Significance of ovarian transposition in the preservation of ovarian function for young cervical cancer patients undergoing postoperative volumetric modulated radiotherapy

BACKGROUND: This paper aimed to evaluate the effectiveness of ovarian transposition (OT) and the dose constraint for preserving ovarian function in young cervical cancer patients who underwent postoperative volumetric modulated arc therapy (VMAT). METHODS: A retrospective analysis was conducted of young cervical cancer patients who accepted postoperative VMAT in the Affiliated Cancer Hospital of Nanjing Medical University from September 2015 to September 2018. VMAT plans for OT and non-OT patients were compared, and the patients’ ovarian function was followed up. The transposed position of the ovaries and the radiation dose constraint were further explored using a receiver operator characteristic (ROC) curve. RESULTS: A total of 51 young patients (age ≤40 years) were included in the study, 32 of whom underwent OT and 19 of whom did not. For these OT and non-OT patients, the homogeneity index (HI), conformity index (CI), organs at risk (OARs), average number of monitor units (MUs), and mean treatment time were similar and showed no statistically significant difference (P≥0.05). Through follow-up studies, the number of patients with preserved ovarian function was found to be 22 (out of 32) and 0 (out of 19) in the OT and non-OT patients, respectively. The minimal distance for preserving ovarian function was determined as 2.1 cm between the center of a transposed ovary and the planning target volume (PTV) margin. The optimal limited radiation doses were estimated as maximum dose (D(max)) 9.8 Gy and mean dose (D(mean)) 4.6 Gy, respectively. CONCLUSIONS: OT shows no negative effects on dose distribution, target region conformity, protection of OARs, or treatment efficacy and is therefore a reliable method in the preservation of ovarian function for young cervical cancer patients undergoing postoperative radiotherapy using the VMAT technique. Specifically, when the distance between the center of a transposed ovary and the PTV margin is more than 2.1 cm, and the radiation dose is limited to a D(max) of less than 9.8 Gy and a D(mean) of less than 4.6 Gy, the function of transposed ovaries may be preserved.