Table 1.
Risk factors of radiation-induced subcutaneous fibrosis
| Grade <2 RISF (N = 116) | Grade ≥2 RISF (N = 5) | P value | |
|---|---|---|---|
| Patients' characteristics | |||
| Median age, years (range) | 62 (45−82) | 60 (51−71) | 0.355 |
| BMI (overweight and obese; number of patients) | 59 | 3 | 0.689 |
| Bra size (large, number of patients) | 81 | 3 | 0.572 |
| Smokers (number of patients) | 11 | 1 | 0.441 |
| Diabetes mellitus/hypertension (number of patients) | 39 | 2 | 0.768 |
| Volume of surgical specimen, cm3 (median) | 53.2 | 65.5 | 0.333 |
| Tumour volume, cm3 (median) | 3.03 | 0.43 | 0.078 |
| ER−/PR+ | 24 | 1 | 0.188 |
| ER+/PR− | 4 | 1 | |
| ER+/PR+ | 88 | 3 | |
| RILA, % (median) | 13 | 6.9 | 0.019 |
| Treatment planning | |||
| Mean lung dose, Gy (median) | 5.2 | 9.7 | 0.007 |
| Lung V20, Gy (median) | 8.4 | 19.5 | 0.008 |
| Lung V30, Gy (median) | 7.2 | 15.1 | 0.013 |
| Mean breast cutaneous dose, Gy (median) | 41.9 | 35.9 | 0.126 |
| Dosimetric breast volume, cm3 (median) | 728.7 | 701.1 | 0.641 |
BMI, body mass index; ER, oestrogen receptor; PR, progesterone receptor; RISF: radiation-induced subcutaneous fibrosis.