Strategies for reducing ovarian dose in volumetric modulated arc therapy (VMAT) for postoperative uterine cervical cancer.

OBJECTIVE: To reduce the ovarian dose with volumetric modulated arc therapy (VMAT), an original VMAT was designed with two types of arcs to restrict angles and fields (R-VMAT). METHODS: The subjects were 11 patients who underwent ovarian transposition with clips left by a surgeon. Three methods, intensity-modulated radiotherapy (IMRT), standard VMAT (S-VMAT) and R-VMAT, were optimized for assessment of the ovarian dose with the target coverage kept high. RESULTS: The homogeneity and conformity indexes for the planning target volume (PTV) were similar for the three methods. However, the average ± SD of the ovarian mean dose (OMD) was 5.0 ± 1.5, 4.9 ± 1.9 and 3.5 ± 1.4 Gy, and the percentage of ovarian volume exceeding 5 Gy (V5) was 41.5 ± 34.1%, 34.1 ± 38.05% and 8.4 ± 20.5% for IMRT, S-VMAT and R-VMAT, respectively. The OMD and V5 were significantly smaller for R-VMAT than for the other plans (p < 0.01). Correlation values between the OMD and the lateral distance from the ovaries to the PTV surface were 0.86, 0.81 and 0.82 for IMRT, S-VMAT and R-VMAT, respectively. CONCLUSION: These findings suggest that R-VMAT delivered the lowest dose to the ovaries. To reduce the OMD to less than 3 Gy, ovaries should be transposed laterally 6.1 cm away from the PTV surface when R-VMAT is used. Advances in knowledge: When organs with high susceptibility to radiation, such as ovaries, are near the PTV, R-VMAT is superior to IMRT and S-VMAT.

Clinical implication of surgically treated early-stage cervical cancer with multiple high-risk factors / 부인종양

OBJECTIVE: Presence of high-risk factor in cervical cancer is known to be associated with decreased survival outcomes. However, the significance of multiple high-risk factors in early-stage cervical cancer related to survival outcomes, recurrence patterns, and treatment implications is not well elucidated. METHODS: A retrospective study was conducted for surgically treated cervical cancer patients (stage IA2-IIB, n=540). Surgical-pathological risk factors were examined and tumors expressing > or =1 high-risk factors (nodal metastasis, parametrial involvement, or positive surgical margin) were eligible for analysis (n=177, 32.8%). Survival analysis was performed based on the number of high-risk factors and the type of adjuvant therapy. RESULTS: There were 68 cases (38.4%) expressed multiple high-risk factors (2 high-risk factors: n=58, 32.8%; 3 high-risk factors: n=10, 5.6%). Multiple high-risk factors remained an independent prognosticator for decreased survival outcomes after controlling for age, histology, stage, and treatment type (disease-free survival: hazard ratio [HR], 2.34; p=0.002; overall survival: HR, 2.32; p=0.007). Postoperatively, 101 cases (57.1%) received concurrent chemoradiotherapy (CCRT) and 76 cases (42.9%) received radiotherapy (RT) alone. CCRT was beneficial in single high-risk factor cases: HRs for CCRT over RT alone for cumulative risk of locoregional and distant recurrence, 0.27 (p=0.022) and 0.27 (p=0.005), respectively. However, tumor expressing multiple high-risk factors completely offset the benefit of CCRT over RT alone for the risk of distant recurrence: HR for locoregional and distant recurrence, 0.31 (p=0.071) and 0.99 (p=0.980), respectively. CONCLUSION: Special consideration for the significance of multiple high-risk factors merits further investigation in the management of surgically treated early-stage cervical cancer.