Department of Surgery, University Hospitals Research in Surgical Outcomes & Effectiveness Center (UH-RISES), University Hospitals Cleveland Medical Center, 11100 Euclid Ave, Cleveland, OH, 44106, USA.
Department of Radiation Oncology, University Hospitals Cleveland Medical Center, Cleveland, OH, USA.
J Gastrointest Surg. 2020 Jul;24(7):1655-1662. doi: 10.1007/s11605-020-04594-7. Epub 2020 Apr 22.
Pathologic tumor response is a prognostic factor for survival in patients with rectal cancer. Standard neoadjuvant radiation (nRT) dosing for locally advanced rectal cancer ranges from 4500 to 5400 centigray (cGy), but it is unknown if tumor regression differs as a consequence adding a boost to the tumor bed.
The National Cancer Database (NCDB) 2006-2016 was used to identify patients 18 years of age and older with clinical stage II and III rectal cancer who received pelvic nRT dosed between 4500 and 5400 cGy. Standard nRT dose (no boost, NB) and dose with boost (DWB) were defined respectively as 4500 and 5040-5400 cGy. Complete pathologic response (pCR) was defined as postoperative pathologic stage of zero. A multivariate logistic regression was performed to evaluate the association between radiation dosing and pCR.
The study cohort was 28,841 patients; the majority received DWB 22,701 (78.7%), while 6140 (21.3%) received NB. pCR was achieved in 3135 (14.4%) patients. On multivariate analysis, patients who received NB were significantly less likely to have complete tumor response (OR 1.41, 95% CI 1.2-1.66, p < 0.001). Other factors significantly associated with pCR included insurance, facility type, tumor characteristics, clinical stage, and time between radiation and surgery.
This is the first investigation demonstrating that standard dose neoadjuvant radiation for rectal cancer was associated with a lower likelihood of pCR compared with standard dose with boost. Past studies demonstrate that rectal cancer patient survival is strongly correlated with pCR. Prospective trials should focus on examining neoadjuvant radiation dosing to evaluate if DWB improves outcomes.
肿瘤病理性缓解是直肠癌患者生存的预后因素。局部晚期直肠癌的标准新辅助放疗（nRT）剂量范围为 4500 至 5400 厘戈瑞（cGy），但尚不清楚在肿瘤床添加增敏照射是否会导致肿瘤退缩程度不同。
利用国家癌症数据库（NCDB）2006 年至 2016 年的数据，确定年龄在 18 岁及以上、临床分期为 II 期和 III 期直肠癌患者，这些患者接受的盆腔 nRT 剂量在 4500 至 5400 cGy 之间。标准 nRT 剂量（无增敏，NB）和增敏剂量（DWB）分别定义为 4500 和 5040-5400 cGy。完全病理性缓解（pCR）定义为术后病理分期为零。采用多因素逻辑回归评估放疗剂量与 pCR 的关系。
研究队列包括 28841 例患者；大多数患者接受 DWB（22701 例，78.7%），6140 例（21.3%）接受 NB。3135 例（14.4%）患者达到 pCR。多因素分析显示，接受 NB 的患者完全肿瘤缓解的可能性显著降低（OR 1.41，95%CI 1.2-1.66，p<0.001）。其他与 pCR 显著相关的因素包括保险类型、机构类型、肿瘤特征、临床分期和放疗与手术之间的时间。
这是第一项表明标准剂量新辅助放疗与标准剂量加增敏照射相比，直肠癌患者发生 pCR 的可能性较低的研究。既往研究表明，直肠癌患者的生存与 pCR 密切相关。前瞻性试验应重点研究新辅助放疗剂量，以评估 DWB 是否能改善治疗效果。
