Clinical Outcome of Postoperative Intensity-Modulated Radiotherapy for Esophageal Cancer

食道癌術後接受強度調控放射治療的臨床結果

葉慧玲(Hui-Ling Yeh) ； 徐中平(Chung-Ping Hsu) ； 林進清(Jin-Ching Lin) ； 詹建勝(Jian-Sheng Jan) ； 林佳福(Jai-Fu Lin) ； 張振發(Chen-Fa Chang) ； 吳清德(Ching-Te Wu)

《放射治療與腫瘤學》 15卷4期 (2008/12) Pp. 269-278

https://doi.org/10.6316/TRO/200815(4)269

摘要

目的：評估食道癌術後的接受強度調控放射治療的臨床結果與劑量分析。
方法與材料：一共有30位stage Ⅱ-Ⅳ胸段食道癌的病人在接受治癒目的手術之後，接受了術後的放射治療。病人於術後4-6週接受放射治療，而所有的治療計畫都使用強度調控放射治療的方式。其中有7位病人同時接受了術後輔助化學治療。放射治療使用6 MV photo beam，以6-7個射束以不同的照射角度來構成CTV。CTV包含了整個原胸段食道部位，而當腫瘤位於中段／上段胸部食道時會包含鎖骨上淋巴結，而腫瘤位於下1/3食道時會包含celiac淋巴結。在5-6週的時間，PTV的劑量會給予50-60Gy。我們進而評估病人治療的反應與不良反應。
結果：放射治療所引起的急性不良反應相當輕微，而肺部，心臟與脊髓盡量避開於照射範圍；左肺與右肺所接受的平均劑量分別為13.1Gy與13.3Gy。左肺與右肺接受超過2000cGy的體積(V20)分別為19.7%與19.8%。心臟所接受的平均劑量為22.4Gy，且接受超過40Gy的體積(V40)只有9.8%。脊髓所接受的最大劑量為36.5Gy，相對來說是十分低的。平均的Conformity index為0.8，暗示治療計畫與治療標的的高度一致性，平均的homogeneity index為0.94，表示治療標的內的劑量均勻度高。在平均追蹤14個月後，有5個患者有局部復發，分布於anatomic site(1), supraclavicular region(1), subcarina region(3)。兩年的局部復發率為22.4%，而兩年的整體存活率為45.1%。遠端轉移為兩年內死亡的主要原因。
結論：胸段食道癌術後以強度調控放射治療用6-7個射束治療可以有很好的腫瘤順形度及劑量均勻度，且可以避開正常的組織。局部控制結果很好，且兩年存活率是可以接受的。然而，早期遠端轉移仍然是個治療上的問題。新的治療方式還需要去研究以期能增進臨床治療結果。

關鍵字

食道癌 ； 強度調控放射治療 ； 手術後放射治療

並列摘要

Purpose: To evaluate the clinical outcome and dosimetry analysis of postoperative intensity-modulated radiation therapy (IMRT) for esophageal cancer.
Materials and Methods: A total of 30 patients with stage Ⅱ-Ⅳ esophageal cancer were treated with curative surgery followed by postoperative radiotherapy. All postoperative radiotherapy was planned using an intensity-modulated radiotherapy (IMRT) treatment planning system and was administered 4-6 weeks after operation. Seven out of 30 patients received post-radiotherapy adjuvant chemotherapy. Radiation from 6-7 beam angles, which was designed according to specific shape of clinical target volume (CTV), was delivered by a linear accelerator with energy of 6 MV photons. The CTV included the whole esophageal region plus the supraclavicular region for tumors at the upper and middle thoracic portion of the esophagus or celiac region for tumor situated at the lower thoracic portion. A total dose of 50 Gy to 60 Gy was aimed at the PTV over 5 to 6 weeks. Treatment response was evaluated and toxicities were assessed. The organ at risk dose profile was calculated under isocenter dose of 50 Gy.
Results: Radiotherapy related acute toxicities were mild. Organs at risk such as lungs, heart, and spinal cord were spared from the prescribed doses. The mean doses for right and left lungs were 13.1 Gy and 13.3 Gy, respectively. The lung volume received doses of 2000 cGy or more (V20) for right and left lung was 19.7% and 19.8%, respectively. The mean dose to heart was 22.4 Gy and only 9.8% of heart tissue received a dosage over 40 Gy (V40). For spinal cord, the maximum dose was 36.5 Gy which is relatively low. An average conformity index (CI) of 0.8 implies high treatment conformity to the target. An average homogeneity index (HI) of 0.94 indicated good dose homogeneity within the target. After a mean follow-up of 14 months, 5 local recurrences were found over anastomotic site in 1 patient, supraclavicular region in 1 patient and subcarina region in 3 patients, the local recurrence rate in 2-year period is 22.4%. The 2-year overall survival rate was 45.1%. Distant metastasis is the most important reason for those who died within 2 year period of follow-up.
Conclusion: Postoperative IMRT using 6 to 7 beams has good coverage of the target and high dose homogeneity while decreasing doses to normal tissue. Local control was good with an acceptable 2-year survival rate. However, early distant metastasis remains to be a problem. New approaches are needed to improve the clinical outcome.

並列關鍵字

Esophageal cancer ； Intensity-modulated radiotherapy ； Post-operative radiotherapy