Helical tomotherapy and volumetric modulated arc therapy: New therapeutic arms in the breast cancer radiotherapy

Table 1 Definition of planning target volume

	HT	VMAT
Breast PTV	[Breast CTV + 5 mm - (PTV tumor bed + 2 mm)] - 3 mm cutaneous	[Breast CTV + 7 mm - (PTV tumor bed + 2 mm)] - 5 mm cutaneous
Tumor bed PTV	(CTV tumor bed + 5 mm) - 3 mm cutaneous	(CTV tumor bed + 7 mm) - 5 mm cutaneous
Supra infra clavicular ± axillary PTV	(CTV SN + 5 mm) - 3 mm cutaneous	(CTV SN ± axillary + 7 mm) - 5 mm cutaneous
IMC PTV	(CTV IMC + 5 mm) - PTV breast	CTV IMC + 7 mm

PTV: Planning target volume; CTV: Clinical target volume; IMC: Internal mammary chain; SN: Supra and infra clavicular nodes (Levels II-III-IV); HT: Helical tomotherapy; VMAT: Volumetric modulated arc therapy.

Table 2 Patient’s characteristics

	HT (n = 31)	VMAT (n = 42)
Age	50	52
Laterality
Right	56.8%	50%
Left	43.2%	50%
Quadrant
IQ	70.2%	40%
Outer quadrants	29.8%	60%
Size (mm)	25.4	25
N stage
N0	37.8%	21%
N1	48.6%	42%
N2	13.5%	23%
N3	0%	14%
Grade
1	2.7%	7%
2	45.9%	31%
3	51.4%	62%
LVI
-	59.5%	77%
+	40.5%	23%
Hormone receptors
RH+	76%	77%
RH-	24%	29%
Triple negative	18.9%	24%
HER2
+	16.2%	14%
-	83.8%	86%
Tobacco	16.2%	20.9%
BMI (kg/m2)	25.8	25.9
Chemotherapy
Neoadjuvant	30%	29%
Adjuvant	49%	64%
Concurrent	4%	0%
Irradiation N
SN	100%	98%
IMC	100%	100%
Axillary	16.2%	19%

HT: Helical tomotherapy; VMAT: Volumetric modulated arc therapy; BMI: Body mass index; LVI: Lymphovascular invasion; SN: Supra and infra clavicular nodes (Levels II-III-IV); IMC: Internal mammary chain; RH: Hormonal receptor; HER2: Human epidermal growth factor receptor-2; IQ: Inner quadrant.

Table 3 Doses to normal tissues

	VMAT	HT
Ipsilateral lung
V5	85.3% ± 9.6%	78.5% ± 12.6%
V20	20.1% ± 3.2%	21.1% ± 5%
V30	8.8% ± 3.2%	10.1 ± 3.3
Mean dose	13.6 ± 1.4 Gy	13.6 ± 1.2 Gy
Controlateral lung
V5	46% ± 14.1%	35.4 ± 11.3
V20	0.7% ± 0.5%	0.1 ± 0.2
Mean dose	5.4 ± 1 Gy	4.6 ± 0.8 Gy
Heart
Mean dose	10.3 ± 4.2 Gy	7.5 ± 1.4 Gy
V5	77.6% ± 21%	59.8 % ± 14.6%
V30	2.5% ± 3.9%	1% ± 1%
Controlateral breast
Mean dose	4.6 ± 0.9 Gy	3.6 ± 0.6 Gy
V5	32% ± 11.9%	14.7% ± 7%
Spinal cord
V40	0 mm3	0 mm3
V5	22.4 ± 8.8 mm3	25.2 ± 9 mm3
Oesophagus
V45	0.4 ± 0.6 mm3	1 ± 1.2 mm3
V10	8.8 ± 5.4 mm3	12.8 ± 5.7 mm3
Thyroid
Mean dose	28.3 ± 7 Gy	26.7 ± 7.7 Gy
V30	44% ± 15.3%	39.8% ± 17.6%
V5	97.1% ± 8.3%	96% ± 9.4%
Unspecified tissues
V40	1977 ± 911 mm3	1880.9 ± 754
V5	9770.3 ± 2551 mm3	8566.6 ± 1946.2

VMAT: Volumetric modulated arc therapy; HT: Helical tomotherapy.