Late effects arising from volumetric modulated arc therapy to the breast: A systematic review

Volumetric modulated arc therapy (VMAT) to the breast offers the potential for excellent dose conformity with the possibility of integrating a simultaneous boost within the treatment plan. This technique, however, also delivers a low dose to a large amount of healthy tissue. This systematic review aimed to determine if VMAT offers a clinically significant difference in late effects compared with conformal radiotherapy techniques for breast radiotherapy. A systematic review and quality appraisal of primary studies evaluating VMAT to the breast was performed, adopting the PRISMA checklist. A total of 8 studies were included in the review. These demonstrated variation in prescription, outcome measures and cohort characteristics. Findings supported the value of VMAT for reducing organ at risk (OAR) doses but also confirmed the potential secondary cancer risk arising from the low dose bath. Hybrid techniques combining VMAT with tangential intensity modulated or standard radiotherapy showed promise when tangential plans failed to meet objectives. VMAT alone does not offer any significant benefit to late effects over conventional for breast radiotherapy due to the creation of a low dose bath, despite improving OAR doses. More research into hybrid techniques is warranted to identify the most appropriate treatment for different patient subgroups and tumour locations. VMAT may not be the optimal technique for breast radiotherapy; hybrid plans combining tangential IMRT with VMAT are recommended.