乳房造影技術有助於確認哪些年輕婦女需要篩檢


  May 10, 2005 (舊金山) - 美國婦產科醫學會的第53屆年會上一項發表指出,40歲以下的年輕婦女,可以藉由一項新的乳房造影技術,確認是否需要更進一步的乳癌診斷。
  
  主研究員Alexander Stojadinovic醫師指出,電阻抗系統(EIS)的研究人員試圖利用該系統,將高乳癌風險的年輕的婦女篩檢出來,因為較之更年期後的婦女,年輕婦女的乳房組織具有較高的密度;傳統X光乳房攝影的準確度較低,而使用新系統所獲致的正面效果,有助於醫師們對於這個年齡層的婦女作診斷,並可藉此篩檢出可以受益於進一步乳房造影的婦女。
  
  Stojadinovic進一步表示,EIS的電子訊號在乳房細胞內所產生的改變,即是該系統所運用的生物原理;在早期的癌細胞形成過程中,這個電子訊號就會有所改變。
  
  EIS乃根據乳房組織所引發的電子訊號產生造影,患者在造影進行時,必須手握一圓筒型器材作為地線,同時,另一儀器則以一定的順序,在乳房的9個區塊中進行掃描,包含乳頭部位;掃描的儀器會和該圓筒型器材產生電流,所獲得的數據會自動輸入於一電腦中,在電腦螢幕上產生造影。
  
  該系統的二進位演算系統會將所獲的數據歸類為「正常」或「可疑」,獲得「可疑」結果的婦女,將必須接受進一步的診斷,例如診斷式的乳房造影;較之篩檢式的乳房造影、超音波或核磁共振(MRI),診斷式的乳房造影具有更高的敏感度;Stojadinovic強調,因為EIS尚在研究階段,所以他或其他的研究人員皆不會偏向任何一種後續的追蹤造影法。
  
  雖然年經的婦女較之更年期後的婦女,有著較低的乳癌風險,但是具有遺傳風險因子的婦女,在年輕時會有較高的乳癌發生率;而這類的年輕婦女,常常在癌症到達末期時,才被診斷出來;因為通常是在乳房產生可觸知的多餘息肉時,乳癌才被偵測出來。
  
  本項研究由EIS技術的研發公司Mirabel Medical Systems, Inc所資助;研究人員招募了1163位40歲以下的婦女參與試驗,所有的婦女皆經過EIS掃描;該公司正在進行一些相關研究,並計畫向美國食品藥物管理局提出申請,希望獲得該項適應症的使用核可。
  
  為了評估該項系統的特定性,研究人員針對601位非乳癌高風險的婦女進行試驗;結果顯示,578位的婦女有著正常的結果,亦即,特定性為96.2%。
  
  對於562位EIS掃描結果為高風險的婦女,研究人員將之歸納為6個類別:(1) 253位因無可疑的腫瘤細胞,所以不需要進一步造影;(2) 200位雖然未顯示任何的異常,仍被EIS系統確認需要更進一步的造影檢查;(3) 16位雖未接受切片檢查,但經造影後發現,有著1個以上的非癌細胞腫瘤;(4) 84位為低風險的良性瘤,這個結果已經切片檢查證實;(5) 6位為高危險的良性瘤;(6) 3位則確定罹患癌細胞腫瘤。
  
  因此,對於確定為高危險的年輕患者,EIS系統的陽性結果敏感度關係著上述類別的風險度,如第(1)類的敏感度為2.8%,第(2)類為2.0%,第(3)類為6.0%,第(4)類為5.0%,第(5)類為33.3%,第(6)類為66.7%;Stojadinovic表示,整體的敏感度為33%;根據該項研究,相較於一般的婦女,EIS呈現陽性結果者,乳癌的風險率高出7倍。
  
  紐約大學婦產科醫學系的教授Steven R. Goldstein醫師表示,對於年輕患者的特定次族群,有必要作確認性的診斷,將需要乳癌造影篩檢的患者指認出來;這個方法是合理的,因為自從1920年起,我們就知道乳房腫瘤所產生的導電度會不同於正常組織。

Breast Imaging Technology May<

By Paula Moyer, MA
Medscape Medical News

May 10, 2005 (San Francisco) — A novel breast imaging technology may help identify which women younger than 40 years need further diagnostic studies for breast cancer, according to findings presented here at the 53rd annual meeting of the American College of Obstetricians and Gynecologists.

The investigators of the electrical impedance system (EIS) wanted to know if it could be used to screen younger women who have an increased risk of breast cancer. Because their breast tissue is denser than that of postmenopausal women, conventional screening mammography is less accurate, according to principal investigator Alexander Stojadinovic, MD. A positive result with the new system may help physicians identify women in this age group who would benefit from additional breast imaging.

"The biological basis for EIS stems from the electrical signal changes we see in breast cells," said Dr. Stojadinovic, vice-chairman of surgery at the Walter Reed Army Medical Center in Washington, D.C. The signal change occurs early in the carcinogenesis process, he added.

EIS produces a breast image based on the electrical signals from breast tissue. The patient holds a cylinder that serves as a ground, and another instrument is held sequentially over the nine segments of the breast, including the nipple, which creates an electrical circuit with the cylinder. The data are fed into a computer and create an image on the computer screen.

The system's binary algorithm categorizes findings as either "normal" or "suspicious." The intent is that women with suspicious findings will undergo additional diagnostic work, such as a diagnostic mammography, which is more sensitive than a screening mammography, ultrasound, or magnetic resonance imaging (MRI). Dr. Stojadinovic stressed that because EIS is still investigative, neither he nor other investigators favor any particular imaging modality for follow-up imaging.

Although they are at less risk generally for breast cancer than postmenopausal women, women who have hereditary risks are more at risk of early breast cancer, which is often detected at a more advanced stage. This may be because the cancer is typically diagnosed after the woman has detected a palpable mass.

In a study funded by Mirabel Medical Systems, Inc., which developed the technology, the investigators recruited 1,163 women younger than 40 years. All of the women underwent scanning with EIS. The company is conducting ongoing research and planning to apply for U.S. Food and Drug Administration approval for this indication.

The investigators wanted to determine the system's specificity by analyzing the results in 601 of the women who had been determined to have no elevated risk of breast cancer. In those women, 578 had normal findings, for a specificity of 96.2%.

In the 562 women who had an elevated risk, the team classified them into six categories: (1) 253 who had no suspicious lesion, and therefore had no follow-up imaging; (2) 200 whose EIS indicated that further imaging was required but who had no abnormalities; (3) 16 who had one or more noncancerous lesions that were found on imaging but who did not undergo biopsy; (4) 84 who had a low-risk benign lesion confirmed by biopsy; (5) six who had a high-risk benign lesion; and (6) three who had a confirmed carcinoma.

Therefore, in younger patients identified as high risk, the investigators concluded that the sensitivity of a positive EIS was linked to the categories' increasing risk as follows: 2.8% in group 1; 2.0% in group 2; 6.0% in group 3; 5.0% in group 4, 33.3% in group 5, and 66.7% in group 6 (P < .001). The overall sensitivity was 33%, Dr. Stojadinovic said. A woman with a positive EIS result is seven times more likely to have breast cancer than a woman in the general population, the study showed.

"There's a need to identify a subgroup of young patients who need imaging studies to screen for breast cancer," said Steven R. Goldstein, MD. "The approach makes sense, because we've known since the 1920s that breast tumors have different electroconductance than normal tissue." Dr. Goldstein, who was not involved in the study, is a professor of obstetrics and gynecology at New York University in New York City.

Obstet Gynecol. 2005;105(4 suppl):4S. Presented May 9, 2005.

Reviewed by Gary D. Vogin, MD

    
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