Ahmad N R, Marks G, Mohiuddin M
Department of Radiation Oncology and Nuclear Medicine, Thomas Jefferson University Hospital, Philadelphia, PA 19107.
Int J Radiat Oncol Biol Phys. 1993 Nov 15;27(4):773-8. doi: 10.1016/0360-3016(93)90448-5.
A variety of dose-time schedules are currently used for preoperative radiation therapy of rectal cancer. An analysis of patients treated with high-dose preoperative radiation therapy was undertaken to determine the influence of radiation dose on the patterns of failure, survival, and complications.
Two hundred seventy-five patients with localized rectal cancer were treated with high-dose preoperative radiation therapy. One hundred fifty-six patients received 45 Gy, +/- 10% (low-dose group). Since 1985, 119 patients with clinically unfavorable cancers (fixed, low-lying, or deeply ulcerated) were given a higher dose, 55 Gy, +/- 10%, using a shrinking field technique (high-dose group). All patients underwent curative resection. Median follow-up was 66 months in the low-dose group and 28 months in the high-dose group. Patterns of failure, survival, and complications were analyzed as a function of radiation dose.
Fourteen percent (38/275) of the total group developed a local recurrence; 20% (31/156) in the low-dose group as compared with 6% (7/119) in the high-dose group. The actuarial local recurrence rate at 5 years was 20% for the low-dose group and 8% for the high-dose group, and approached statistical significance with p = .057. For tethered/fixed tumors the actuarial local recurrence rates at 5 years were 28% and 9%, respectively, with p = .05. Similarly, for low-lying tumors (less than 6 cm from the anorectal junction) the rates were 24% and 9%, respectively, with p = .04. The actuarial rate of distant metastasis was 28% in the low-dose group and 20% in the high-dose group and was not significantly different. Overall actuarial 5-year survival for the total group of patients was 66%. No significant difference in survival was observed between the two groups, despite the higher proportion of unfavorable cancers in the high-dose group. The incidence of complications was 2%, equally distributed between the two groups.
High-dose preoperative radiation therapy for rectal cancer results in excellent local control rates. However, in clinically unfavorable cancers a higher dose (55 Gy) of preoperative radiation can be given safely with significantly improved local control. Careful clinical staging is helpful in selectively treating patients with unfavorable tumors to a higher preoperative radiation dose and thus optimizing their outcome.
目前直肠癌术前放射治疗采用多种剂量 - 时间方案。对接受高剂量术前放射治疗的患者进行分析，以确定放射剂量对失败模式、生存率和并发症的影响。
275例局部直肠癌患者接受了高剂量术前放射治疗。156例患者接受45 Gy，±10%（低剂量组）。自1985年以来，119例临床情况不佳的癌症患者（固定、低位或深度溃疡）采用缩野技术给予更高剂量55 Gy，±10%（高剂量组）。所有患者均接受了根治性切除。低剂量组的中位随访时间为66个月，高剂量组为28个月。根据放射剂量分析失败模式、生存率和并发症。
全组中有14%（38/275）发生局部复发；低剂量组为20%（31/156），而高剂量组为6%（7/119）。低剂量组5年精算局部复发率为20%，高剂量组为8%，p = 0.057，接近统计学显著性。对于固定/粘连性肿瘤，5年精算局部复发率分别为28%和9%，p = 0.05。同样，对于低位肿瘤（距肛管直肠交界处小于6 cm）复发率分别为24%和9%，p = 0.04。低剂量组远处转移的精算率为28%，高剂量组为20%，无显著差异。全组患者总体5年精算生存率为66%。尽管高剂量组中不良癌症的比例较高，但两组之间在生存率方面未观察到显著差异。并发症发生率为2%，在两组中分布均匀。
直肠癌高剂量术前放射治疗可实现出色的局部控制率。然而，对于临床情况不佳的癌症，给予更高剂量（55 Gy）的术前放射治疗可安全进行，且局部控制有显著改善。仔细的临床分期有助于选择性地对不良肿瘤患者给予更高的术前放射剂量，从而优化其治疗结果。
