Dosimetric risk factors for radiation esophagitis in patients with breast cancer following regional nodal radiation

Table 1 Patient characteristics

Variable	G0	G2	χ2	P value
Age
< 60	41	7	0.92	0.57
≥ 60	12	4
Laterality
Left	28	5	0.20	0.66
Right	25	6
Type of surgery
Mastectomy	40	6	1.97	0.16
Lumpectomy	13	5
Histologic type
Ductal invasive carcinoma	45	11	1.90	0.59
Lobular invasive carcinoma	3	0
Mucinous carcinoma	2	0
Others	3	0
Stage group
Ⅱ A	31	6	2.12	0.35
Ⅱ B	10	4
Ⅲ	12	1
Molecular subtype
Luminal A	18	2	6.389	0.172
Luminal B	8	0
Luminal HER2-positive	9	1
HER2 overpressing	6	2
Triple-negative	12	6
Chemotherapy
Neoadjuvant chemotherapy	19	5	0.69	0.71
Adjuvant chemotherapy	32	6
No chemotherapy	2	0
Anti-HER2 targeted therapy
No	37	9	0.65	0.66
Yes	15	3

G0: No radiation oesophagitis; G2: Grade 2 radiation oesophagitis; HER2: Human epidermal growth factor receptor 2.