癌症存活者的乳癌風險超出預期


  【24drs.com】童年時期患有癌症、曾使用放射線治療胸腔而存活者,發生乳癌的風險高於原本的預期。新資料認為應對這些人進行更廣泛的篩檢。
  
  目前,兒童腫瘤小組建議,接受過胸部放射線20 Gy以上的婦女,應每年進行乳癌檢查,使用乳房攝影或者胸部磁振造影,從25歲或者是接受放射線治療後8年開始。
  
  不過,發表於2010年美國臨床腫瘤協會年會的新資料顯示,接受較低劑量放射線(10-19 Gy)者也有發生乳癌高風險。
  
  紐約市Sloan-Kettering紀念癌症中心生物統計學家Chaya Moskowitz博士表示,這些婦女的乳癌風險也確實升高;值得注意的是,沒有針對這一組的篩選建議。
  
  這些研究者估計,美國約有50,000名婦女曾經使用20 Gy以上的胸部放射線治療,另外7,000-9,000人曾經使用10-19 Gy治療。
  
  Moskowitz博士解釋,胸部放射線治療後的乳癌風險已經確立;使得需曝露整個胸部的斗篷式放射線在1990年代中期停用。她在媒體簡報中表示,最近幾年,胸部放射腺所用的劑量已經降低,但是這篇研究顯示,即使是較低劑量也會使風險增加。
  
  Moskowitz博士等人分析了參與「Childhood Cancer Survivor Study (CCSS) 」研究中,童年時期患癌症而存活的1,200多名女性 ,以及參與「Women's Environmental Cancer and Radiation Epidemiology (WECARE) Study」這項研究婦女的4,570名女性一等親。
  
  整體而言,他們發現,童年時期(年齡中位數16歲)接受胸部放射線治療癌症的婦女,到了50歲時罹患乳癌的風險為24%;其中患有何杰金氏淋巴瘤的婦女(約半數研究對象)和接受過較高劑量之胸部放射線者,到了50歲時罹患乳癌的風險為30%。
  
  辛辛那提兒童醫院醫學中心Maureen O'Brien醫師參與討論該研究時表示,帶有突變者的此項風險則是31%;對於這些病患,建議處置包括雙邊預防性乳房切除術;相對的,帶有BRCA2突變的婦女,到了50歲時罹患乳癌的風險為10%;一般婦女在該年紀時的此項風險則是4%。
  
  O'Brien醫師表示,這篇研究讓我們記住的一個重要訊息是,以20 Gy作為分界點可能並不恰當。這些資料顯示10-19 Gy也有風險,這相當令人沮喪,因為目前廣泛建議使用15 Gy劑量。
  
  O'Brien醫師重提何杰金氏淋巴瘤治療時是否絕對需要使用放射線的這項爭論。她回顧資料後認為,不使用放射線的更積極化療是合理的第一線方式,只有在復發時才加入放射線。她問道:我們應該對更多病患停止使用放射線治療且接受復發率變高、然後使用救援式治療嗎?
  
  O'Brien醫師在討論中強調的其他資料顯示,目前的嚴正存活者監測並不適當。登載於JAMA (2009;301:404-414)的一篇研究發現,只有55%的童年時期癌症存活女性曾經接受過乳房攝影,而那些年紀40歲以下者,則有47%未做過該項檢查。
  
  此外,發表於會議中的一篇研究顯示,一線照護醫師一般不會依照指引照護癌症存活者。當看到一張29歲女性在16歲時進行斗篷式放射線治療何杰金氏淋巴瘤的圖片時,只有29%的一線照護醫師表示他們會進行乳癌篩檢(摘要9586),另一篇調查童年時期患癌症存活者的研究,發現不到三分之一接受以存活為重點的照護(摘要6027)。
  
  資料來源:http://www.24drs.com/professional/list/content.asp?x_logon=W&x_idno=6842&x_classno=0
  

Breast Cancer Risk in Survivors Higher Than Realized

By Zosia Chustecka
Medscape Medical News

June 4, 2012 — Among survivors of childhood cancer who were treated with radiotherapy to the chest, the risk of developing breast cancer is higher than was previously thought. New data suggest that recommendations for screening should cast a wider net to catch more of these people.

Currently, the Children's Oncology Group recommends that women who received chest radiation with 20 Gy or more be screened annually for breast cancer, using both mammography and breast magnetic resonance imaging, starting at 25 years of age or 8 years after receiving the radiotherapy.

However, new data, presented here at the 2012 Annual Meeting of the American Society of Clinical OncologyR, show that women who received lower doses of radiation (from 10 to 19 Gy) are also at high risk of developing breast cancer.

"These women also have a substantially elevated risk of breast cancer," said lead author Chaya Moskowitz, PhD, biostatistician at Memorial Sloan-Kettering Cancer Center in New York City. "It is remarkable that there is no recommendation for screening in this group," she added.

The researchers estimate that some 50,000 women in the United States have been treated with chest radiation of 20 Gy or higher, and that another 7000 to 9000 have been treated with 10 to 19 Gy.

Comparable to Risk in BRCA1 Carriers

The risk for breast cancer after chest radiation is well recognized; it led to the discontinuation in the mid-1990s of mantle radiation, which exposes the entire chest region, Dr. Moskowitz explained. The doses used for chest irradiation have been decreasing in recent years, but this study shows that even the lower doses increase the risk, she said at a press briefing.

Dr. Moskowitz and colleagues analyzed data from more than 1200 female childhood cancer survivors participating in the Childhood Cancer Survivor Study (CCSS) and 4570 female first-degree relatives of women participating in the Women's Environmental Cancer and Radiation Epidemiology (WECARE) Study.

They found that, overall, women who had received radiation to the chest for the treatment of a childhood cancer (at a median age of 16 years) had a 24% risk of having breast cancer the time they reached the age of 50.

For a subgroup of women who had had Hodgkin's lymphoma (about half of the group) and who had received higher doses of chest radiation, the risk for breast cancer was 30% by the age of 50.

This is similar to the 31% risk seen in carriers of the BRCA1 mutation; for these patients, the recommended management includes the option of bilateral prophylactic mastectomy, said Maureen O'Brien MD, from the Cincinnati Children's Hospital Medical Center in Ohio, who acted as a discussant for the study.

In comparison, women with BRCA2 mutations have a 10% risk of developing breast cancer by the time they reach the age of 50; women in the general population have a 4% risk at that age.

A critical take-home message from this study is that the cut-off point of 20 Gy might be inappropriate, Dr. O'Brien said. These data show a risk with doses in the region of 10 to 19 Gy, which is "disheartening," she said, because doses of 15 Gy are currently widely used.

Dr. O'Brien revisited the ongoing controversy of whether radiation is absolutely necessary in the treatment of Hodgkin's lymphoma. She reviewed data suggesting that more intensive chemotherapy without radiation is a reasonable first-line approach, with radiation added if necessary on relapse. She asked: "Should we eliminate radiotherapy for more patients and accept a higher relapse rate, and then use salvage therapy?"

Challenges of Survivor Care

Other data that Dr. O'Brien highlighted in her discussion suggest that current surveillance of cancer survivors is inadequate. A study published in JAMA (2009;301:404-414) found that only 55% of female childhood cancer survivors had ever had a screening mammogram, and that 47% of those younger than 40 years had never had one.

In addition, a study being presented at the meeting shows that primary care physicians, who generally end up caring for cancer survivors, are not following guidelines. When presented with a vignette of a 29-year-old woman treated for Hodgkin's lymphoma with mantle radiation at the age of 16, only 29% of the primary care physicians surveyed said they would screen for breast cancer (abstract 9586). Another study, this time surveying childhood cancer survivors, found that less than one third reported receiving survivorship-focused care (abstract 6027).

Dr. Moskowitz and Dr. O'Brien have disclosed no relevant financial relationships.

2012 Annual Meeting of the American Society of Clinical OncologyR (ASCO): Abstract CRA9513.Presented June 4, 2012.

    
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