ESTRO 2024 - Abstract Book

S1211

Clinical - Head & neck

ESTRO 2024

than 2 years could be identified with a BA of 69.5% (p<0.05 per permutation testing), sensitivity of 70.3%, specificity of 67.9%, predictive positive value of 67.9%, and negative predictive value of 70%.

Table 1: Characteristics of the 67 reirradiated patients with a PET scan available. Characteristics Nb

%

Age (years, [median, IQR])

58 (48 – 66)

Gender Male

41 26

61.1 38.9

Female

Retreatment disease site Nasopharynx

18 16 11 11

26.9 23.9 16.4 16.4 10.4

Nodes (upper cervical neck, retropharyngeal, retrostyloid)

Oropharynx

Skull base

Hypopharynx/larynx

7 4

Oral cavity

6

Histology Squamous cell carcinoma

48 15

71.6 22.4

Undifferentiated carcinoma nasopharyngeal tumor

Adenoid Cystic Carcinoma

4

6

Time elapsed since previous irradiation (months, [median, IQR])

37 (17 - 65)

Reirradiation Techniques Intensity-Modulated Radiation Therapy Volumetric-Modulated Arc Therapy

31 17 17

49.4 25.3 25.3

Passive scattered proton therapy

Figure

1:

Principal Component Analysis (PCA) Illustrating

Second treatment course: RT total dose (Gy, [median, IQR])

66 (60 – 70)

Overall Survival (OS) OS ≥ 2 years

28 27

41.8 40.2

Overall Survival

OS < 2 years

(OS)

Group Separation in Head and Neck Cancer Patients Undergoing Reirradiation. The scatter plot suggests that patients can be separated into two distinct groups: OS ≥ 2 years and OS < 2 years mostly based on their coordinate on the first PC. Follow-up < 2 Years 12 18