Detection of epidermal growth factor receptor mutations in lung adenocarcinoma cytological specimens by immunocytochemistry
- Masami Yoshida
- Tadasuke Nagatomo
- Takafumi Ohnishi
- Mayumi Kawashima
- Akira Naitoh
- Eiichi Morii
Published online on: October 13, 2017
Copyright: © Yoshida et al.
This is an open access article distributed under the terms of Creative Commons Attribution License.
Tyrosine kinase inhibitors of epidermal growth factor receptor (EGFR) improve the survival of patients with lung adenocarcinoma, and determine the EGFR mutation status before treatment is necessary. In contrast to biopsy samples, cytological specimens are obtained less invasively and are useful for EGFR mutation analyses. Recently, novel antibodies against two major EGFR mutations were developed: SP111, which is specific for the E746‑A750 deletion in exon 19; and SP125, which is specific for the L858R mutation. To the best of our knowledge, no study has evaluated cytological specimens using the two novel antibodies, thus their specificity and sensitivity were examined in surgical resection, and cytological lung adenocarcinoma samples in the present study. Previous screening for EGFR mutation status by molecular testing identified delE746‑A750 in 3 cases and the L858R mutation in 7 cases; the other cases did not have the L858R or the delE746‑A750 mutation. Using a four‑grade scoring system (score 0 to 3+), the immunohistochemistry (IHC) and immunocytochemistry (ICC) results were compared with those of molecular testing. Using a score of ≥2 as positive, IHC and ICC using SP111 demonstrated sensitivities of 100 and 33.3%, and specificities of 100 and 100%, respectively. IHC and ICC using SP125 revealed sensitivities of 100 and 71.4%, and specificities of 100 and 100%, respectively. Therefore, screening for EGFR mutations by ICC may facilitate therapeutic decision‑making, particularly in medical centers that are unable to perform molecular testing.