乳癌的放射治療

除了手術治療，荷爾蒙治療及化學治療外，放射治療（radiotherapy）已成為乳癌治療不可或缺的一部分。是否要追加放射治療以及決定放射治療的區域，則是依據外科手術方式的不同，疾病期別以及高復發的危險因子等因素來決定。隨機臨床試驗已證實，當病人適合並同時接受乳房保留手術（breast conserving surgery）時，輔助性乳房放射治療可大幅降低局部復發機會，因此乳房放射治療是乳房保留手術後續必須的治療。同時，隨機臨床試驗和統合研究分析也證實，在較高危險機率發生局部復發機會的全乳房切除手術病人，若給予輔助性胸壁放射治療，不僅可降低局部復發機會，同時也增加病人存活率。再加上放射治療技術及軟硬體設備的進步，和逐漸使用順形放射治療和強度調控放射治療（intensity modulated radiotherapy, IMRT）等放射治療技術來治療乳癌，不僅可將放射線劑量均勻地分佈在要治療的照射目標，同時也大幅降低因放射治療所引起的副作用，例如：放射治療所引起之皮膚反應、纖維化、肺炎、手臂水腫及心血管疾病。因考慮到潛在性標準乳房放射治療的長時間療程，最近的研究主要集中於新的或其他局部治療策略，其中包括較短的體外照射治療療程，和加速部分乳房照射（accelerated partial breast irradiation, APBI）的設計，以期減少或消除較耗時的全乳房放射治療。然而，目前還不清楚哪些乳房保留手術的病人具有足夠低風險的局部復發機率，可以只接受APBI 而不需接受整個乳房照射。但有關APBI 其適應症，及長期局部控制存活率和副作用，則需等待目前正在進行的臨床隨機控制實驗結果。

In addition to surgery, antihormone therapy, and chemotherapy, radiotherapy (RT) plays an important role in the management of breast cancer. The administration of RT and the treated volume of RT for breast cancer are dependent on typing of surgery, disease stage, and high-risk factors of local recurrence. Following breast conserving surgery for early breast cancer, adjuvant breast RT significantly decreases the rate of local recurrence on the basis of the results of randomized trials. Published randomized trials and meta-analyses data have shown that postmastectomy chest wall irradiation in highest-risk patients not only decrease locoregional recurrence but also improve overall survival. Since the improvement of RT technique and RT equipment, the more use of higher conformal RT and intensity modulated radiotherapy (IMRT) for optimizing breast cancer is increasing. These results in improved target dose homogeneity, and better protection of normal tissues, with corresponding reductions in breast fibrosis, radiation pneumonitis, arm edema, and cardiovascular morbidity. In recognition of the potential longer time of standard whole breast RT, recent researches have focused on new or alternative local treatment strategies, which include shorter external beam treatment courses, and accelerated partial breast irradiation (APBI) designed to reduce or eliminate the time-consuming process of delivering whole breast RT. However, it remains unclear which patients are at sufficiently lower-risk for local recurrence to receive APBI. The long-term effectiveness and safety of APBI comparable to that of whole breast irradiation will be confirmed in recent ongoing randomized trials.