Radioisotope lymph node mapping in nonsmall cell lung cancer: can it be applicable for sentinel node biopsy?
BACKGROUND
Previous studies on intrathoracic lymph node mapping have focused on the validity of a sentinel node concept, but not on the usefulness for sentinel node biopsy.


METHODS
The subjects were 15 patients clinically diagnosed with N0 nonsmall cell lung cancer. Technetium-99m tin colloid was injected into the peritumoral area 1 day preoperatively and a time course of tracer migration was monitored by scintigraphy. A hand-held gamma probe counter was used to count the intrathoracic lymph node stations. Resected nodes were also counted to assess the accuracy of the intrathoracic counting.


RESULTS
Serial scintigraphies showed that the tracer migrated through airways and the appearance resembled hot nodes. On intrathoracic counting, 50% of the nodal stations appeared positive; however, only 23% of these apparently positive nodal stations were ultimately shown to be truly radioactive. The true positive and true negative rates of detecting intrathoracic hot nodes were 100% and 56%, respectively. Because the counts of the nodal stations could include the counts from the hot primary tumor ("shine-through") or airway radioactivity, legitimate hot nodes were identified after dissecting all the apparently positive nodal stations. Two of the 9 patients in whom hot nodes were identified had nodal metastatic disease and actually had tumor cells within the hot nodes. The only complication related to the preoperative injection of technetium-99m was a minor pneumothorax.


CONCLUSIONS
Although radioisotope intrathoracic lymph node mapping is safe, it appears to be unsuitable for sentinel node biopsy because shine-through and the airway-migrated radioactive tracer complicated the intrathoracic counting. Only serial scintigraphy could distinguish hot nodes from airway migration.
Ueda
Kazuhiro
K
First Department of Surgery, Yamaguchi University School of Medicine, Ube Yamaguchi, Japan. kaueda@yamaguichi-u.ac.jp
Suga
Kazuyoshi
K
Kaneda
Yoshikazu
Y
Sakano
Hisashi
H
Tanaka
Toshiki
T
Hayashi
Masatarou
M
Li
Tao-Sheng
TS
Hamano
Kimikazu
K
D000368:Aged; D002289:Carcinoma, Non-Small-Cell Lung / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery; D005260:Female; D015902:Gamma Cameras; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery; D008197:Lymph Node Excision; D008198:Lymph Nodes / Q000000981:diagnostic imaging* / Q000473:pathology; D008207:Lymphatic Metastasis / Q000000981:diagnostic imaging; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D011237:Predictive Value of Tests; D011379:Prognosis; D011877:Radionuclide Imaging; D021701:Sentinel Lymph Node Biopsy; D017556:Technetium Compounds; D017971:Tin Compounds
D017556:Technetium Compounds; D017971:Tin Compounds; C033493:technetium Tc 99m tin colloid