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Table 1 Patient characteristics

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

Characteristics Number of patients (%)
Age (years)≤4038 (45.2%)
 > 4046 (54.8%)
Laterality of breast cancerLeft breast57 (67.9%)
 Right breast27 (32.1%)
Location of breast cancerInner or center part66 (78.6%)
 Outer part18 (21.4%)
Histologic typeInvasive ductal carcinoma78 (92.9%)
 Others6 (7.1%)
Histologic grade1–245 (53.6%)
 330 (35.7%)
 Unknown9 (10.7%)
Tumor subtypeER+/or PR+/HER2-32 (38.1%)
 ER+/or PR+/HER2+12 (14.3%)
 ER−/PR−/HER2+10 (11.9%)
 ER−/PR−/HER2-30 (35.7%)
cT stageT1-T247 (56.0%)
 T3-T437 (44.0%)
cN stageN2b or N3b63 (75.0%)
 N3c21 (25.0%)
Extent of IMNSingle ICS37 (44.0%)
 Multiple ICS47 (56.0%)
Long diameter of the IMN< 1.0 cm42 (50.0%)
 ≥1.0 cm42 (50.0%)
Type of breast surgeryBreast-conserving surgery40 (47.6%)
 Mastectomy44 (52.4%)
Type of axillary surgerySentinel lymph node biopsy10 (11.9%)
 Axillary lymph node dissection74 (88.1%)
Neoadjuvant chemotherapyPerformed66 (78.6%)
 Not performed18 (21.4%)
EQD2 of the IMN1)50.0–63.5 Gy35 (41.7%)
(median, 63.6 Gy; range, 50–70.4 Gy)63.6–70.4 Gy49 (58.3%)
  1. 1)Radiotherapy dose was calculated using the EQD2 assuming the α/β ratio of 3.5 Gy. Abbreviations: IDC Invasive ductal carcinoma; ER Estrogen receptor, PR Progesterone receptor, HER2 Human epidermal growth factor receptor type 2, ICS Intercostal space, IMN Internal mammary node, EQD2 Biologically equivalent dose in 2 Gy fractions