Analysis of CT-verified loco-regional recurrences after definitive IMRT for HNSCC using site of origin estimation methods

Figures & data

Figure 1. Flowchart for included HNSCC patients treated with definitive IMRT in 2006–2012.

Table 1. Patient, tumor and treatment characteristics (percentages are shown in brackets).

	CT verified loco-regional recurrences,n = 69 (%)
Age, median (range)	62 (43–81)
Sex
Male	56 (81)
Female	13 (19)
PS:
0–1	48 (70)
2–3	21 (30)
Primary tumor
Larynx	26 (38)
Oropharynx	33 (47)
Hypopharynx	6 (9)
Oral cavity	4 (6)
Tumor stage:
St. I–II	17 (25)
St. III–IV	52 (75)
p16 status in oropharynx	32
Positive	12 (37.5)
Negative	20 (62.5)
Differentiation grade:
Low/undifferentiated	20 (29)
High/moderate	46 (67)
Unknown	3 (4)
Nimorazole:
Yes	63 (91)
No	6 (9)
Treatment dose (Gy):
68	26 (38)
66	43 (62)
Fractions (per week):
6	44 (64)
5	25 (36)
Chemotherapy:
Yes	16 (23)
No	53 (77)

Figure 2. An average number of points of origin using all four methods distributed in different distances in relation to CTV1 margins. The whiskers indicate the range of the four PO methods. A: Local recurrences (LR); B: Regional recurrences (RR). Less than 0 mm defines POs inside CTV1, more than 0 mm- outside CTV1.

Figure 3. A: Loco-regional recurrences identified by A: Observer1 (1: failures in T site; 2: failures in N site); B: Centre of mass (1: failures in T site; 2: failures in N site).

Table 2. Number of recurrences relative to distance of the CTV1 surface for each of recurrence point estimates.

	All loco-regional recurrences (n = 104)
	Inside CTV1		0–4.9 mm from CTV1		5–9.9 mm from CTV1		≥10 mm from CTV1
	Amount	Covered%	Amount	Covered%	Amount	Covered%	Amount	Covered%
Obs.1	41	100	17	100	3	100	43	2
Obs.2	45	100	13	100	3	100	43	5
MSD	40	100	14	100	5	80	45	2
COM	43	100	13	100	4	100	44	5
Average (%)	42.3 (40)	100	14.3 (14)	100	15 (4)	95	43.8 (42)	3.5
T-site local recurrences, LR (n = 54)
Obs.1	28	100	13	100	2	100	11	0
Obs.2	32	100	9	100	1	100	12	8
MSD	29	100	9	100	3	100	13	8
COM	31	100	9	100	1	100	13	8
Average (%)	30 (56)	100	10 (18)	100	1.8 (3)	100	12.3 (23)	6
N-site regional recurrences, RR (n = 50)
Obs.1	13	100	4	100	1	100	32	3
Obs.2	13	100	4	100	1	100	32	6
MSD	11	100	5	100	2	50	32	3
COM	12	100	4	100	3	100	31	3
Average (%)	12.3 (25)	100	4.3 (8)	100	1.8 (4)	87.5	31.8 (63)	4

The ‘covered%’ column shows the fraction of the recurrence points covered by 95% of the prescribed (66 or 68 gy) dose. The percentage in each ‘average’ line indicates the distribution of the recurrences within each of the four groups relative to the CTV1 surface.

Obs.1: observer 1; Obs2: observer 2.