Optimal radiotherapy for patients with internal mammary lymph node metastasis from breast cancer

Radiation Oncology

Table 5 Disease-free survival according to the size of the internal mammary lymph node

Characteristics		IMN size < 1.0 cm (n = 42)		IMN size ≥1.0 cm (n = 42)
Characteristics		5-year DFS	p-value	5-year DFS	p-value
Age	≤40 years	100.0%	0.009	71.3%	0.131
Age	> 40 years	77.3%		45.1%	0.131
Subtypes¹⁾	Non-TNBC	96.4%	0.031	63.5%	0.120
Subtypes¹⁾	TNBC	69.2%		47.1%	0.120
cT stages	1–2	91.1%	0.267	65.2%	0.119
cT stages	3–4	84.2%		44.4%	0.119
cN stages	2b or 3b	89.7%	0.118	56.4%	0.847
cN stages	3c	83.3%		55.6%	0.847
Malignant cells on FNABx of the IMN	(−) or	86.5%	0.327	54.5%	0.930
Malignant cells on FNABx of the IMN	unknown (+)	89.7%		58.7%	0.930
Extent of IMN	Single ICS	90.0%	0.899	57.0%	0.658
Extent of IMN	Multiple ICS	85.9%		56.0%	0.658
Neoadjuvant chemotherapy	Not performed	83.3%	0.852	40.0%	0.417
Neoadjuvant chemotherapy	Performed	89.7%		58.5%	0.417
EQD2 of the IMN²⁾	50.0–63.5 Gy	89.7%	0.932	33.3%	0.019
EQD2 of the IMN²⁾	63.6–70.4 Gy	86.4%		69.3%	0.019

¹⁾TNBC was defined as tumors that were negative for estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2 on immunohistochemical staining of the breast tumor
²⁾Radiotherapy dose was calculated using the EQD2 assuming the α/β ratio of 3.5 Gy
Abbreviations: IMN Internal mammary node, DFS Disease-free survival, TNBC Triple-negative breast cancer, FNABx Fine needle aspiration biopsy, ICS Intercostal space, EQD2 Biologically equivalent dose in 2 Gy fractions

ISSN: 1748-717X