干擾因素之後，完成大腸鏡檢查比率增加仍與大腸直腸癌相關死亡風險減少有關。
　　
　　Rabeneck醫師指出，有許多介入方式可以增加篩檢比率，最重要的是，一線照護者或家庭醫師的建議，不只大腸直腸癌篩檢如此，其他癌症篩檢也是。
　　
　　她指出，除去缺乏保險這類阻礙也很重要，另外可藉助社會行銷或公共提醒活動，如同乳癌防治一樣，乳癌篩檢比率高於大腸直腸癌篩檢，對於大腸直腸癌篩檢，我們還沒有達到這麼高的公共警覺。
　　
　　【需仔細詮釋研究發現】
　　Kahi醫師受Medscape Oncology之邀發表獨立評論時表示，雖然這個研究做得不錯，但是對研究結果的詮釋必須謹慎，勿超出研究範圍。
　　
　　他總結表示，這是一個大範圍流行病學研究，作者們發現，人口基礎之大腸鏡檢查使用增加與大腸直腸癌死亡率減少有關。
　　
　　Kahi醫師表示，不過，有一些議題對於確認結論有所限制，第一，這是一個大範圍流行病學研究，它通常難以將這些研究發現轉成個別病患的臨床決策，甚至無法和小規模的臨床研究結果相比。
　　
　　Kahi醫師指出，其次，「有關聯」這個發現不意味著因果關係，換句話說，大腸鏡檢查使用增加與減少死亡率有關，但是這些趨勢可能是平行的，而大腸鏡檢查使用增加和大腸直腸癌死亡率實際減少之間並無必要關係。
　　
　　最後，因為這個研究是根據管理資料，作者們無法區分哪些診斷是用大腸鏡檢查，所以，不清楚觀察到的這個關聯是否是因為篩檢本身的幫助所致。
　　
　　該研究並未接受外部資金，研究者皆宣告沒有相關財務關係。
　　
　　Am J Gastroenterol. 線上發表2010於年3月2日。


Colonoscopy Associated With Decrease in Colorectal-Cancer-Related Death

By Roxanne Nelson
Medscape Medical News

April 13, 2010 — Colonoscopy has been established as an effective method of screening for colorectal cancer, and now a study has found that it is associated with a reduction in disease-related mortality.

In the study, published online March?2 in the American Journal of Gastroenterology, researchers found that for every 1% increase in the complete colonoscopy rate, the hazard of colorectal-cancer-associated death decreased by 3%.

"We found that living in a region with higher colonoscopy rates was associated with a reduced risk of death from colorectal cancer," said lead author Linda Rabeneck, MD, MPH, professor of medicine at the University of Toronto in Ontario.

"The colonoscopies in our study were not only done for screening, but for other reasons, such as diagnosis," she told Medscape Oncology. "Overall, we can say at a population level that the increase in colonoscopy use has been associated with a benefit."

However, an expert contacted for independent comment cautioned that the findings need to be interpreted with care. There was an association between an increased colonoscopy rate and a decreased colorectal cancer mortality rate, but this does not necessarily mean that one was the result of the other, said Charles Kahi, MD, assistant professor of clinical medicine at Indiana University School of Medicine in Indianapolis.

Colonoscopy Is the Gold Standard

Colonoscopy has become the gold standard for detecting and removing adenomas, the authors note, and colonoscopic polypectomy is associated with a decrease in the incidence of colorectal cancer. The use of colonoscopy in the United States and Canada has increased during the past 2 decades, but it remains unclear whether increased use is associated with clinical benefits at the population level.

This was the question that Dr. Rabeneck and colleagues wanted to answer. They used population data from the Canadian Institute for Health Information discharge abstract and same-day surgery databases, the Ontario Health Insurance Plan database, the Registered Persons Database, and the Ontario Cancer Registry.

A cohort of 2,412,077 people between the ages of 50 and 90 years on January?1, 1993 was identified. Each person was assigned to 1 of 13 regions, based on his/her residence, and all participants were followed until December?31, 2006. Every year for each region, the rate of colonoscopies performed on people within this age group was calculated. The authors used the multivariable Cox proportional hazards models to evaluate the association between colonoscopy rate and colorectal-cancer-associated death, adjusting for confounders such as age, sex, comorbidity, income, and location of residence (urban vs rural).

The mean age of the participants was 64 years, and approximately half (53.7%) were female. During the 14-year follow-up, 62,819 study participants (2.6 %) were diagnosed with colorectal cancer, and 23,743 (0.98%) died from the disease. Of the entire cohort, 773,677 (32.1 %) participants died from all causes.

Rates Increased, Mortality Declined

From 1993 to 2006, rates of colonoscopy increased in all regions, and the researchers noted that this increased rate was inversely associated with colorectal-cancer-related deaths. The hazard ratio of 0.970 (95 % confidence interval, 0.949?- 0.991) indicated that for every increase in colonoscopy rate of 1% in the region the participant resided, the hazard of death decreased by 3%.

Colorectal-related mortality was lower among younger adults (50 to 69 years), and within each age group, the rates were lower for women than for men. The researchers also found that increased age, lower income, and a rural residence were associated with a higher risk for death from colorectal cancer; being female was associated with a lower risk. After adjustment for these confounders, an increased complete colonoscopy rate was still associated with a decreased risk for colorectal-cancer-associated mortality.

There are several interventions that have been shown to increase screening rates, Dr. Rabeneck pointed out. "One of the most important is the recommendation of the primary care provider or family physician. This is true not just for colorectal cancer screening, but for other cancer screenings as well," she said.

Removing barriers, such as lack of insurance, is important, as is having a social marketing or public awareness campaign, she added. "That is part of the reason breast cancer screening rates are higher than rates of colorectal cancer screening," she said. "For colorectal [cancer screening], we have not yet achieved such a high level of public awareness."

Findings Need Careful Interpretation

Although this is a very nicely done study by an expert group, the findings have to be interpreted within the context of the study, said Dr. Kahi, who was approached by Medscape Oncology for independent comment.

"This is a large-scale epidemiological study, and the authors found that increased colonoscopy use was associated with decreased colorectal mortality at the population level," he summarized.

However, there are some issues that preclude making additional valid conclusions, said Dr. Kahi. "First, this is a large-scale epidemiological study, and it is often hard to translate the findings of such studies into clinical decisions for individual patients, or even to compare the results with those of clinical smaller-scale studies," he noted.

Second, the finding of an "association" does not imply causality. "In other words, increased colonoscopy use is associated with decreased mortality, but these trends may be evolving in parallel, and it does not follow necessarily that increased colonoscopy use actually caused the drop in colorectal cancer mortality," Dr. Kahi added.

"Finally, given that the study is based on administrative claims, the authors could not distinguish screening from diagnostic colonoscopy, so it is not clear if the observed association is due to the benefit of screening itself," he said.

The study received no outside funding. The researchers have disclosed no relevant financial relationships.

Am J Gastroenterol. Published online March?2, 2010.