本帖最後由 yanjw2000 於 2009-7-28 21:49 編輯
作者：Roxanne Nelson
出處：WebMD醫學新聞
July 10, 2009 — 正子斷層造影(PET)合併電腦斷層掃描(CT)是肺癌分期的合理選項，特別是那些適合治癒性治療的病患。
6月6日內科醫學檔案期刊線上版中，研究者發現，以PET-CT和顱內影像進行術前分期，可以比傳統分期方式確認更多縱膈腔疾病和胸腔外疾病患者。不過，雖然此方法有助於降低分期不適當的手術，但是也有5% PET-CT使用者的分期被錯誤提升。
作者指出，手術仍然是早期非小細胞肺癌(NSCLC)的適當治療方式，但是在預期可以治癒的手術之後的復發率依舊高。被視為可以手術切除的病患，將接受次數不等的影像檢查，以確認有無轉移和避免不必要的手術。
PET被視為一種可以偵測出轉移的影像方式，當併用CT時，兩者的功能性與解剖方面資訊可以同步。如同Medscape Oncology 以前所報導的，研究已經發現，使用PET-CT可以降低無效胸廓切開術的頻率。
【局勢轉向PET-CT】
不過，根據編輯評論，對於許多醫師來說，局勢已經趨向PET-CT。
賓州大學賓州退伍軍人醫學中心醫學臨床副教授Mitchell L. Margolis醫師寫道，自從1980年代末期將PET導入臨床腫瘤方面之後，已經引起相當大的興趣。此技術在診斷、分期、導引切片、評估治療反應、確認復發疾病等方面有廣泛的運用潛力。對於肺癌，使用PET特別有用，因為它提供源發病灶、縱膈腔、遠端轉移等相關資訊。
根據Margolis醫師表示，肺癌分期是多數治療決策的基礎，而分期系統越趨複雜。因此，費用合理且精準分期肺癌的單一非侵犯性檢查方式，將是避免無效的手術或治療不足的重要進展。
Margolis醫師指出，PET-CT不只被許多醫師接受，還有其他許多詳盡的研究確認其臨床角色，包括現在這項試驗。
不過，有關使用PET-CT仍有許多問題有待解答。舉例來說，Margolis醫師問道，「整合PET-CT這麼棒的話，那單用CT或PET在肺癌分期上是否會被淘汰？」、「這些優點值得增加花費嗎？」
他問道，併用影像檢查或者取代影像檢查之外，即使縱膈腔結節小且PET為陰性，我們仍應固定進行內視鏡超音波切片，以進行縱膈腔組織分期嗎？需要哪種等級的證據以在這多種檢查方式中確認偏好哪一種，特別是現有諸多方法的多種併用方式？
Margolis醫師寫道，仍有許多議題，當可能的檢查方式持續增加、且個別檢查的重要技術純熟時，難以做出適當之術前評估的正式建議。
不過，他指出，這目前還在發展中，對醫師來說，醫囑使用PET-CT進行肺癌分期是合理的，特別是那些適合治癒性治療的病患。Margolis醫師表示，建議使用PET-CT並非代表其他術前評估方式無效或不被接受；選擇的檢查方式端賴個人的經驗與當地有無該項檢查方式。我們需要更多有關PET-CT和其他分期方式的比較研究，以瞭解臨床結果和費用分析等，使肺癌分期持續進步和改善。
在目前這項愛荷華大學胸腔外科Donna E. Maziak醫師領導的研究中，比較PET-CT與傳統分期方式用於考慮進行手術的NSCLC病患，以確認哪些病患的疾病分期錯誤。
Maziak醫師等人將337名確認為臨床I、II或IIIA期的NSCLC病患隨機分派接受PET-CT加顱內影像或傳統分期方式(腹部CT、包括肝臟與腎上腺與骨骼掃描)加顱內影像。這些病患中，8名病患(3人接受PET-CT以及5人接受傳統方式)後來未進行原本計畫的手術。
最後的分析包括了329名病患(167人屬於PET-CT組，162人屬於傳統分期組)，PET-CT組中有83名病患、傳統分期組中有85名病患接受縱膈腔鏡。PET-CT組中有138名病患、傳統分期組中有131名病患進行胸廓切開術。
【正確分期與錯誤提升分期的比率較高】
研究者指出，PET-CT組中有23名病患、傳統分期組中有11名病患的分期被正確提升(13.8% vs 6.8%；差異7.0百分比[95% CI，0.3 – 13.7百分比])。這些病患可以避免不必要的手術。PET-CT組中有8名病患、傳統分期組中有1名病患的分期被錯誤提升(4.8% vs 0.6%；差異4.2百分比[95% CI，0.5 – 8.6百分比])，PET-CT組中有25名病患、傳統分期組中有48名病患的分期被錯誤降級(14.9% vs 29.6%；差異14.7百分比[95% CI，5.7 – 23.4百分比])。
PET-CT組與傳統分期組的平均追蹤期間分別為21.8個月和22.5個月，整體來說，在3年的追蹤期間，有109名(52名為PET-CT組，57名為傳統組)病患死亡。大多數病患(83.5%)是死於肺癌。
他們指出，試驗有一些限制，包括樣本數相對較少。此外，因為可以進行PET-CT的機構也較少，比較容易達到嚴格的品管指引。因此，這些結果可能無法完全一般化到更大範圍，因為影像機器有多種型號。
但是，相較於傳統方期方式，PET-CT方式使正確分期的腫瘤病患數達兩倍，而這是對所有腫瘤分期觀察得來，他們寫道，對於末期腫瘤分期，可以發現的病患數更多。傳統分期方法比較常發現骨轉移，PET-CT可以偵測更大範圍的轉移。
作者結論表示，以PET-CT進行術前分期可以比傳統分期方式確認更多縱膈腔疾病和胸腔外疾病的患者。不過，PET-CT掃描的偽陽性縱膈結節，可能會不慎讓病患無法進行可能治癒的手術。
安大略健康與長照部、加拿大健康研究中心、安大略癌症照護等支持本研究。研究作者與編輯皆無相關利益衝突之宣告。
Ann Intern Med.。線上發表於2009年7月6日。
Has the Pendulum Swung to PET-CT in Lung-Cancer Staging?
By Roxanne Nelson
Medscape Medical News
July 10, 2009 — Positron-emission tomography (PET) combined with computed tomography (CT) is a reasonable option for staging lung cancer, especially among patients who appear to be candidates for curative therapy.
Reporting online July 6 in the Annals of Internal Medicine, researchers found that preoperative staging with PET-CT and cranial imaging identified more patients with mediastinal and extrathoracic disease than conventional staging. But while this helped reduce stage-inappropriate surgery, the strategy also incorrectly upstaged disease in almost 5% percent of PET-CT recipients.
Surgery remains the optimal treatment for early-stage non–small-cell lung carcinoma (NSCLC), but the recurrence rate after intended curative resection is high, note the authors. Patients being considered for surgical resection will undergo any number of imaging tests to detect metastases and avoid unnecessary surgery.
PET has emerged as an imaging modality to detect metastases, and when combined with CT, both functional and anatomical information are provided simultaneously. As previously reported by Medscape Oncology , studies have already shown that the frequency of futile thoracotomies can be reduced by the use of PET-CT.
Pendulum Swinging to PET-CT
However, for many clinicians, the proverbial pendulum has already swung to PET-CT, according to an accompanying editorial.
PET has engendered an enormous amount of interest since its introduction into clinical oncology in the late 1980s, writes Mitchell L. Margolis, MD, a clinical associate professor of medicine at the Philadelphia Veterans Affairs Medical Center and University of Pennsylvania. The technique has a wide range of potential applications in diagnosis, staging, guiding biopsies, assessing response to therapy, and identification of recurrent disease. In lung cancer, the use of PET has been particularly promising, since it provides information about the primary lesion, mediastinum, and distant metastases.
Lung-cancer staging is the foundation for most treatment decisions, and the staging system grows more complex with each iteration, according to Dr. Margolis. Therefore, a single noninvasive test that could accurately stage lung cancer at a reasonable cost would be major step forward in avoiding futile surgery and inappropriate undertreatment.
Not only has PET-CT been embraced by many clinicians, but the modality has been "increasingly validated by many detailed studies that have served to clarify its clinical role," notes Dr. Margolis, including the current trial.
However, many questions regarding the use of PET-CT remain unanswered. For example, asks Dr. Margolis, "Is integrated PET-CT so superior that CT or PET alone is now obsolete for staging lung cancer?" Or are the "putative advantages worth the increased cost?"
"Should we routinely do endoscopic ultrasonic biopsy — in addition to or instead of imaging — even if mediastinal nodes are small and PET-negative, in an attempt to stage the mediastinum histologically?" he asks. And "what level of evidence is necessary to establish a clear preference for 1 of several tests, especially given the many available tests that we could compare in various combinations?
"Many issues remain, and it is particularly difficult to formulate recommendations for optimal preoperative assessment when the number of possible tests is increasing, along with important technical refinements in individual tests," writes Dr. Margolis.
However, he notes that at "this point in an evolving saga," it is reasonable for clinicians to order PET-CT to stage lung cancer, particularly among patients who appear to be candidates for curative surgical resection. "A recommendation to use PET-CT is not to say that other means of preoperative assessment are invalid or unacceptable; preferences among imperfect tests always depend on local expertise and test availability," says Dr. Margolis. "We will need additional comparisons between PET-CT and other staging tests — preferably studies that measure clinical outcomes and include cost analyses — as lung-cancer staging continues to transform and improve."
In the current study, a team led by Donna E. Maziak, MDCM, from the division of thoracic surgery at the University of Ottawa, in Ontario, compared PET-CT with conventional staging in patients with NSCLC being considered for surgery to determine the proportion of patients in whom disease was correctly upstaged.
Dr. Maziak and colleagues randomized 337 patients with confirmed clinical stage I, II, or IIIA NSCLC to undergo PET-CT plus cranial imaging or conventional staging (abdominal CT, including the liver and adrenals, and bone scan) plus cranial imaging. Of this cohort, 8 patients (3 who had PET-CT and 5 who had conventional staging) subsequently did not proceed with planned surgery.
The final analysis set included 329 patients (167 in the PET-CT group and 162 in the conventional-staging group), with 83 patients in the PET-CT group and 85 in the conventional-staging group undergoing mediastinoscopy. Thoracotomy was performed on 138 in the PET-CT group and 131 in the conventional-staging group.
Higher Rates of Correct and Incorrect Upstaging
The researchers noted that the disease was correctly upstaged in 23 PET-CT recipients compared with 11 patients in the conventional-staging group (13.8% vs 6.8%; difference, 7.0 percentage points [95% CI, 0.3 – 13.7 percentage points]. These patients were able to avoid unnecessary surgery. Disease was incorrectly upstaged in 8 PET-CT recipients and 1 conventional-staging recipient (4.8% vs 0.6%; difference, 4.2 percentage points [95% CI, 0.5 – 8.6 percentage points]), and it was incorrectly understaged in 25 PET-CT recipients and 48 patients in the conventional group (14.9% vs 29.6%; difference, 14.7 percentage points [95% CI, 5.7 – 23.4 percentage points]).
The median follow-up was 21.8 months in the PET-CT group and 22.5 months in the conventional-staging group, and overall, 109 patients (52 PET-CT and 57 conventional) died during the 3-year study period. The majority of patients (83.5%) died of lung cancer.
They note that the trial has some limitations, including a relatively small sample size. Also, because there were relatively few locations where the PET-CT scan could be conducted, adherence to strict quality-control guidelines was easier to achieve. Therefore, these results may not be fully generalizable in larger settings that incorporate many different types of imaging machines.
But as compared with conventional staging, staging with PET-CT doubled the proportion of patients whose tumor was correctly upstaged, and while this was observed at all tumor stages, it was greater in patients who presented with more advanced tumor stage, they write. While conventional-staging methods most often detected bone metastases, PET-CT was able to detect a wider range of metastases.
"Preoperative staging with PET-CT identified more patients with mediastinal and extrathoracic disease than conventional staging did," the authors conclude. "However, falsely positive mediastinal nodes on PET-CT imaging can inadvertently exclude patients from potential curative surgery."
The study was supported by the Ontario Ministry of Health and Long-Term Care, the Canadian Institutes of Health Research, and support from Cancer Care Ontario. No potential financial conflicts of interest were disclosed by the study authors or editorialist.
Ann Intern Med. Published online July 6, 2009. |
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