Dosimetric comparison and prognostic analysis of helical tomotherapy vs. intensity-modulated radiation therapy in locally advanced cervical cancer

Abstract

Cervical cancer is a major oncological challenge worldwide, particularly in its locally advanced stages where optimal radiotherapy strategies are essential. The present study aimed to compare the dosimetric characteristics, clinical efficacy and radiation-related toxicity of helical tomotherapy (HT) and intensity-modulated radiation therapy (IMRT) in the treatment of locally advanced cervical cancer, providing scientific evidence to optimize radiotherapy strategies. A retrospective analysis was performed using data from 100 patients with locally advanced cervical cancer treated at the Cangzhou Integrated Traditional Chinese and Western Medicine Hospital between January 2015 and December 2023. Among them, 50 patients received HT and 50 received IMRT for whole pelvic radiotherapy. Comparisons included dosimetric parameters of target areas and organs-at-risk (OARs), short-term efficacy (based on Response Evaluation Criteria in Solid Tumors 1.1), long-term outcomes [5-year overall survival (OS) and progression-free survival (PFS)] and radiation-related toxicity (graded using the Radiation Therapy Oncology Group criteria). The results revealed that HT demonstrated significantly greater conformity index and homogeneity index values compared with that of IMRT (P<0.05), with significantly reduced high-dose exposure (V₄₀ and V₅₀) to the rectum, bladder and femoral heads compared with those in the IMRT group (P<0.05). The 5-year OS was comparable between groups (72.0 vs. 68.0%; P=0.210), whilst the 5-year PFS was significantly higher in the HT group compared with that in the IMRT group (60.0 vs. 52.0%; P=0.033). The HT group also demonstrated a notably higher objective response rate (92.0 vs. 86.0%) and lower incidences of radiation-induced toxicity, particularly involving the rectum and bladder. In conclusion, HT provides marked advantages over IMRT in terms of target dose distribution, OAR protection and PFS improvement, with a favorable toxicity profile. However, further optimization is warranted to address low-dose exposure to normal tissues, as well as multicenter randomized controlled trials to validate the long-term efficacy and safety of HT.

Keywords: HT; IMRT; dosimetric comparison; locally advanced cervical cancer; survival analysis.

Figure 1.

Representative dose distribution maps for HT and IMRT plans. Dose distribution maps for the HT plan at different axial, coronal and sagittal slices. (A) Axial dose distribution, showing coverage of the planning target volume and OAR exposure, with color-coded dose gradients indicating high-dose and low-dose regions. (B) Coronal view illustrating dose homogeneity and conformity in the pelvic region. (C) Sagittal representation of dose distribution, highlighting the coverage of the cervical tumor and adjacent structures. Dose distribution maps for the IMRT plan at corresponding axial, coronal and sagittal slices. (D) Axial dose distribution showing the extent of dose conformity and differences in OAR sparing compared with HT. (E) Coronal view depicting the relative dose intensity to pelvic structures. (F) Sagittal section illustrating variations in dose deposition and tumor coverage. HT, helical tomotherapy; IMRT, intensity-modulated radiation therapy; OAR, organ-at-risk.

Figure 2.

Kaplan-Meier survival curves for all patients. (A) OS. (B) PFS. OS, overall survival; PFS, progression-free survival.

Figure 3.

Kaplan-Meier curves comparing OS and PFS between the HT and IMRT groups. (A) OS comparison. (B) PFS comparison. HT, helical tomotherapy; IMRT, intensity-modulated radiation therapy; OS, overall survival; PFS, progression-free survival.

Figure 4.

Kaplan-Meier curves comparing LCR between the HT and IMRT groups. HT, helical tomotherapy; IMRT, intensity-modulated radiation therapy; LCR, local control rate.

Figure 5.

Treatment efficacy in the HT and IMRT groups. (A) Efficacy outcomes in the HT group. (B) Efficacy outcomes in the IMRT group. HT, helical tomotherapy; IMRT, intensity-modulated radiation therapy; CR, complete response; PR, partial response; SD, stable disease; PD, progressive disease.

Figure 6.

Kaplan-Meier curves comparing OS between the HT and IMRT groups after propensity score matching. OS, overall survival; HT, helical tomotherapy; IMRT, intensity-modulated radiation therapy.

Figure 7.

Kaplan-Meier curves comparing PFS between the HT and IMRT groups after propensity score matching. PFS, progression-free survival; HT, helical tomotherapy; IMRT, intensity-modulated radiation therapy.