Effect of simultaneous integrated boost intensity-modulated radiation therapy on lateral lymph node metastasis in rectal cancer / 中华放射医学与防护杂志

ABSTRACT

Objective:To evaluate the efficacy and safety of simultaneous integrated boost intensity-modulated radiation therapy (SIB-IMRT) for rectal cancer with lateral lymph node metastasis (LLNM).Methods:From January 2016 to December 2022, 103 rectal cancer patients with LLNM were enrolled. The patients were divided into SIB-IMRT group (52 cases) and conventional chemoradiotherapy (CRT) group (51 cases) using the random number table method. The dose was 50 Gy for the pelvis with 60 Gy of SIB-IMRT for the LLNM in the SIB-IMRT group. The dose was 50 Gy for the pelvis in the CRT group. The primary endpoint was the lateral recurrence rate. The efficacy and adverse reactions of the two groups were compared.Results:The adverse reactions and surgical complications after neoadjuvant radiotherapy were comparable between the two groups. The response rates of LLNM treatment were 76.9% and 56.9%, respectively, in the two groups ( χ2=4.69, P=0.03). The SIB-IMRT group and CRT group had a local recurrence rate of 7.7% and 25.5% ( χ2=5.92, P=0.015), respectively, and a lateral recurrence rate of 3.8% and 23.5% ( χ2=8.49, P=0.004), respectively. Univariate analysis showed that the SIB-IMRT, short axis of lateral lymph nodes <5 mm after radiotherapy, and negative result in the postoperative lymph node pathological examination were factors associated with lateral recurrence. Multivariable regression analysis demonstrated that the SIB-IMRT ( HR=6.42, 95% CI: 1.40-29.49) and short axis of lateral lymph nodes <5 mm after radiotherapy ( HR=0.17, 95% CI: 0.04-0.66) were independent factors associated with lateral recurrence. The two groups had a 3-year disease-free survival of 73.25% and 62.6% ( P>0.05), respectively, and a 3-year overall survival of 87% and 82.5% ( P>0.05), respectively. Conclusions:The SIB-IMRT is safe and effective for rectal cancer with LLNM. The short axis of lateral lymph nodes <5 mm after neoadjuvant radiotherapy and SIB-IMRT is an independent risk factor for lateral recurrence.