Effect of preoperative radiotherapy with boost dose to lateral pelvic lymph node on the prognosis of patients with locally advanced rectal cancer

Abstract

Objective To evaluate the effect of preoperative radiotherapy with boost dose to lateral pelvic lymph nodes (LPN) on the prognosis of patients with locally advanced rectal cancer (LARC) treated with preoperative simultaneous chemoradiotherapy. Methods The clinical data of 116 LARC patients with complete follow-up who received adjuvant chemoradiotherapy and curative resection between March 2011 and April 2017 in Liuzhou Worker's Hospital were analyzed retrospectively. The patients were classified into two groups according to the LPN metastatic status from preoperative image: patients without suspected LPN metastasis who received preoperative simultaneous chemoradiotherapy (pelvic irradiation: 45-50.4 Gy; chemotherapy regimen: based on 5-fluorouracil) plus radical operation (the regular group, 85 cases), and patients with suspected LPN metastasis who received local boost radiation on the basis of whole radiotherapy in pelvic cavity (the boost group, 31 cases). Additional radiation boost with a total dose of 59.4-61.6 Gy to LPN was administrated to patients in the boost group. The adverse reactions of acute radiotherapy in both groups were compared by using χ2 test and Fisher exact test. Kaplan-Meier method was used to make survival analysis and Log-rank was used to make the testing. Results The common acute adverse reactions of both groups were grade 1-2 in newly adjuvant chemoradiotherapy. Significant acute adverse reactions (grade 3 or higher) in the regular group and the boost group included diarrhea [15.3% (13/85) vs. 19.4% (6/31), χ2= 0.273, P= 0.601], leukopenia [9.4% (8/85) vs. 9.7% (3/31), χ2= 0.006, P= 0.941], and radiodermatitis [4.7% (4/85) vs. 6.5% (2/31), P= 0.657]. The median follow-up time was 30.3 months (11.1-82.3 months). Locoregional recurrence occurred in 10 patients of the regular group and 4 patients of the boost group, and 16 patients and 6 patients died of the regular group and the boost group respectively. Kaplan-Meier survival results showed that there were no significant differences in local recurrence-free survival rate (χ2= 0.121, P= 0.728) and overall survival rate (χ2= 0.605, P= 0.469). Conclusion Radiotherapy boost to LPN can offset the poor prognosis of LPN metastases on patients with LARC and can be considered as a safe and effective treatment option for LARC patients with suspected LPN metastasis. Key words: Rectal neoplasms; Lateral pelvic lymph nodes; Simultaneous chemoradiotherapy; Radiation boost