New dose constraint reduces radiation-induced fatal pneumonitis in locally advanced non-small cell lung cancer patients treated with intensity-modulated radiotherapy

Figures & data

Table I. Patients characteristics.

Patients (n)	IMRT-1 (37)	IMRT-2 (50)
Age (years) median (range)	66 (47–81)	69 (44–84)
Sex
Male	20	33
Female	17	17
Performance status WHO
0–1	35	37
2	2	13
Pre-existing COLD
Yes	13	13
No	24	37
Chemotherapy
Neo-adjuvant	18	20
Concurrent	16	25
No	3	5
Co-morbidity
Yes	29	37
No	8	13
FEV1 (L) median (range)	2.2 (1.2–3.6)	1.9 (0.9–4.5)

COLD, chronic obstructive lung disease; FEV1, forced expiratory volume in the first second; IMRT, intensity-modulated radiotherapy.

Figure 1. Actuarial analysis of the incidence of radiation pneumonitis (RP) in IMRT-1 with V20 ≤ 40% or V20 ≤ 40% + MLD ≤ 20 Gy (dotted line), in comparison with IMRT-2 (solid line) with V20 ≤ 40% MLD Gy ≤ 20 Gy and V5 ≤ 60%. A) For RP grade ≥ 3 (ns). B) Fatal RP grade 5 (p = 0.05).

Figure 2. Mean dose volume histogram (DVH) for the lung in the three implementation phases with different dose constraints. Each curve is the average DVH of 12 patients (phase I), 25 patients (phase II) and 50 patients (phase III). The lung volume receiving low doses < 20 Gy, significantly decreased from 51 ± 2% in phase I and II to 41 ± 1% in phase III (p < 0.0001).

Figure 3. Histogram of percentage of lung volumes receiving low doses ranging from 0 to 20 Gy in patients of the three implementation phases of IMRT. The mean low dose volume in phase I is 52.2% (SEM 4.2), in phase II 50.1% (SEM 2.8) and in phase III 41.1% (SEM 1.3).

Figure 4. The MLD and V5 in all patients. Each symbol represents one patient. The shape of the symbols indicates the grade of RP. The reference lines are the two new constraints of V5 and MLD.