Simultaneous or Sequential Boost to Clinically Involved Lymph Nodes in Cervical Cancer

Abstract

<h3>Purpose/Objective(s)</h3> The optimal approach to metastatic lymph nodes (LNs) in locally advanced cervical cancer (LACC) is controversial. This study aimed to evaluate the efficacy and toxicity profile of dose escalation with simultaneous integrated (SIB) or sequential boost (SB) for clinically positive LNs in LACC. <h3>Materials/Methods</h3> The data of 43 patients who underwent chemoradiotherapy (CRT) with a SIB or SB dose to positive LNs between 2015 and 2021 for LACC were retrospectively analyzed. All patients were applied 50.4 Gy intensity-modulated radiotherapy (IMRT) or modulated volumetric arc therapy (VMAT) to the lymphatic and primary regions in 28 fractions with concurrent platinum-based chemotherapy followed by 28 Gy HDR intracavitary brachytherapy (BRT) in four fractions. Response evaluations were performed via magnetic resonance imaging (MRI) and positron emission tomography (PET)-CT on the third month. <h3>Results</h3> Median age was 53 years (range: 34-80 years). The FIGO stage was IIIC1 in 30 (70%), IIIC2 in 10 (23%), and IVA in three patients (7%), respectively. Pelvic CRT was applied to 25 patients (58%), and pelvic-paraaortic CRT was applied to 18 patients (41%). A total of 94 LNs were boosted. The median longest diameter of the LNs was 1.7 cm (range: 1–7 cm) and median volume was 2.5 cc (range: 0.6-21.5 cc). A SIB was applied in 24 (56%), SB in 13 (30%), and both in 6 patients (14%), respectively. Patients in the SIB group received a total dose of 56-64 Gy in 28 fractions. The patients with SB on the other hand received 56.4-60.4 Gy in 31-33 fractions and patients with SIB+SB received 60-66 Gy in 30-32 fractions. The dose from the BRT was also calculated to the LNs and the minimum dose to LNs from BRT was between 0-7.6 Gy (median 3.6 Gy). The maximum dose from BRT was as 0-9.7 Gy (median 4.8 Gy). Median follow-up (FU) was 21 months (range: 3-77 months). Following CRT, 41 (98%) patients had a complete response (CR) and one (2%) had a partial response (PR) in boosted LNs on MRI whereas 39 (98%) patients had a CR and one (2%) had a PR on PET/CT. Recurrence occurred in 12 patients during FU: one local recurrence (LR), two regional recurrence out of the RT field, seven distant metastases (DM), and two LR+DM. There was no recurrence in any of the 94 boosted LNs and the local control (LC) rate was 100%. The 1- and 2-year rate of overall survival was 89.5% and 82.3%, disease-free survival was 80% and 65.8%, locoregional recurrence-free survival was 84.6% and 70.5%, and DM-free survival rate was 80.4% and 69.9%, respectively. Treatment was well tolerated without any serious acute toxicity. Grade 3 late toxicity was observed in two patients (1-rectovaginal fistula, 1-ureteral stenosis). <h3>Conclusion</h3> Dose escalation with IMRT/VMAT yields an excellent LC rate for the involved LNs, even for very large ones, in LACC with a low toxicity profile. Routine LN dissection may not be necessary for patients with a LACC, but prospective randomized trials are needed to clarify this.