Zoledronic Acid可對抗乳癌治療後的骨質流失現象

  Dec. 9, 2004 (聖安東尼奧) - 在以輔助性荷爾蒙療法對停經前乳癌患者作治療時,骨質流失現象是一項很明顯的副作用,但是根據一項隨機性的第3期臨床試驗結果顯示,骨質流失是可以補償的,也就是每6個月注射一次bisphosphonate zoledronic acid即可。
  這項臨床試驗包含4個試驗組,主導機構為Austrian Breast and Colorectal Cancer Study Group(ABCSG-12),一共有1315位的停經前乳癌患者參與;兩組為goserelin及tamoxifen加上zoledronic acid,或無zoledronic acid,另兩組則為goserelin及aromatase抑制劑anastrozole加上zoledronic acid,或無zoledronic acid。
  在聖安東尼奧乳癌論壇第27屆年會中,奧地利維也納大學的Michael Gnant醫師提出他的研究結果表示,接受anastrozole治療的患者,其骨質流失的狀況會比tamoxifen嚴重;所有的患者都接受goserelin,而已知這類藥物對於骨質密度(BMD)有負面的影響。
  當被問到治療法是否會引發骨質流失時,Gnant醫師回答是肯定的,zoledronic acid是否可以對抗骨質流失,Gnant醫師也回答也是肯定的。
  Gnant醫師的試驗參與者有401位患者作過BMD的測量,其中tamoxifen組的103位及anastrozole組的94位沒有使用zoledronic acid;使用zoledronic acid的患者,在tamoxifen組有100位,anastrozole組有104位。
  經過36個月後,兩組無zoledronic acid的患者,其腰椎BMD值下降了14.4%;每6個月接受一次15分鐘zoledronic acid注射的患者,其BMD值和試驗初期相似。
  在作完4組的比較後,Gnant醫師進一步指出,在tamoxifen組中無zoledronic acid的患者,其腰椎BMD值下降了11.6%,anastrozole組則下降了17.4%;接受zoledronic acid治療的患者中,anastrozole組的BMD值稍微下降,tamoxifen組反而微幅上升。
  沒有接受zoledronic acid的anastrozole治療組,比較容易有骨質減少及骨質舒鬆的現象;Gnant醫師表示,目前為止,我們只有一個骨折的案例。
  英國Royal Marsden Institute of Cancer Research的Trevor Powles醫師正在以bisphosphonate clodronate作為骨轉移的預防研究;他表示,對於BMD的正面及負面影響是可以預期的;但是zoledronic acid是否真的會降低骨折的機率,時間會告訴我們;我們預期任何的bisphosphonate都會降低骨質流失的現象,至於是否會減少骨折,就不知道了。

Zoledronic Acid May Counteract

By Jane Salodof MacNeil
Medscape Medical News

Dec. 9, 2004 (San Antonio) — Bone loss is a significant adverse effect of adjuvant hormonal treatment in premenopausal breast cancer patients, but data from a randomized phase 3 trial have shown that it can be offset by an infusion of the bisphosphonate zoledronic acid administered once every six months.

The four-group trial, conducted by the Austrian Breast and Colorectal Cancer Study Group (ABCSG-12), randomized 1,315 premenopausal women to goserelin plus tamoxifen with or without zoledronic acid vs goserelin plus the aromatase inhibitor anastrozole with or without zoledronic acid.

Michael Gnant, MD, from the University of Vienna in Austria, reported that bone loss was more severe in patients receiving anastrozole compared with those receiving tamoxifen. All of the women were also receiving goserelin, which he noted likely worsened the known adverse effects of anastrozole on bone mineral density (BMD). Dr. Gnant presented the results here yesterday at the 27th annual San Antonio Breast Cancer Symposium.

"Is there significant cancer treatment–induced bone loss? Yes. Can this be counteracted by zoledronic acid? Again, the answer is yes," Dr. Gnant said.

Dr. Gnant reported on 401 patients for whom BMD measurements were available. 103 patients receiving tamoxifen therapy and 94 receiving anastrozole did not receive the bisphosphonate, while zoledronic acid was given to 100 patients receiving tamoxifen and 104 receiving anastrozole.

After 36 months, BMD measurements of the lumbar spine decreased by 14.4% in the two groups not given zoledronic acid. Levels were similar to baseline, however, for patients who received 4 mg of zoledronic acid in a 15-minute intravenous infusion every six months.

In a four-group comparison, Dr. Gnant further showed that without zoledronic acid treatment, lumbar spine BMD declined by 11.6% in patients receiving tamoxifen and by 17.4% for those receiving anastrozole. When zoledronic acid was added, lumbar spine BMD decreased slightly in patients receiving anastrozole and increased slightly in the cohort receiving tamoxifen.

Patients receiving anastrozole without zoledronic acid were also more likely to have osteopenia or osteoporosis. "So far, we have not observed a single fracture in the trial," Dr. Gnant said.

Neither patient age nor BMD at baseline affected the amount of bone loss, according to the analysis. Dr. Gnant said renal safety was not a problem and no cases of osteonecrosis had been observed.

Trevor Powles, MD, from the Royal Marsden Institute of Cancer Research in Sheffield, U.K., who is investigating the use of the bisphosphonate clodronate to prevent bone metastases, said the negative and positive effects on BMD were to be expected and that time will tell whether zoledronic acid would reduce fracture risk in the Austrian trial. "We would anticipate that any of the bisphosphonates will reduce bone loss," he said. "Whether that will prevent fractures, we don't know."

Use of aromatase inhibitors will grow despite their known negative effects on BMD, Dr. Powles continued. Physicians and patients should weigh such factors as bone status before hormonal treatment, choice of aromatase inhibitors, and the risk of recurring breast cancer. "The risk of cancer of the breast will substantially outweigh the risk of osteoporosis," he predicted.

27th Annual San Antonio Breast Cancer Symposium: Abstract 6. Presented Dec. 8, 2004.

Reviewed by Gary D. Vogin, MD

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