Simultaneous Integrated Boost Intensity-Modulated Radiation Therapy Can Benefit the Locally Advanced Rectal Cancer Patients With Clinically Positive Lateral Pelvic Lymph Node

Abstract

Background and PurposeThe optimal treatment modality for clinically positive lateral pelvic lymph node (LPLN) from locally advanced rectal cancer (LARC) is unknown. Thus, we aimed to analyze the optimal radiotherapy dose for clinically positive LPLN from LARC.Materials and MethodsWe retrospectively evaluated distal LARC (i.e., within 8 cm from the anal verge) patients with clinically positive LPLN (i.e., ≥7 mm in the short axis). They were divided into two groups based on whether or not they received simultaneous integrated boost intensity-modulated radiation therapy (SIB-IMRT)–based chemoradiotherapy. The total radiotherapy dose on LPLN were 56-60Gy for SIB-IMRT group and 41.8Gy for non-SIB-IMRT group. The clinical parameters and regrowth rate of LPLN were then compared between the two groups.ResultsA total of 151 patients were evaluated, and 83 and 68 patients were classified to the SIB-IMRT and non-SIB-IMRT group, respectively. The median follow-up period was 22.6 months, and the 2-year LPLN regrowth rate was significantly different between the SIB-IMRT group and the non-SIB-IMRT group (0% vs 10.8%, P=0.024). Further, SIB-IMRT yielded a significantly lower 2-year LPLN regrowth rate in patients whose LPLN measured ≥8 mm in the short axis (0% vs. 15.9%, P=0.019) or ≥10 mm in the long axis (0% vs. 17.6%, P=0.024) compared to patients who were in non-SIB-IMRT group. Meanwhile, there was no significant difference in grade II radiation-related toxicity (30.1% vs. 39.1%, P=0.217) and surgical complications (21.8% vs. 12.2%, P=0.198) between the two groups.ConclusionSIB-IMRT–based neoadjuvant chemoradiotherapy is beneficial for eliminating clinically positive LPLN from LARC without increasing the incidence of radiotherapy-related toxicity and surgical complications, and patients with larger LPLN may gain benefit from this technique.

Planning target volume margin assessment for online adaptive MR-guided dose-escalation in rectal cancer on a 1.5 T MR-Linac

“…Therefore, it allows smaller margins compared to non-adaptive strategies. Furthermore, we expect that the use of smaller margins in an online adaptive MRgRT setting allows for treatment intensification by increasing boost dosage on the tumor without additional OAR toxicity [32]. A change in margin size from 17 mm to 4 mm results in a substantial decrease in radiotherapy field size and irradiated healthy tissue.…”

Lateral Pelvic Nodal Management and Patterns of Failure in Patients Receiving Short-Course Radiation for Locally Advanced Rectal Cancer

“…However, our SIB approach is a novel strategy to address LPLN and stands as the first report of using a boost dose in the context of SCRT. 21 In addition, the definition of enlarged or suspicious LPLN remains somewhat variable and subject to interpretation bias across different radiologists. LLND was not performed to confirm positive LPLN status.…”

The influence of neoadjuvant chemoradiotherapy combined with lateral lymph nodes dissection or not on the local recurrence of low to intermediate‐stage II/III rectal cancer

“…This indicates that more efficient treatment options need to be explored in the future to increase the LR rate for patients with LLN enlarged. Some studies suggested that boosting the radiotherapy dose for the involved LLN arrangement from 56 to 60.2 Gy can significantly lower the SA and effectively control the LR rate for rectal cancer, while radiotherapy‐related toxicity was acceptable 31–33 . This implies that boosting the radiotherapy dose to the presumed positive lateral lymph nodes may be an effective therapy.…”