吸菸與肝臟移植後的癌症有關


  【24drs.com】根據4月號肝臟移植期刊上的研究,吸菸可以預測肝臟移植後較高的惡性腫瘤風險,而移植後戒菸可能保護這些患者免於發生腫瘤。
  
  西班牙潘普洛納納瓦拉大學醫院的主要作者J. Ignacio Herrero醫師表示,吸菸與某些常見的移植後惡性腫瘤有關,我們針對移植後戒菸與繼續吸菸之患者,研究發生惡性腫瘤的風險是否有差異。
  
  試驗作者們表示,肝臟移植後的惡性腫瘤風險是增加的,最常見的移植後癌症是頭頸部癌、肺癌、食道癌、腎臟癌與泌尿道惡性腫瘤,這幾種癌症都與吸菸有關。
  
  研究人員針對399位在1990年4月份到2009年12月份接受第一次肝臟移植且移植後存活時間大於3個月的患者進行研究,探討這些癌症的發生率與危險因子;這些患者接受cyclosporine或tacrolimus為主的免疫抑制藥物。
  
  為了評估戒菸是否與較低的惡性腫瘤風險有關,研究人員也探討135位有吸菸史患者發生與吸菸有關之腫瘤的危險因子,這些因子包括年齡、性別、肝臟移植前的酒精濫用、C型肝炎病毒感染、移植時肝細胞惡性腫瘤、以cyclosporine及tacrolimus為主要免疫抑制療程、移植後頭3個月因為排斥病史需要使用高劑量類固醇或抗淋巴球球蛋白、頭3個月的免疫抑制藥物數目以及吸菸史。
  
  在平均後續追蹤7.5年後,26位患者被診斷出29件與吸菸有關的惡性腫瘤,計算出5年與10年的精算值分別為5%與13%。根據多變項迴歸分析,與惡性腫瘤風險顯著較高的因子是吸菸和高齡。在吸菸者的次組分析中,持續吸菸與高齡是惡性腫瘤風險較高的影響變項。
  
  雖然吸菸加上免疫抑制,一般認為是移植相關惡性腫瘤的主要危險因子,但這項研究顯示較長時間的免疫抑制治療或較強的免疫抑制,與較高的癌症風險之間並沒有顯著關係。
  
  這項研究的限制包括使用吸菸作為分類變項,阻礙了決定劑量累積效應;回溯性研究設計;以及癌症事件很低,這限制了多變項分析。
  
  研究人員建議應該在較大型或多中心研究中確認這些研究結果。
  
  Herrero醫師表示,肝臟移植後戒菸可以有效地保護免於發生腫瘤。當吸菸是惡性腫瘤的重要危險因子時,結合篩檢可能可以協助降低肝臟移植患者與癌症相關的死亡率。
  
  資料來源:http://www.24drs.com/professional/list/content.asp?x_idno=6489&x_classno=0&x_chkdelpoint=Y
  

Smoking Linked to Cancer After Liver Transplantation

By Laurie Barclay, MD
Medscape Medical News

March 30, 2011 — Smoking predicted higher risk for malignancy after liver transplantation, and smoking withdrawal after transplant may protect against the development of neoplasia, according to the results of a study published online March 28 and in the April print issue of Liver Transplantation.

"Smoking is related to some of the most frequent causes of post-transplant malignancy," lead author J. Ignacio Herrero, MD, from the Clinica Universidad de Navarra in Pamplona, Spain, said in a news release. "We investigated whether the [risk] of developing malignancies was different in patients who ceased smoking than in patients who maintained smoking after transplantation."

The study authors note that risk for malignancy is increased in liver transplant recipients and that several of the most frequently experienced posttransplant cancers are head and neck, lung, esophageal, and kidney and urinary tract carcinomas, each of which is related to smoking. They studied the incidence and risk factors for the development of these cancers in 339 patients who received their first liver transplantation between April 1990 and December 2009 and who had a posttransplant survival longer than 3 months. Patients were treated with cyclosporine- or tacrolimus-based immunosuppression.

To assess whether smoking withdrawal was associated with a lower risk for malignancy, the researchers also studied risk factors for the development of smoking-related neoplasia in 135 patients who had a history of smoking. Factors studied were age, sex, alcohol abuse before liver transplantation, hepatitis C virus infection, hepatocellular carcinoma at transplantation, primary immunosuppression with cyclosporine vs tacrolimus, history of rejection requiring high doses of steroids or antilymphocytic globulins in the first 3 months, number of immunosuppressive drugs at 3 months, and smoking history.

After a mean follow-up of 7.5 years, 29 smoking-related malignancies were diagnosed in 26 patients, yielding 5- and 10-year actuarial rates of 5% and 13%, respectively. Factors independently associated with a higher risk for malignancy were smoking and older age, based on multivariate analysis. Among the subgroup of smokers, active smoking and older age were the variables associated with a higher risk for malignancy.

Although smoking in combination with immunosuppression was conventionally thought to be the main risk factor for transplant-related carcinomas, this study showed no association of longer duration of immunosuppressive treatment or stronger immunosuppression with higher risk for malignancy.

Limitations of this study include use of smoking as a categorical variable, precluding determination of a cumulative dosing effect; retrospective design; and low number of cancer events, which limited the multivariate analysis.

The investigators recommended confirming these findings in larger series or multicenter studies.

"Smoking withdrawal after liver transplantation may have a protective effect against the development of neoplasia," Dr. Herrero said. "As smoking is an important risk factor of malignancy, intervention programs, together with screening programs may help to reduce the rate of cancer-related mortality in liver transplant recipients."

The study authors have disclosed no relevant financial relationships.

Liver Transpl. Published online March 28, 2011.

    
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