Table I.

Patient characteristics.

Characteristic	Patient 1	Patient 2
Age at diagnosis, years	57	62
Primary tumor staging	cT3cN0M0	cTxcN1M0
Histology	Squamous cell carcinoma	Adenocarcinoma
Primary treatment	Chemoradiotherapy followed by surgery	Chemoradiotherapy (surgery not indicated due to comorbidities)
Disease-free interval, months	18	21
Site of recurrence	Lower neck lymph nodes	Neck lymph nodes
Number of fractions of SBRT	5	5
Dose prescribed, Gy	30	40
Prescription isodose, %	65	81
Maximum dose, Gy	45.9	49.2
Dose gradient (Paddick)	0.17	0.12
Conformity index (ICRU 83)	0.91	0.88
Maximum dose to trachea, Gy	32.6	Not applicable
Maximum dose to major blood vessels, Gy	35.4	45.7
Maximum dose to esophagus, Gy	27	Not applicable

SBRT, stereotactic body radiotherapy; ICRU, International Commission on Radiation Units.