Abstract
Background: External beam radiotherapy (EBRT) is essential in the management of locally advanced cervical cancer (LACC). Volumetric modulated arc therapy (VMAT) is thought to achieve higher conformity to the planned target volume (PTV) and better sparing of organs at risk (OAR) when compared to three-dimensional conformal radiotherapy (3D-CRT). This study focused on these principles as it applied to treatment and potential toxicity in the management of LACC. Aim: The aim of this study was to compare dosimetric parameters between VMAT and 3D-CRT in the management of LACC. Setting: The study analysed patients treated at Groote Schuur Hospital (GSH) between May and December 2017. Methods: This is a non-randomised comparative retrospective study. Three-dimensional conformal radiation and VMAT plans were generated, and data on treatment parameters for PTV D50%, Dmax, Dmean, conformity index (CI), homogeneity index (HI), treated volume (TV), irradiated volume (IV) and OAR constraints; femoral heads, bladder, bowel bag, rectum and bone marrow were collected. Results: Of the 45 patients assessed, VMAT showed statistically significant, lower treatment parameter values for CI (1.09 vs. 1.49) and TV (1613.1 cm 3 vs. 2230.3 cm 3 ), whereas 3D-CRT showed lower Dmax (48.1 Gy vs. 49.2 Gy) and IV (10652.2 cm 3 vs. 14618.1 cm 3 ). Volumetric modulated arc therapy OAR doses revealed a lower V45 for bowel bag (182.3 cm 3 vs. 411.3 cm 3 ; p < 0.001), lower V40 for bone marrow (19.1% vs. 38.7%; p < 0.001) and rectum (88.5% vs. 96%; p < 0.001). A reduced 3D-CRT dose was noted for bladder Dmax (47.4 Gy vs. 48.3 Gy; p < 0.001). Conclusion: Volumetric modulated arc therapy offered a superior dosimetric option, with better OAR dose sparing and optimal tumour dosimetry.
Highlights
Cervical cancer is the fourth most frequent cancer in women, representing 6.6% (57 000 cases) in 2018, of which 90% of deaths occurred in low- and middle-income countries.[1]
planned target volume (PTV) D2% was reviewed, which is considered a volume assigned to a maximum dose rather than a point dose, and no statistical difference was found between 3D-CRT and Volumetric modulated arc therapy (VMAT)
The data analysed for the investigated study population showed the dosimetric benefit of VMAT over 3D-CRT in the management of Locally advanced cervical cancer (LACC), with improved organs at risk (OAR) sparing
Summary
Cervical cancer is the fourth most frequent cancer in women, representing 6.6% (57 000 cases) in 2018, of which 90% of deaths occurred in low- and middle-income countries.[1]. Advanced cervical cancer (LACC) (Stage 1B2 – IVA [International Federation of Gynaecology and Obstetrics (FIGO) 2009]) is associated with a poorer prognosis with 5-year survival rates of 58% in Stage IIB, 30% in Stage III and 16% in Stage IVA.[3] Cervical cancer continues to affect middle-aged females and has been associated with numerous socio-economic factors, especially in lowermiddle-income countries.[4] Considering these factors, appropriate, beneficial, minimally toxic and proven efficacious treatment is imperative. External beam radiotherapy (EBRT) is essential in the management of locally advanced cervical cancer (LACC).
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