PET-CT用於術前肺癌更佳


  July 1, 2009 — 根據一篇新研究,相較於非小細胞肺癌(NSCLC)的傳統分期,併用正子放射斷層造影術與電腦斷層(PET-CT)可以降低無效的胸廓切開術頻率。
  
  PET-CT也比傳統分期降低整體胸廓切開術的次數,改善診斷準確度。
  
  不過,作者寫道,這個在病患分期上更昂貴的技術並未顯著影響整體存活。本研究登載於7月2日的新英格蘭醫學期刊。
  
  雖然如此,研究作者強調,PET-CT的好處包括改善診斷準確度,可以幫助避免切除良性結節,避免根除性手術之後的早期局部與遠端復發。領銜作者為丹麥哥本哈根Odense大學醫院腫瘤科的Barbara Fischer博士。
  
  作者們認為,該研究的主要終點、無效的胸廓切開術,是一個有爭議、迄今在這領域中仍無一致認同的定義。在本研究中,被視為無效的胸廓切開術包括以下任一狀況:良性的肺部病灶、病理證實包括縱膈腔淋巴結(第IIIA [N2]期)、第IIIB或第IV 期疾病、無法手術的T3或T4疾病、隨機分組後一年內疾病復發或任何原因之死亡。
  
  作者們寫道,如果此定義被接受,無效的胸廓切開術可考慮作為有效的終點,傳統分期組比PET-CT組顯著較高的早期死亡與復發數,並非純屬偶然或PET-CT組有較成功的手術,而是反應出PET-CT組對適合手術之病患有較佳的篩選。
  
  特別的是,分期之後,PET-CT組的98人中有60名病患、傳統分期組的91人中有73人,被視為有可進行手術的疾病且接受胸廓切開術。
  
  PET-CT組的60名病患中,21人(35%)的胸廓切開術無效,傳統分期組的73人中,38人(52%)的胸廓切開術無效(P = .05)。
  
  在PET-CT組中,診斷準確度與敏感性分別為79%和64%。傳統分期組中,診斷準確度與敏感性分別為60%和32%。
  
  【確認另一個研究】
  這篇新研究的發現與另一篇試驗的結果相似。另一篇研究是由荷蘭阿姆斯特丹綜合癌症中心的Harm van Tinteren醫師領銜,研究的NSCLC病患數差不多(188人),不過其中70%的病患有局部疾病,新研究的則是34%。然而,該研究獲得相似的結果,顯示獨立運用PET進行分期,可使無效之胸廓切開術的絕對風險降低達20% (van Tinteren H 等人。Lancet. 2002;359:1388-1393)。
  
  不過,有另一個比較這兩個研究的試驗有不同的結果。在澳洲一個有184名病患的研究中,其中92%有局部疾病,隨機接受獨立運用PET進行分期以及接受傳統分期這兩組病患中,胸廓切開術的數目沒有差異(Viney RC等人。J Clin Oncol. 2004;22;2357-2362)。
  
  最新研究的作者指出,不過,這篇澳洲研究並未使用有確認性的侵犯性檢查—184名病患中只有10人接受胸膈鏡。在他們自己的研究中,94% 的病患接受胸膈鏡,Fischer博士等人認為,這是其研究的強度之一。這些接受胸膈鏡的病患11%有淋巴結陽性的結果。因此,這些病患在目前的手術中被視為無法手術的疾病,但是在澳洲的研究中則無法如此分類;Fischer博士等人認為,簡而言之,缺乏胸膈鏡削弱了澳洲的研究發現。
  
  目前研究的研究限制之一是,它未符合納入目標,也因為人數增加太慢而停止了。
  
  作者們寫道,該研究原本希望每組病患有215人(總共430人進行隨機分組),才可以有足夠的強度發現兩組之間無效的胸廓切開術數量有15%的差異。不過,該研究在只有納入189名病患之後停止。發表的研究是這些資料的首次分析。
  
  【存活沒有顯著差異】
  作者們發現,PET第一個被核准的適應症是用於NSCLC分期。併用PET-CT在2001年後迅速取代單獨使用PET。他們指出,併用時的診斷能力已經被證實優於單用PET或CT。作者們寫道,優點主要是根據腫瘤分期評估較佳。
  
  儘管作為標準照護,對於改善診斷準確度能否被視為改善病患處置仍有不確定之處。目前的研究發現認為處置有改善。不過,兩組之間的存活沒有顯著差異,PET-CT組平均存活31個月,傳統分期組平均存活49個月(P = .29)。
  
  丹麥癌症協會與丹麥健康科技評估中心資助本研究。共同作者之一接受阿斯特捷利康藥廠的演講費用。其他無財經宣告。
  

PET-CT Is Better for Preoperative Staging of Lung Cancer

By Nick Mulcahy
Medscape Medical News

July 1, 2009 — The frequency of futile thoracotomies is reduced by use of combined positron-emission tomography and computed tomography (PET-CT) compared with conventional staging in patients with non–small-cell lung cancer (NSCLC), according to a new study.

PET-CT also reduced the total number of thoracotomies and improved diagnostic accuracy compared with conventional staging.

However, the use of this more expensive technology in the staging of these patients did not significantly affect overall survival, write the authors of the study in the July 2 issue of the New England Journal of Medicine.

Nevertheless, the authors of the study emphasize the benefits of PET-CT, including the fact that improved diagnostic accuracy can help avoid "resections of benign nodules and early local and distant relapse after surgery with curative intent." The authors were led by Barbara Fischer, PhD, from the department of oncology at the Odense University Hospital, in Copenhagen, Denmark.

The primary end point of the study, futile thoracotomy, is "controversial" in so far as it does not have a completely agreed-upon definition in the field, suggest the authors. In the study, a thoracotomy was considered futile in the event of any of the following clinical findings or results: a benign lung lesion, pathologically proven mediastinal lymph node involvement (stage IIIA [N2]), stage IIIB or IV disease, inoperable T3 or T4 disease, or recurrent disease or death from any cause within 1 year of randomization.

If that definition is accepted and futile thoracotomy is indeed considered a valid end point, write the authors, "the significantly higher number of early deaths and relapses in the conventional-staging group than in the PET-CT group was not due to chance or more successful surgery in the PET-CT group but instead reflects a better selection of patients for surgery in the PET-CT group."

Specifically, after staging, 60 patients in the PET-CT group (out of a total of 98) and 73 in the conventional-staging group (out of a total of 91) were considered to have operable disease and underwent thoracotomy.

Of the 60 patients in the PET-CT group, the thoracotomy was futile in 21 (35%), and of the 73 patients in the conventional-staging group, the procedure was futile in 38 (52%) (P = .05).

For the PET-CT group, the diagnostic accuracy and sensitivity were 79% and 64%, respectively. For the conventional-staging group, the accuracy and sensitivity were 60% and 32%, respectively.

Confirms Another Study

The new study's findings are similar to the results of another trial. That study, led by Harm van Tinteren, MD, from the Comprehensive Cancer Center Amsterdam, in the Netherlands, involved a similar number of patients (188) with NSCLC, although 70% of these patients had localized disease vs 34% in the latest study. Nevertheless, that study yielded a similar result and showed that staging with stand-alone PET resulted in an absolute risk reduction of futile thoracotomy by 20% (van Tinteren H et al. Lancet. 2002;359:1388-1393).

But there is 1 other trial that is comparable to these 2 studies that had different results. In an Australian study of 184 patients, 92% of whom had localized disease, there was no difference in number of thoracotomies between the 2 randomized comparison groups: patients who underwent staging with stand-alone PET and those who underwent conventional staging (Viney RC et al. J Clin Oncol. 2004;22;2357-2362).

However, this Australian study did not use confirmatory invasive procedures — only 10 of the 184 patients underwent mediastinoscopy, the authors of the latest study point out. In their own study, 94% of the patients underwent mediastinoscopy, which was "one of the strengths of the study," Dr. Fischer and colleagues comment. Eleven percent of the patients had positive lymph nodes on mediastinoscopy. Thus, these patients were considered to have inoperable disease in the current study but would have not been so classified in the Australian study; in short, the lack of mediastinoscopy weakens the Australian findings, Dr. Fischer and colleagues suggest.

One of the limitations of the current study is that it did not meet enrollment goals and was closed due to slow accrual.

The study was designed so that 215 patients would be randomized to each group (for a total of 430 patients), thus allowing enough power to detect a difference of 15% in the number of futile thoracotomies between the 2 groups, write the authors. However, the study was closed after enrolling only 189 patients. The published study is the first analysis of the data.

No Significant Difference in Survival

The staging of NSCLC was 1 of the first approved indications for PET, the authors observe. The combined PET-CT "has rapidly replaced stand-alone PET" since 2001, they add. The diagnostic capability has been proven to be superior to either PET or CT alone, they add. The advantage is mainly based on the superior assessment of tumor stage, the authors write.

Despite being the standard of care, there has been uncertainty about whether or not improved diagnostic accuracy translates into improved management of patients. The findings of the current study suggest that management is improved. However, there were no significant differences in survival between the 2 groups, with a median survival of 31 months in the PET-CT group and 49 in the conventional staging group (P = .29).

The study was supported by grants from the Danish Cancer Society and the Danish Center for Health Technology Assessment. One of the coauthors has received lecture fees from AstraZeneca. No other financial relationships were disclosed.

New Engl J Med. 2009;361:32-39.

    
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