直肠癌的辅助放疗和临床研究的进展

Advances in clinical investigation of adjuvant radiotherapy in rectal cancer

手术是直肠癌治疗的主要手段。根治性手术后，局部复发的发生与原发肿瘤肠壁侵润的深度和淋巴结转移直接相关，也是直肠癌最常见的治疗失控部位。早期临床研究提示T1-2N0M0的局部失败率低于10％，T3N0M0和T1N1M0的局部失控在15％～35％，T3-4N1-2M0则可达45％-65％。尽管远处转移是治疗失败的重要原因，但主要原因却是局部复发，这也是在可切除直肠癌治疗中采用辅助治疗的理由。随机临床研究已证实辅助放疗联合化疗的综合治疗，较单纯手术或术后单纯放疗可显著提高肿瘤的局部控制。放疗在直肠癌综合治疗中的目标是：提高局控，增加保肛的机率和功能，提高生存率及生活质量。对临床可切除的肿瘤，辅助放疗的模式主要有两种：一种为先手术，如肿瘤为T3和（或）N1-2，再接受术后的联合治疗；另一种为术前的联合治疗，放疗或放化疗，然后手术。术前放疗（或放化疗）的优点为减少术中种植；肿瘤退缩、分期降低从而增加肛门括约肌保留的机会；肿瘤细胞富氧，对放射较敏感；放射治疗的毒性反应较小。

Surgery has remained the mainstay of treatment of rectal cancer but due to high local recurrence rates, adjuvant chemoradiation has become standard practice for advanced rectal cancer. In 1990, postoperative chemoradiation has been established by NCI based on the results of GITSG, NCCTG and intergroup studies. However, the German CAO/ ARO/AIO 94 study showed that preoperative chemoradition is better than postoperative in terms of local control and acute toxicity. The 5-year cumulative incidence of local relapse was lower in patients assigned to pre-operative chemoradiation vs postoperative treatment Grade 3 or 4 acute toxic effects occurred in 27% of patients in pre-op group vs 40% in post-op group. The corresponding rates of long-term toxic effects were 14% and 24%, respectively. Preoperative chemoradiation has been the trend of treatment of advanced rectal cancer.