對乳癌新確診患者而言 MRI可能扮演關鍵角色


  May 24, 2007 — 對剛被診斷出罹患乳癌的患者而言,磁振造影(MRI)可能扮演決定採用何種手術治療的關鍵角色。於《外科檔案》期刊發表的研究中,發現接受MRI輔助診斷的乳癌患者,有9.7%的患者在手術治療上因而獲得有益的改變。
  
  Kevin P. Bethke醫師表示,我們的研究將MRI視為選用何種手術治療方式的理想工具,以MRI發現的結果觀之,到底術前評估有沒有因此改變;但更重要的是,我們想要去看究竟MRI所帶來的改變是好或是壞;Bethke醫師為伊利諾州芝加哥市西北大學Feinberg醫學院外科腫瘤學部臨床外科的臨床助教。
  
  乳房MRI已被當作篩檢工具來研究,而根據研究報告執筆者的說法,該研究已顯示在乳房惡性腫瘤的偵測上,乳房MRI具有93%至100%的敏感度;剛被診斷出罹患乳癌的女性中,MRI已經能夠對27%至37%的患者,去識別出其他在之前未偵測出的病灶;因此,對於腫瘤併發、初期腫瘤之多灶性(multifocality)和腫瘤多中心性(multicentricity),以及早期病灶可能最終惡化成惡性腫瘤,該技術具有診測的潛力。
  
  於為期1年的研究期間,155名剛被診斷出罹患乳癌的女性,所接受的診測法包括乳房X光攝影、超音波和粗針切片檢查法,再加上術前兩側乳房MRI篩檢;Bethke醫師向Medscape表示,傳達出我們的研究具有極高的一致性是重要的,我們僅聘用1間醫學中心的1名外科醫師對所有的患者進行評估,並於限定時間內完成,因此研究理念是貫徹始終的,而且同期間沒有其他的研究同步進行,研究中所使用的儀器裝備始終保持一致,而且我們的放射科醫師克盡職守。
  
  拿來和其他的研究做比較,他們會遇到變數所帶來的影響,像是使用不同的儀器裝備、受測患者接受不同的檢測、同時研究規範會依不同的醫學中心而有所不同;Bethke醫師表示,我們研究的例行程序相當嚴謹,且與之前部分研究相比,完全在掌控中。
  
  【MRI的結果影響手術治療的選擇】
  在73名女性中,乳房MRI另外多識別出124件可疑的病灶,而結果則是,其中36名女性(23.2%)的手術治療作了改變;此組受測對象中有65名女性需要再作額外的造影檢驗,而另外18名女性中有2名直接接受更大範圍的乳房切除,以及6名女性接受6個月的追蹤診治。
  
  Bethke醫師解釋道,在做過一次MRI後,大部份的患者回頭接受額外的造影檢驗,MRI的敏感度很高,但專一度不強,因此它會造成為數不少的偽陽性,如此即需要額外的造影檢驗,以及額外的影像導引粗針切片檢查。
  
  額外再作造影檢驗的65名女性當中,有24名原先在MRI中顯現出有可疑的病灶,在後續的超音波檢查和乳房X 光攝影檢查則確定為良性;而另外41名女性接受影像導引粗針切片檢查,其中有9名患者顯示出惡性腫瘤的檢驗結果,4名有非典型腺管增生(atypical ductal hyperplasia)或非典型小葉增生(atypical lobular hyperplasia),而剩下的28名則為良性病灶;由MRI所偵測出的病灶,再作切片檢查得到偽陽性的機率為78.0%。
  
  乳房MRI因為專一度不足,可能會導致患者極度焦慮是否還需要額外的檢查,以及接受切片和額外影像的額外花費;Bethke醫師舉例,有2位女性接受了不必要的反側乳房切除手術,只因為她們不想作切片檢查,而她們之所以會作此決定,是因為焦慮的關係。
  
  依據MRI篩檢的結果,有10名患者原先安排作乳房腫瘤切除手術,後來改接受乳房切除手術,有8個人因此而受益;21名患者接受更大範圍的乳房切除,其中有10人受益;另有5名患者接受反側乳房切除手術,其中有2人受益;較大的腫瘤則被視為是因此改做手術治療而受益的獨立指標。
  
  參酌術前MRI的結果而改作手術治療的36名患者中,在放射線病理的再次確認上,該改變對41.7%人是有益的;整體而言,術前先作乳房MRI,對9.7%的患者能帶來手術治療的改變是有益的,意指有十分之一的女性必須接受乳房MRI,才能在手術治療的改變上帶來益處。
  
  Bethke醫師指出,乳房MRI中有一個學習曲線,在第一個半年期和第二個半年期之間,我們的正向改變不只加倍,我們開始在研究起始時大量的做乳房MRI,而隨著時間的推演,改善的狀況就愈來愈好。
  
  Bethke醫師表示,最終的研究將顯示出MRI改善了整體的存活率,但我們還沒達到目標;我懷疑我們將永遠無法辦到,因為我認為歸功於MRI的僅是整體存活率中的小小進展,而要去檢驗和證明將會相當困難。
  
  此外,他相信隨著時間的進展,運用MRI將會協助降低局部的復發率。
  
  Bethke醫師解釋道,之所以會進行這項研究,是因為我們對於乳房MRI使用方針的短缺,實在是感到氣餒;但在他們的研究完成之後,統計上的分析也真的沒有分辨出任何特定的群組能特別從MRI得到益處。
  
  Bethke醫師的研究團隊無法歸納出特定的方針作為其研究的結論,但Bethke醫師解釋道,對於剛被診斷出罹患乳癌的女性要做MRI,他自己目前行醫的參照指標是以40歲以下、乳房組織密實、多灶性疾病、侵入性小葉疾病及潛在性乳癌的女性為準。
  
  Bethke醫師認為,專一度將會持續的改善,而專一度愈佳,它就會愈有效果;專一度愈佳,可靠性就愈高,患者焦慮感就會降低,而造成較大正面影響的機會就愈高。

Possible Role for MRI in Patie

By
Medscape Medical News

May 24, 2007 — Magnetic resonance imaging (MRI) of the breast may play a role in determining surgical treatment among women who are newly diagnosed with breast cancer. The study, which appears in the May issue of the Archives of Surgery, found that the use of MRI resulted in a beneficial change in the surgical management of 9.7% of patients.

"Our study looked at MRI as a tool to better determine surgical management," said study author Kevin P. Bethke, MD, a clinical assistant professor of clinical surgery, division of surgical oncology, at Northwestern University's Feinberg School of Medicine, in Chicago, Illinois. "We were looking to see whether there was a change in preoperative evaluation, based on the result of the MRI findings. But more important, we wanted to see if the change was beneficial or nonbeneficial."

Breast MRI has been investigated as a screening tool, and studies have shown it to have a sensitivity of 93% to 100% in detecting breast malignancies, according to the authors. In women with newly diagnosed disease, MRI has been able to identify additional, previously undetected lesions in 27% to 37% of patients. Therefore, the technology has the potential of identifying synchronous tumors, multifocality and multicentricity of the primary neoplasm, and early lesions that might eventually develop into a malignancy.

During a period of 1 year, 155 women with breast cancer newly diagnosed by mammogram, ultrasound, and needle biopsy underwent preoperative bilateral breast screening with MRI. "It is important to note that our study had a lot of consistency," Dr. Bethke told Medscape. "We had only 1 surgeon in a single institution who evaluated all of the patients. It was done over a limited time period, so there wasn't any evolution in thinking or other studies done during that time. The equipment remained essentially the same, and we had dedicated radiologists."

This is comparison with other studies, where other variables come into play, such as different equipment, patients receiving different testing, and protocols that vary according to individual institutions. "We had a pretty regimented routine, and it was well controlled compared with some of the previous studies," he said.

Surgical Management Altered as a Result of MRI

Breast MRI identified 124 additional suspicious lesions in 73 of the women, and as a result, surgical management was altered in 36 (23.2%) of them. Of this group, 65 women required further imaging, while 2 of the remaining patients proceeded straight to wider excision and 6 underwent a follow-up at 6 months.

"A large percentage of patients are brought back for additional imaging after an MRI," explained Dr. Bethke. "The MRI is very sensitive but not very specific, so it causes a large number of false positives. That requires additional imaging and additional image-guided core needle biopsies."

Among the 65 patients who underwent further imaging, the suspicious area seen on MRI appeared to be benign with follow-up ultrasonography and mammography in 24 of them. The remaining 41 women had an image-guided biopsy. Results showed a malignancy in 9 of the patients, 4 had atypical ductal hyperplasia or atypical lobular hyperplasia, and the remaining 28 had benign lesions. The false-positive rate for biopsy of an MRI-detected lesion was 78.0%.

The lack of specificity of breast MRI can cause significant patient anxiety about needing an additional workup, as well as the additional cost of biopsy and further imaging. "Two women had an unnecessary contralateral mastectomy because they did not want to undergo a biopsy," said Dr. Bethke, "And their decision was related to anxiety."

As a result of MRI screening, a planned lumpectomy was converted to mastectomy in 10 patients, with 8 beneficial; a wider excision was performed in 21 patients, 10 of which were beneficial; and 5 patients underwent contralateral surgery, 2 of which were beneficial. A larger tumor size was found to be an independent predictor of a beneficial alteration in surgical management.

In the 36 patients who had a change in surgical management based on preoperative MRI results, the change was found beneficial in 41.7% on radiographic-pathological confirmation. Overall, the use of preoperative breast MRI resulted in a beneficial change in surgical management in 9.7% of patients, meaning that 10 women must undergo a breast MRI for 1 to have a beneficial change in management.

Dr. Bethke pointed out that there is a learning curve in breast MRI. "Our beneficial change more than doubled between the first 6-month period and the second one. We started doing high-volume breast MRI with the beginning of this study, and there was a significant improvement as time went on.

"The ultimate study would show that the MRI improves overall survival, but we don't have that," he said. "I suspect that we may never have that, because I think that only an overall small improvement in survival that can be attributed to MRI, and that will be very difficult to test and prove."

Instead, he believes that over time, the use of MRI will help decrease local recurrence rates.

"The study was done because we were frustrated by a lack of guidelines for using breast MRI," he explained, although after their study was completed, statistical analysis really did not break out any specific group for whom MRI would be particularly beneficial.

The researchers were unable to come up with specific guidelines as a result of their study, but Dr. Bethke explained that his own current indications for performing an MRI in newly diagnosed patients with breast cancer would be in women under the age of 40 years, patients with dense breast tissue, patients with multifocal disease, patients with invasive lobular disease, and those with occult breast cancer.

"I think the specificity will continue to improve, and the better the specificity, the more useful it will be," Dr. Bethke said. "The better the specificity, the better the reliability, the less patient anxiety, and the greatest chance to make a bigger impact."

Arch Surg. 2007;142:441-447.

    
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