斷層掃描改善肺癌病患預後


  May 12, 2009 — 根據一項發表在5月號胸腔腫瘤學期刊的研究報告指出,斷層掃描(CT)可能可以偵測早期肺癌,且改善肺癌病患預後。
  
  在這項回溯性研究中,來自日本東京國家癌症中心醫院的研究團隊發現,篩檢偵測到的肺癌患者,預後比意外或是因為他們有症狀才發現的好。篩檢組的肺癌在特徵上比較不具侵襲性、比較小、且比較常被診斷為腺瘤。
  
  當以不同的裝置偵測時,接受CT掃描的病患,其五年存活率比用X射線攝影、正子攝影(PET)或是痰液病理學檢驗的高。不同偵測裝置檢測到的存活率差異達到統計顯著差異(P=0.0127)。
  
  肺癌是日本癌症死亡最常見的原因,研究團隊表示,早期診斷與手術切除仍然是治癒可能性最高的方法。過去針對重度吸菸患者使用胸部X射線攝影與痰液細胞學檢驗的研究,並未證實可以降低肺癌相關死亡率,但是最近,許多研究顯示這項疾病可以在比較早期時偵測。
  
  【仍有爭議】
  肺癌篩檢的效果仍然是有爭議的,作者寫到,目前並沒有指引建議進行篩檢。尤其使用CT篩檢的證據仍是有爭議的,如同過去Medscape腫瘤學所報告的。
  
  國際初期肺癌行動計劃(I-ELCAP)的數據,2006年10月時於新英格蘭醫學期刊上報告(2006; 355: 1763-71),媒體也廣泛報導。研究團隊宣稱,以CT掃描對高風險族群進行早期診斷,可以預防近80%因為肺癌而死亡。
  
  然而,這項研究被廣泛討論,且一項發表在美國醫學會期刊(JAMA. 2007; 297: 953-61.)駁斥了CT篩檢可以改善預後的論點。
  
  當時許多專家表示,直到進行中的大型研究完成之前,目前並沒有類似的建議,就如同Medscape腫瘤學所報導的。
  
  目前這項由Hisao Asamura醫師與其同事進行的回溯性分析,作者們強調,他們太過於強調等待前瞻性研究的數據。他們寫到,為了直接展示肺癌篩檢的作用,我們必須等到進行中的隨機分派研究結果公佈,例如荷蘭路文篩檢Onderzoek歐洲研究與國家肺癌篩檢北美研究。
  
  在他們的研究中,Asamura醫師與其同事企圖找出透過篩檢檢測到肺癌的特徵,以及找出篩檢偵測出疾病的病患,預後是不是比那些意外發現或是有症狀病患好。
  
  這項回溯性研究回溯了2,281位在2000年到2006年於東京國家癌症中心接受肺切除手術病患的病歷,根據偵測的方法,這些病患被分為三組,,分別為篩檢偵測(共1,290位)、症狀偵測(共481位)以及意外發現(共568位)。在篩檢偵測組中,研究團隊分析臨床病理因子,依篩檢方式不同分為:X射線攝影(共1,136位,佔82.6%)、斷層掃描(共196位,佔13.9%)、正子攝影(共22位,佔1.6%)、痰液病理學檢驗(共17位,佔1.3%)。
  
  【篩檢偵測癌症能改善存活率】
  評估篩檢偵測肺癌的特性,研究者發現,比起其他偵測方法,其腫瘤的直徑都較小(小於2公分,佔42.6%),較不具侵襲性(病理分級第一級,佔70.8%)以及有較高腺癌的發生率(佔85.8%)。有類似的傾向發生在意外發現組,但病患有症狀者都有較大的腫瘤且很多都具侵襲性。如以電腦斷層方式篩檢偵測肺癌,相較於胸部X光或PET篩檢,腫瘤的直徑都較小(小於2公分,佔76.4%),較不具侵襲性(臨床分級第一級,佔97.2%;病理分級第一級,佔93.1%)以及有較高腺癌的發生率(佔92.6%)。
  
  研究團隊也發現,以診斷方式進行分期,5年存活率有明顯差異。整體而言,2,281位病患的5年存活率是75.4%,且1,486位為病理分級第一期的非小細胞肺癌。
  
  【根據篩檢方式不同的5年存活率】

篩檢方法

5 年存活率

篩檢偵測

79.6%

症狀偵測

74/6%

意外發現

64.6%


  三組達到統計上顯著差異。其中疾病分級第一級的整體存活率為89.6%。5年存活率在篩檢偵測組為92.9%,症狀偵測組為84.0%,意外發現組為84.6%。篩檢偵測組的5年存活率也因篩檢方式不同而有異,其中電腦斷層是最高的。
  
  【篩檢偵測組根據不同偵測方法的5年存活率】

偵測方法

5 年存活率

電腦斷層

91.2%

胸部 X 光

77.8%

正子攝影

90.9%

痰液病理學檢驗

80.9%


  在篩檢偵測組中,有896位病患被診斷出第一級非小細胞肺癌,在本世代研究中,電腦斷層篩檢病患的5年存活率為91.7%,胸部X光則為81.4%。
  
  研究作者表示沒有相關的資金往來。
  

CT Scanning Improves Survival in Lung Cancer

By Roxanne Nelson
Medscape Medical News

May 12, 2009 — Screening computed tomography (CT) might be able to detect early-stage lung cancers and improve the prognosis of lung cancer patients, according to a study published in the May issue of the Journal of Thoracic Oncology.

In this retrospective study, researchers from the National Cancer Center Hospital in Tokyo, Japan, found that patients with screen-detected lung cancer had better survival than patients whose cancers were identified either incidentally or because they had become symptomatic. The lung cancers in the screened group were characteristically less advanced, had a smaller diameter, and were more frequently diagnosed as adenocarcinoma.

When looking at different modalities of detection, 5-year survival rates for patients screened by CT scan were higher than rates for patients screened by chest x-ray, positron emission tomography (PET), or sputum cytology. The difference in survival between the detection modalities was significant (P?= .0127).

Lung cancer is the most common cause of cancer death in Japan, the researchers note, and early detection and surgical resection continue to remain the best possibility for cure. Previous trials using chest x-ray and sputum cytology in heavy smokers have failed to show a reduction in lung-cancer-related mortality, but more recently, several studies have shown that the disease can be detected at a much earlier stage.

Continued Controversy

The efficacy of screening for lung cancers remains controversial, the authors write, and there are no guidelines that currently recommend screening. In particular, evidence for the use of CT scanning for lung cancer is conflicting, as previously reported by Medscape Oncology .

Data from the International Early Lung Cancer Action Project (I-ELCAP), reported in October 2006 in the New England Journal of Medicine (2006;355:1763-1771), were widely publicized in the lay media. The researchers claimed that CT scanning in high-risk populations could prevent about 80% of deaths from lung cancer by detecting the disease in its earliest stages.

However, that study was criticized, and subsequently, a large study published in the Journal of the American Medical Association (JAMA. 2007;297:953-961) refuted the claims that CT scanning improved survival.

At the time, many expert commentators said that no recommendations should be made until large ongoing trials were completed, as reported by Medscape Oncology .

The current study by Hisao Asamura, MD, and colleagues is a retrospective analysis, the authors emphasize, and they too stress the need to wait for data from prospective studies. "For a direct demonstration of the effectiveness of lung cancer screening, we must wait for the results from ongoing randomized control trials, such as the Nederlands Leuvens Screening Onderzoek trial in Europe and the National Lung Screening Trial in North America," they write.

In their study, Dr. Asamura and colleagues attempted to identify the characteristics of lung cancer detected by screening, and to clarify whether patients with screen-detected disease had better survival than those with incidental or symptomatic cancers.

They retrospectively reviewed the records of 2281 patients who underwent lung cancer resection surgery between 2000 and 2006 at the National Cancer Center in Tokyo. Patients were classified into 3 groups, according to the method of detection: screen detected (n?= 1290), symptom detected (n?= 481), and incidental (n?= 568). In the screen-detected group, the researchers analyzed clinicopathological factors according to screening modality used: chest x-ray (n?=1136; 82.6%), CT (n?= 196; 13.9%), PET (n?= 22; 1.6%), and sputum cytology (n?= 17; 1.3%).

Improved Survival for Screen-Detected Cancers

When evaluating the characteristics of screen-detected lung cancers, the researchers observed that they were smaller in diameter (<2?cm, 42.6%), less advanced (pathologic stage?I, 70.8%) and showed a higher incidence of adenocarcinoma (85.8%) than those detected by the other methods. Similar tendencies were seen in incidentally detected lung cancers, but patients with symptomatic disease had larger tumors and they were more advanced.

Of screen-detected disease, cancers identified by CT scanning — compared with those identified by chest x-ray or PET-scan — were smaller in diameter (<2?cm, 76.4%), less advanced (clinical stage?I, 97.2%; pathologic stage?I, 93.1%), and more were frequently diagnosed as adenocarcinoma (92.6%).

The team also found that after classifying patients on the basis of diagnostic modality, there was a marked difference in 5-year survival rates. Overall, the 5-year survival rate for the 2281 patients was 75.4%, and 1486 had pathologic stage?I nonsmall-cell lung cancer.

5-Year Survival According to Detection Method
Type of Detection 5-Year Survival Rate
Screen-detected 79.6%
Symptomatic 74/6%
Incidental 64.6%

?

The differences between the 3 groups were statistically significant. In the subgroup with stage?I disease, overall survival was 89.6%. Five-year survival rate for screen-detected patients was 92.9%, for symptomatic disease was 84.0%, and for incidental detection was 84.6%.

The 5-year survival rates also differed among screen-detected cases according to the modality used, with CT showing the highest rates.

5-Year Survival of Screen-Detected Lung Cancer According to Modality

Modality 5-Year Survival Rate
CT 91.2%
Chest x-ray 77.8%
PET 90.9%
Sputum cytology 80.9%
    
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