the current standard of care for patients with locally advanced non - small cell lung cancer ( nsclc ) is concurrent chemoradiotherapy ( crtx ) or surgery with crtx ; however , the most effective treatment for patients with locally advanced ( stage iii ) nsclc remains controversial . when concurrent crtx followed by surgery is performed , patients with a pathological complete response tend to show a longer overall survival than those without a pathological complete response [ 1 , 2 ] . epidermal growth factor receptor ( egfr)-tyrosine kinase inhibitors ( tkis ) are effective against more than 70% of advanced nsclc with egfr gene mutations [ 3 , 4 , 5 ] . some authors have reported the usefulness of surgical resection after gefitinib treatment for responding patients [ 6 , 7 , 8 ] . however , almost all the reported patients who underwent surgical resection after gefitinib treatment had distant metastasis . in this report , we describe a patient in whom the pathological effect was a slight pathological response ; however , she had a partial response ( pr ) after gefitinib treatment for nsclc harboring an egfr gene mutation . a 66-year - old female never - smoker with no significant medical history was referred to our hospital for the evaluation of an abnormal shadow observed on a chest x - ray film . chest computed tomography ( ct ) revealed a 4.4-cm primary mass in the left upper lobe beside the main pulmonary artery and the growth of mediastinal lymph nodes ( ct2an2m0 stage iiia ) ( fig . fluorodeoxyglucose positron emission tomography ( fdg - pet ) showed fdg uptake in the mass with a maximal standardized uptake value ( suv ) of 12.2 , and in mediastinal lymph nodes with an suv of 6.6 ( fig . the l858r mutation in exon 21 of the egfr gene was identified in the primary lung tumor . we gave the patient and her family three possible treatment options : concurrent crtx ( using standard platinum - based doublet chemotherapy ) , induction chemotherapy followed by surgery , or gefitinib therapy . therefore , systemic chemotherapy with gefitinib ( 250 mg / body ) was performed . after 3 months of gefitinib treatment , a radiological ct evaluation revealed that there was a pr to gefitinib ( regression rate was 35% ) ( fig . 1d , e ) , and a pet scan image showed positive accumulation of fdg ( suv max . 1f ) . because of the good response , the patient wanted to undergo surgery . the gefitinib administration was stopped 2 weeks prior to surgery so that the drug would not interfere with tissue repair . we performed a left upper lobectomy and a combined resection of s6 , which was involved by the tumor , and a systematic lymphadenectomy . because the initially swollen lymph nodes had become thickened fibrous scars owing to the response to gefitinib , it was difficult to expose the superior trunk of the pulmonary artery . finally , complete resection was achieved . the pathological examination revealed adenocarcinoma in the primary site , hilar lymph node ( # 12u ) and mediastinal lymph node ( # 5 ) , which also involved extra nodal disease . the tumor size was 37  32  30 mm , and the left s6 was considered to have higher than interlobar involvement ( pt2an2m0 stage iiia ) . the pathologically therapeutic effect was considered to be slight or of no response ( fig . egfr t790 m mutation and met amplification , which are often acquired following gefitinib treatment , were not observed . ten months after the operation , the patient developed recurrence in the cervical lymph nodes and multiple pulmonary metastases . gefitinib therapy was tried again , and the effect was a pr of the lymph nodes and complete response of the pulmonary metastases . she is doing well and is still being treated with gefitinib , 16 months after surgery . generally , when preoperative therapy is considered to have achieved a good response , the pathological effect is a moderate or complete pathological response . when induction therapy is performed , pathological downstaging and a pathological complete response are independent factors for a favorable overall survival [ 1 , 2 ] . some large - scale studies have been previously reported regarding preoperative egfr - tki in patients with early - stage nsclc [ 10 , 11 , 12 , 13 ] . one such study mentioned the pathological response , but the clinical response did not clearly correlate with the pathological response in detail . in addition , no large - scale studies have thus far been reported regarding the use of preoperative egfr - tki in patients with advanced ncslc . there have been a few reports regarding the association between the clinical response after induction therapy and the pathological effect after surgery in advanced ncslc . nine of these patients harbored egfr gene mutations , and 4 of them had a known pathological effect . all 4 of these patients had a pr to induction therapy in the clinical images , and 3 out of the 4 had a complete pathological response , while 1 had a moderate pathological response [ 6 , 7 , 8 ] . in this report , there was a discrepancy between the clinical image and pathological findings in an nsclc patient , harboring an egfr gene mutation , who underwent surgical resection after gefitinib treatment . it is possible that the pathological effect after egfr - tki treatment might be overestimated . in fact , of the previously reported 4 cases , 3 were short - term outcomes , and 1 patient developed recurrence in the brain 2 years and 4 months after surgery [ 6 , 7 , 8 ] . in conclusion , surgery following induction therapy using egfr - tki should be carefully considered , even if the nsclc harbors an egfr gene mutation and the clinical imaging shows a complete clinical response .
we herein describe a discrepancy between the clinical image and pathological findings in a non - small cell lung cancer patient with an epidermal growth factor receptor ( egfr ) mutation who underwent surgical resection after gefitinib treatment . 
 the patient was a 66-year - old female with c - stage iiia lung adenocarcinoma harboring an egfr gene mutation ; she was surgically treated after receiving gefitinib . 
 the pathological examination revealed adenocarcinoma , and the pathologically therapeutic effect was considered to be slight or of no response . 
 egfr t790 m mutation and met amplification were not present . 
 the pathologically therapeutic effect is generally well correlated with the response rate after induction therapy . in this case , there was a discrepancy between the clinical image and pathological findings . 
 our findings , therefore , raise questions about the role of surgery after egfr - tyrosine kinase inhibitor treatment .