Abstract
BackgroundHypofractionated whole-breast irradiation is a standard adjuvant therapy for early-stage breast cancer. This study evaluates the plan quality and efficacy of an in-house-developed automated radiotherapy treatment planning algorithm for hypofractionated whole-breast radiotherapy.MethodsA cohort of 99 node-negative left-sided breast cancer patients completed hypofractionated whole-breast irradiation with six-field IMRT for 42.56 Gy in 16 daily fractions from year 2016 to 2018 at a tertiary center were re-planned with an in-house-developed algorithm. The automated plan-generating C#-based program is developed in a Varian ESAPI research mode. The dose-volume histogram (DVH) and other dosimetric parameters of the automated and manual plans were directly compared.ResultsThe average time for generating an autoplan was 5 to 6 min, while the manual planning time ranged from 1 to 1.5 h. There was only a small difference in both the gantry angles and the collimator angles between the autoplans and the manual plans (ranging from 2.2 to 5.3 degrees). Autoplans and manual plans performed similarly well in hotspot volume and PTV coverage, with the autoplans performing slightly better in the ipsilateral-lung-sparing dose parameters but were inferior in contralateral-breast-sparing. The autoplan dosimetric quality did not vary with different breast sizes, but for manual plans, there was worse ipsilateral-lung-sparing (V4Gy) in larger or medium-sized breasts than in smaller breasts. Autoplans were generally superior than manual plans in CI (1.24 ± 0.06 vs. 1.30 ± 0.09, p < 0.01) and MU (1010 ± 46 vs. 1205 ± 187, p < 0.01).ConclusionsOur study presents a well-designed standardized fully automated planning algorithm for optimized whole-breast radiotherapy treatment plan generation. A large cohort of 99 patients were re-planned and retrospectively analyzed. The automated plans demonstrated similar or even better dosimetric quality and efficacy in comparison with the manual plans. Our result suggested that the autoplanning algorithm has great clinical applicability potential.
Highlights
Hypofractionated whole-breast irradiation is a standard adjuvant therapy for early-stage breast cancer
The mean difference between the gantry and collimator angles for F1 and F2 fields between autoplans and manual plans were 2.69 ± 3.00, 5.24 ± 5.63, 2.26 ± 2.67 and 2.42 ± 2.81 (Mean ± standard deviation (SD)) degrees, respectively
The autoplan was generally superior to the manual plan in conformity index (CI) (1.24 ± 0.06 vs. 1.30 ± 0.09, p < 0.01) and monitor unit (MU) (1010 ± 46 vs. 1205 ± 187, p < 0.01)
Summary
Hypofractionated whole-breast irradiation is a standard adjuvant therapy for early-stage breast cancer. Most patients are diagnosed at early stage without nodal involvement, and for this subgroup, the standard treatment consists of surgery and postoperative radiotherapy, and systemic adjuvant therapy if necessary. Postoperative whole-breast irradiation serves as an adjuvant therapy following breast-conserving surgery that provides equivalent long-term survival comparable to radical mastectomy, and is recognized as the standard treatment for early-stage breast cancer [2]. For node-negative patients, the hypofractionated schedule is commonly recommended as randomized trials have confirmed their safety and efficacy [3]. At our department, hypofractionated radiotherapy (42.56 Gy in 16 fractions) has been implemented for most early-stage nodenegative breast cancer patients in the recent 2 years
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