Abstract
BACKGROUND: To evaluate whether the use of the internal target volume (ITV) delineation method improves the performance of intensity-modulated radiotherapy (IMRT) and three-dimensional conformal radiotherapy (3DCRT) in terms of survival, acute toxicities, and dose-volume parameters. METHODS: A total number of 477 cervical cancer patients who received concurrent chemoradiotherapy (CCRT) from January 2012 to December 2016 were retrospectively analyzed. They were divided into four groups: the non-ITV (N-ITV) + IMRT, ITV + IMRT, N-ITV + 3DCRT, and ITV + 3DCRT groups, with 76, 41, 327, and 33 patients, respectively. Survival analysis was performed with the Kaplan-Meier and the log-rank tests, and acute toxicity analysis was performed with the chi-squared test and the binary logistic regression test. Using the propensity score matching (PSM) method, 92 patients were matched among the four groups, and their dose-volume parameters were assessed with the Kruskal-Wallis method. RESULTS: The median follow-up time was 49 months (1-119) for overall survival (OS). The 5-year OS rate was 66.4%. The ITV delineation method was an independent prognostic factor for OS (HR [95% CI]: 0.52 [0.27, 0.98], p = 0.044) and progression-free survival (PFS) (HR [95% CI]: 0.59 [0.36, 0.99], p = 0.045). The ITV + IMRT group had the lowest incidence rate (22%) and the N-ITV + IMRT group had the highest incidence rate of grade ≥3 hematological toxicity (HT) (46.1%) among the four groups. The pelvic bone marrow relative V10, V20, and V30 in the N-ITV + IMRT group was higher than those in the ITV + IMRT and N-ITV + 3DCRT groups (p < 0.05). CONCLUSIONS: The use of ITV for IMRT treatment planning was associated with improved overall survival and progression-free survival, with lower HT rate.