Efficacy and Toxicity of IMRT-Based Simultaneous Integrated Boost for the Definitive Management of Positive Lymph Nodes in Patients with Cervical Cancer

Background: The optimal radiotherapy regimen for treating metastatic lymphadenopathy in patients with locally advanced cervical cancer remains controversial. This study aimed to investigate the clinical outcomes, as well as associated toxicities, of intensity-modulated radiotherapy (IMRT) with a simultaneous integrated boost (SIB) for pelvic and para-aortic lymph nodes (LNs). Methods: Between 2011 and 2015, 74 patients with 2014 International Federation of Gynecology and Obstetrics stage IIB-IVB cervical cancer exhibiting pelvic or para-aortic LN involvement were examined. The pelvic field planning dose was 45-50 Gy in 25 fractions, and an SIB of 62.5 Gy in 25 fractions was delivered to positive LNs. Next, CT-guided brachytherapy was performed 24 Gy in 3 fractions to 42 Gy in 6 fractions once or twice weekly. Results: The median follow-up duration was 36 (range: 3-62) months. The 3-year local control, distant metastasis-free survival, and overall survival rates were 91.7%, 75.7%, and 71.4%, respectively. No residual or recurrent LNs were detected. Six patients developed grade 3 acute gastrointestinal (GI) toxicity. Twenty-nine (39.2%) and 3 (4.1%) patients developed grade 3 and 4 hematological toxicities, respectively. Twenty patients (28.5%) developed grade ≥2 chronic GI toxicity. Only 1 patient (1.4%) experienced a grade 4 rectovaginal fistula, and 3 patients (4.2%) developed grade 2 genitourinary toxicities. SIB to the LNs did not influence acute or chronic toxicity rates. Conclusions: Our findings demonstrate that a dose of 62.5 Gy to positive LNs using the IMRT with SIB method can achieve excellent clinical outcomes with acceptable toxicity.