The impact of induction chemotherapy on the dosimetric parameters of subsequent radiotherapy: an investigation of 30 consecutive patients with locally-advanced non-small cell lung cancer and modern radiation planning techniques

Radiation Oncology

Table 3 Median values for dosimetric variables derived from scans obtained before and after induction chemotherapy

	All patients (n = 30)			RECIST responders (n = 5)			RECIST stable and progressive (n = 25)			Pre-ICT GTV >100 cc ³ (n = 21)			Pre-ICT GTV ≤100 cc ³ (n = 9)
Variable	Pre-ICT	Post-ICT	P*	Pre-ICT	Post-ICT	P*	Pre-ICT	Post-ICT	P*	Pre-ICT	Post-ICT	P*	Pre-ICT	Post-ICT	P*
GTV size, cm³	117	111	0.02	117	62	0.04	115	115	0.14	134	126	0.04	57	40	0.26
CTV size, cm³	344	297	0.03	350	218	0.04	338	338	0.22	372	379	0.03	193	160	0.86
PTV size, cm³	546	559	0.37	617	376	0.04	528	574	0.76	606	621	0.22	312	342	0.51
GTV₉₅, %	100	100	0.73	100	100	0.32	100	100	0.99	100	100	0.74	100	100	0.32
CTV₉₅, %	100	100	0.15	100	100	0.40	100	100	0.23	100	100	0.36	100	100	0.40
PTV₉₅, %	96.7	96.1	0.31	98.6	99.1	0.89	96.5	94.8	0.26	96.5	95.0	0.43	97.0	97.3	0.37
Lung V₅, %	50.5	51.8	0.31	50.0	51.2	0.14	50.5	52.6	0.68	52.5	52.2	0.20	50.0	51.2	0.95
Lung V₂₀, %	29.1	28.9	0.24	29.3	26.3	0.04	28.9	29.6	0.86	29.5	29,6	0.61	27.9	27.9	0.11
Lung mean dose, Gy	18.1	18.5	0.45	18.2	16.4	0.04	18.1	18.6	0.68	18.2	18.5	0.96	16.1	18.6	0.11
Esophagus mean dose, Gy	28.2	28.4	0.24	26.7	24.0	0.89	28.7	28.4	0.20	31.4	32.3	0.42	22.2	22.2	0.44
Esophagus max, Gy	74.3	76.5	0.56	68.9	67.3	0.22	75.2	76.6	0.27	75.2	76.4	0.97	73.3	76.6	0.21
Esophagus V₅₀, %	29.0	28.9	0.08	32.4	20.9	0.22	28.9	30.1	0.02	32.1	31.7	0.10	23.8	23.5	0.34
Heart mean dose, Gy	11.1	11.3	0.29	6.3	6.0	0.22	12.6	13.3	0.49	12.6	15.4	0.43	6.6	10.2	0.44
Heart V₄₀, %	8.6	7.0	0.63	4.6	3.5	0.17	9.4	8.84	0.86	11.2	10.8	0.70	3.5	6.8	0.50
Spinal cord max, Gy	42.3	42.7	0.19	42.7	41.7	0.5	42.3	42.8	0.25	42.8	43.1	0.33	39.2	41.7	0.37

Abbreviations: GTV gross tumor volume, CTV clinical target volume, PTV planning target volume.
*P values calculated with Wilcoxon matched-pairs signed-ranks test. Bolded p values are <0.05 and are taken as statistically significant.