Published online Aug 28, 2016. doi: 10.4329/wjr.v8.i8.735
Peer-review started: February 25, 2016
First decision: April 15, 2016
Revised: May 12, 2016
Accepted: June 27, 2016
Article in press: June 29, 2016
Published online: August 28, 2016
Processing time: 184 Days and 18.2 Hours
To analyse clinical and dosimetric results of helical tomotherapy (HT) and volumetric modulated arc therapy (VMAT) in complex adjuvant breast and nodes irradiation.
Seventy-three patients were included (31 HT and 42 VMAT). Dose were 63.8 Gy (HT) and 63.2 Gy (VMAT) in the tumour bed, 52.2 Gy in the breast, 50.4 Gy in supraclavicular nodes (SCN) and internal mammary chain (IMC) with HT and 52.2 Gy and 49.3 Gy in IMC and SCN with VMAT in 29 fractions. Margins to particle tracking velocimetry were greater in the VMAT cohort (7 mm vs 5 mm).
For the HT cohort, the coverage of clinical target volumes was as follows: Tumour bed: 99.4% ± 2.4%; breast: 98.4% ± 4.3%; SCN: 99.5% ± 1.2%; IMC: 96.5% ± 13.9%. For the VMAT cohort, the coverage was as follows: Tumour bed: 99.7% ± 0.5%, breast: 99.3% ± 0.7%; SCN: 99.6% ± 1.4%; IMC: 99.3% ± 3%. For ipsilateral lung, Dmean and V20 were 13.6 ± 1.2 Gy, 21.1% ± 5% (HT) and 13.6 ± 1.4 Gy, 20.1% ± 3.2% (VMAT). Dmean and V30 of the heart were 7.4 ± 1.4 Gy, 1% ± 1% (HT) and 10.3 ± 4.2 Gy, 2.5% ± 3.9% (VMAT). For controlateral breast Dmean was 3.6 ± 0.2 Gy (HT) and 4.6 ± 0.9 Gy (VMAT). Acute skin toxicity grade 3 was 5% in the two cohorts.
HT and VMAT in complex adjuvant breast irradiation allow a good coverage of target volumes with an acceptable acute tolerance. A longer follow-up is needed to assess the impact of low doses to healthy tissues.
Core tip: Using conventional techniques in breast and nodes irradiation, there could be suboptimal target coverage or great dose exposure to the normal structures. Our study suggests that helical tomotherapy (HT) and volumetric modulated arc therapy (VMAT) plans provide excellent target volume coverage and reduces high doses to organs at risk with an acceptable acute toxicity. At the same time, HT and VMAT deliver lower doses to larger volumes of normal tissues, suggesting in some cases an increased risk of second cancer. Nevertheless, the risk to benefit ratio seems to be in favour of HT and VMAT as opposed to three-dimensional conformal radiation therapy in complex target volumes, such as funnel chest, tumor in the inner quadrant when internal mammary chain and tumor bed boost are indicated, large breast size or unfavourable cardiac anatomy.