Quantitative analysis of extracapsular extension of metastatic lymph nodes and its significance in radiotherapy planning in head and neck squamous cell carcinoma.
OBJECTIVE
We performed a histopathologic analysis to assess the extent of the extracapsular extension (ECE) beyond the capsule of metastatic lymph nodes (LN) in head and neck cancer to determine appropriate clinical target volume (CTV) expansions.


METHODS
All tumor-positive LN of 98 patients who underwent a neck dissection with evidence of ECE in at least one LN were analyzed by a single pathologist. The largest diameters of all LN, and in the case of ECE, the maximal linear distance, from the capsule to the farthest extent of tumor or tumoral reaction were recorded.


RESULTS
A total of 231 LN with ECE and 200 tumor-positive LN without ECE were analyzed. The incidence of ECE was associated with larger LN size (p < 0.001). Of all tumor-positive LN with a diameter of < 10 mm or < 5 mm, 105/220 (48%) nodes or 17/59 (29%) nodes, respectively, showed evidence of ECE. The mean and median extent values of ECE were 2 and 1 mm (range, 1-10 mm) and the ECE was < or = 5 mm in 97% and < or = 3 mm in 91% of the LN, respectively. Overall, the extent of ECE was significantly correlated with larger LN size (Spearman's correlation coefficient = 0.21; p = 0.001).


CONCLUSIONS
The incidence of ECE is associated with larger LN size. However, ECE is found in a substantial number of LN with a diameter of < 10 mm. The use of 10-mm CTV margins around the gross tumor volume seems appropriate to account for ECE in radiotherapy planning of head and neck cancer.
Ghadjar
Pirus
P
Department of Radiation Oncology, Inselspital, Bern University Hospital, and University of Bern, Freiburgstrasse, 3010 Bern, Switzerland.
Schreiber-Facklam
Heide
H
Gräter
Ruth
R
Evers
Christina
C
Simcock
Mathew
M
Geretschläger
Andreas
A
Blumstein
Norbert M
NM
Zbären
Peter
P
Zimmer
Yitzhak
Y
Wilkens
Ludwig
L
Aebersold
Daniel M
DM
D002294:Carcinoma, Squamous Cell / Q000473:pathology / Q000532:radiotherapy / Q000556:secondary* / Q000601:surgery; D005260:Female; D006258:Head and Neck Neoplasms / Q000473:pathology* / Q000532:radiotherapy / Q000601:surgery; D006801:Humans; D007012:Hypopharyngeal Neoplasms / Q000473:pathology; D007822:Laryngeal Neoplasms / Q000473:pathology; D008198:Lymph Nodes / Q000473:pathology*; D008207:Lymphatic Metastasis / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009062:Mouth Neoplasms / Q000473:pathology; D037981:Neck Dissection; D009959:Oropharyngeal Neoplasms / Q000473:pathology; D018709:Statistics, Nonparametric; D047368:Tumor Burden