Cyclin-dependent kinase (CDK) 4/6 inhibition in non-small cell lung cancer with epidermal growth factor receptor (EGFR) mutations.

BACKGROUND: Lung cancer is the leading cause of cancer death worldwide, and EGFR mutation is the most common genetic alteration among Asian patients with lung adenocarcinoma. While osimertinib has been shown to be effective in lung cancer patients with EGFR mutation, the majority of patients eventually develop acquired resistance to treatment. We explored the significance of the cyclin D1 expression in patients with EGFR mutation and the potential efficacy of adding abemaciclib, a cyclin-dependent kinase (CDK) 4/6 inhibitor, simultaneously with osimertinib in vitro. MATERIALS AND METHODS: Immunohistochemical staining, using an anti-cyclin D1 antibody, of specimens from 83 patients with EGFR mutation (male, n = 27; pStage 0-I, n = 71) who were treated by surgical resection between 2017 and 2020, and the relationship between the cyclin D1 expression and clinicopathological factors was analyzed. Additionally, the combined effect of osimertinib and abemaciclib in lung cancer cell lines were analyzed using a growth inhibition test, and the signaling pathway underlying the combined effect was investigated. RESULTS: Cyclin D1 was negative in 18.1% of patients with EGFR mutation, and cyclin D1 negativity was associated with pStage ≥ II (p = 0.02), lymph node metastasis (p = 0.001), and lymphatic invasion (p = 0.01). The cyclin D1-negative group had significantly shorter recurrence-free survival (p = 0.02), although this difference disappeared when limited to pN0 patients. In EGFR mutated cell lines, the combination of osimertinib and abemaciclib demonstrated synergistic effects, which were thought to be mediated by the inhibition of AKT phosphorylation. CONCLUSION: Combination therapy with CDK4/6 inhibitors and EGFR-TKIs may be a promising approach.

Acquired resistance to an epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI) in an uncommon G719S EGFR mutation.

Background Acquired resistance (AR) to an epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI) is a common event, and several underlying mechanisms, including T790 M, MET amplification and PTEN downregulation, have been reported for the common EGFR mutations. EGFR G719X is an uncommon mutation that has been reported to show sensitivity to EGFR-TKIs. However, no established cell lines harboring the EGFR G719X have been reported in the literature. Materials and Methods G719S-GR cells were established from malignant pleural effusion of a patient whose tumor developed AR from gefitinib treatment. G719S-GR cells were then genotyped and tested for drug sensitivities. Multiplex ligation-dependent probe amplification (MLPA) was used to compare the clinical tumor samples with G719S-GR. Results G719S-GR cells were resistant to EGFR-TKIs with an LC50 of around 10 µM. A genomic analysis showed that G719S-GR cells harbor the EGFR G719S mutation as well as the amplification of EGFR locus. The homozygous deletion of CDKN2A and the loss of PTEN and TSC1 were also detected. On comparing the copy number of tumor suppressor genes using MLPA, G719S-GR cells were found to lack one copy of PTEN, which was not observed in a tumor obtained before gefitinib treatment. Loss of PTEN may result in AKT activation. The mTORC1/2 inhibitor Torin-1 was able to inhibit the downstream signaling when combined with osimertinib. Discussion The newly established G719S-GR cell line may be useful for investigating the mechanism underlying the development of AR in the G719X mutation; the loss of PTEN may be one such mechanism.

Challenges in Robotic Lung Lobectomy through the Anterior Approach.

PURPOSE: Robot-assisted thoracic surgery (RATS) has become popular because of its minimally invasive nature and reduced burden on surgeons. The anterior approach (AA) is beneficial because it utilizes the same field of view and procedures as thoracotomy and video-assisted thoracic surgery, although the disadvantages are less well-known. METHODS: We retrospectively examined 35 consecutive patients who underwent RATS lobectomy via the AA, focusing on clinical factors and postoperative complications. RESULTS: The study included 12 males and 23 females with a median console time of 177 (120-346) min, median blood loss of 0 (0-100) mL, and median stapler usage of 5 (2-10) units. Postoperative complications, classified as Clavien-Dindo grade ≥III, included three cases of grade IIIa (prolonged air leakage) and one case each of grade IIIb and grade IVa (middle lobe torsion and ventricular arrhythmia). The influence of stapling device operation cannot be ruled out in prolonged air leakage and middle lobe torsion. A moderate correlation (correlation coefficient = 0.492, p = 0.003) was observed between console time and the number of staplers used. CONCLUSION: Although no severe incidence of vascular injury was observed with the AA, complications related to the use of stapling devices were noted.

EGFR-mutated lung adenocarcinoma with choroidal oligometastasis during treatment with gefitinib: a case report.

The patient was a 74-year-old woman who was diagnosed with lung adenocarcinoma, clinical Stage IIIA. Induction chemoradiation was performed followed by right upper lobectomy and lymph node dissection. Because of positive pleural effusion cytology, which was proven after surgery, the patient was diagnosed with pathological Stage IVA with EGFR L858R mutation. At 17 months after the administration of gefitinib, left choroidal metastasis appeared. Stereotactic irradiation and ruthenium small-beam radiation were effective; however, the metastatic lesion showed regrowth 7 months after these treatments. Because the patient's choroidal oligometastasis was resistant to conservative therapy, left ophthalmectomy was performed. EGFR mutations (L858R and E709K) were detected in the resected choroidal tumor. The patient continued to take gefitinib. However, a neoplastic lesion developed on the optic nerve adjacent to the resected posterior eye segment. The lesion was treated with stereotactic radiation, gefitinib was switched to afatinib 30 mg, and the patient remains alive and disease free for 11 months.

Significance of programmed death-ligand 1 expression in resected lung cancer and its relationship with EGFR mutation.

BACKGROUND: Several studies have reported that the high expression of programmed death-ligand 1 (PD-L1) within tumor cells predicts a poor prognosis. However, the relationship between the PD-L1 expression and lymph node metastasis or driver mutations in lung cancer remains poorly understood. METHODS: A total of 356 consecutive patients who underwent surgical resection for primary lung cancer were included in the study. There were 268 adenocarcinomas including 100 EGFR mutations, 67 squamous cell carcinomas (Sq), and 21 other histologies. The high expression of PD-L1 was defined as a tumor proportion score (TPS) of ≥50. The relationship between the PD-L1 expression and clinicopathological factors and recurrence-free survival (RFS) was analyzed. RESULTS: The PD-L1 expression was high in 75 patients. It was significantly related to smoking history, Sq histology, driver mutation negative, elevated serum carcinoembryonic antigen levels, and lymph node metastasis. Among patients with driver mutations, a high PD-L1 TPS was found in patients with EGFR G719X mutation. A significant difference in RFS was observed in adenocarcinoma patients. A multivariate analysis of adenocarcinoma cases revealed that tumor size and lymph node metastasis were independent prognostic factors for poor RFS, while the PD-L1 expression was not. A logistic regression analysis revealed that the absence of driver mutations, lymph node metastasis, and a history of smoking were significantly associated with the high expression of PD-L1. CONCLUSION: Lymph node metastasis was positively related with the high expression of PD-L1, resulting in poor RFS. A high PD-L1 TPS was observed in patients with the EGFR G719X mutation.

Giant benign intrathoracic schwannoma: a decade-long progression towards fatality.

BACKGROUND: Intrathoracic neurogenic tumors arise from sympathetic nerve trunks and intercostal nerves; more than 90% are benign. Schwannomas are the most common histological variety, but fatalities due to giant schwannomas are rare. CASE PRESENTATION: We report a case of a 65-year-old woman who presented with chest pain and cough. Computed tomography (CT) revealed a large left chest wall mass of 130-mm in size, and the patient was referred to our department. Tumor biopsy was performed under local anesthesia, and a diagnosis of schwannoma was made. Ten years previously, a 30-mm tumor had been noted in the left third intercostal space by a previous doctor, but follow-up had been interrupted owing to depressive disorder. Although we planned to perform intercostal artery embolization followed by chest wall tumor resection, the patient did not consent to surgery due to uncontrolled depression. After four months, she developed respiratory failure caused by compression due to an enlarged tumor and died. Autopsy also revealed a benign schwannoma with no malignant findings. CONCLUSIONS: Although schwannomas are benign tumors, there are some very rare cases in which they can become huge and life-threatening. Therefore, a benign tumor should not be neglected, and if surgery is not possible at the time of diagnosis, a regular follow up is necessary, in order not to miss the right timing for surgery.

Tracheal injury from dog bite in a child.

BACKGROUND: Dog bites associated with the head and neck area in children are a common problem. Most of the lacerations are found in the upper lip and the nose region, and tracheal injury is rare [1]. Tracheal injury requires prompt and accurate diagnosis and treatment to rescue the patient. Especially in children, securing the airway is often more difficult than in adults because of their short neck and narrow trachea. In this report, we experienced a pediatric case of multiple dog bites with tracheal injuries in the neck. CASE PRESENTATION: We report the case of a 3-year-old girl who presented with multiple dog bites. There were multiple wounds on the head, face, neck, and anterior chest, and air leakage was observed from the cervical wound at the time of transfer. It was difficult to perform oral endotracheal intubation, therefore, we extended the neck wound, probed the trachea with finger, and inserted a tracheal tube directly from the cervical wound in the emergency room. Tracheoplasty and another wound cleansing were performed in the operating room. The patient was discharged on the 18th day after surgery, without further complications. CONCLUSION: Tracheal injury from a dog bite is rare. It is important to prompt and accurate diagnosis and treatment. Children should be especially careful because of their short necks and narrow tracheas.

Sentinel node navigation surgery by thoracoscopic fluorescence imaging system and molecular examination in non-small cell lung cancer.

PURPOSE: The application of sentinel node navigation surgery in non-small cell lung cancer (NSCLC) is not popular because of the difficulty of sentinel node identification and the low incidence of complications after systemic lymph node dissection. We report the intraoperative assessment of sentinel node metastasis by thoracoscopic ICG fluorescence imaging system and real-time reverse transcription-polymerase chain reaction (RT-PCR). METHODS: Sixty-one patients who underwent surgery between January 2009 and December 2010 were investigated for sentinel node biopsy. ICG fluorescence imaging was applied by an infrared light CCD system, and sentinel nodes were identified and dissected. Intraoperative real-time quantitative RT-PCR to determine the expression of cytokeratin 19 (CK-19) was performed for evaluation of metastasis and finally histologic examination of hematoxylin and eosin-stained, paraffin-embedded sections. RESULTS: Sixteen (80%) of 20 patients with segmentectomy and 33 (80.5%) of 41 with lobectomy were identified for sentinel lymph nodes. The total identification rate was 80.3% (49 of 61). The false-negative rate was 2.1% (1 of 49). The overall accuracy rate was 78.7% (48 of 61 patients). Disease of four of these patients was upstaged to stage IIA by RT-PCR for CK-19 expression, which was positive for sentinel nodes and micrometastases. CONCLUSIONS: These results demonstrated that thoracoscopic ICG fluorescence imaging-guided surgery and real-time quantitative RT-PCR were useful for sentinel node biopsy and might be a powerful tool for more focused pathologic or molecular evaluation for staging.

Airway Emergencies Due to Anterior Mediastinal T-Lymphoblastic Lymphoma Managed With Planned Extracorporeal Membrane Oxygenation and Endotracheal Stent: A Case Report and Literature Review.

Anterior mediastinal tumors can occasionally cause acute respiratory failure by compressing the trachea and bronchi. In such cases, sedative muscle relaxants during tracheal intubation can cause fatal complete tracheal obstruction. We encountered a 15-year-old male patient with T-lymphoblastic lymphoma (T-LBL) of the anterior mediastinum. For his airway emergency due to the stenosis extended from the lower part of the trachea to the tracheal bifurcation, venovenous (VV) extracorporeal membrane oxygenation (ECMO) was introduced from the femoral vein under local anesthesia. After a short period of tracheal intubation management, an endotracheal stent (ES) was immediately placed in the lower trachea. We performed a needle biopsy, and he was diagnosed with T-LBL. Following the diagnosis, chemotherapy was introduced. The ES was able to secure sufficient tracheal diameter, and ECMO and ventilation were promptly discontinued. In the case of tracheal stenosis from the lower part of the trachea due to anterior mediastinal tumor, depending on the degree of stenosis, VV ECMO can be considered. Moreover, ES can lead to early weaning from VV ECMO and a ventilator.

Aspergillus Nodule in a Patient With Autoimmune Pulmonary Alveolar Proteinosis.

Although autoimmune pulmonary alveolar proteinosis (APAP) is more likely to be associated with infectious diseases, clinical case-based evidence is too limited to confirm this. We describe a case of a man in his late forties diagnosed with APAP nine years prior to the current presentation. A nodule in the right upper lobe gradually increased from 8 to 12 mm over a period of 6 months and was suspicious of malignancy. The pathological analyses revealed Aspergillus nodule without any malignant features. This study aims to report a case of Aspergillus nodule with APAP and discuss the differential diagnosis of solitary lung nodule developed in APAP.

Clinical significance of part-solid lung cancer in the eighth edition TNM staging system.

OBJECTIVES: The ground-glass component of part-solid tumour (PST) was eliminated as a clinical T (cT) descriptor in the eighth edition of the tumour, node and metastasis (TNM) staging system. We aimed to validate the new cT descriptor and investigate the prognostic impact of PST in the new staging system. METHODS: Non-small-cell lung cancer (NSCLC) patients (n = 1061) who underwent lung resection and were available for the assessment of thin-section computed tomography images were retrospectively reviewed. Tumours with a solid component (SC) size-to-whole tumour size (STR) ratio of 0, those with 0 < STR < 1 and those with an STR of 1 were defined as pure ground-glass tumours, PSTs and solid tumours (STs), respectively. RESULTS: Tumours with an SC diameter of >30 mm were less frequently observed among PSTs than among STs (4.83% vs 32.6%, P < 0.001). The postoperative 5-year survival of NSCLC patients with ground-glass tumour, PST and ST was 97.6%, 89.0% and 76.3%, respectively. In the survival analysis of patients with an SC diameter ≤30 mm, significant differences were observed among PST and ST (5-year survival, 90.7% vs 74.6%, P < 0.001). The multivariable analysis showed that age <70 years old, female sex, procedures with a lobectomy or more, SC size, pN0 disease and PST were independent predictors of a better survival among all PST and ST patients. CONCLUSIONS: Among patients with cT1 tumours, those with PST showed a significantly better survival than did those with ST. Small-sized PST tumours may not be suitable for the new cT descriptor.

Prognostic significance of HE4 expression in pulmonary adenocarcinoma.

We investigated the possibility of human epididymis 4(HE4) to predict survival for patients with pulmonary adenocarcinoma. One hundred and thirty-seven patients with pulmonary adenocarcinoma underwent surgery in our institute from 2000 to 2008. We used immunohistochemical analysis to determine the expression of HE4 and compared with the clinicopathological factors and survival. Serum levels of HE4 in lung adenocarcinoma were investigated by enzyme immunometric assay. Fifty-seven of 137 cases (41.6%) were HE4 positive. It was found that there was no correlation between HE4 expression by immunohistochemistry and clinicopathological factors, however, adenocarcinoma subtype was significantly associated with HE4 expression. Sera in lung adenocarcinoma were significantly higher than in healthy control. Five-year disease-free survival in the HE4-positive group (44.6%) was significantly different from that in the negative group (82.3%, p = 0.001) by immunohistochemistry. The five-year overall survival rate was 60.1% in the HE4-positive group, as compared with 90.8% in the HE4-negative group (p = 0.001). In multivariate Cox regression analysis, positive HE4 protein expression was a worse prognosis factor of disease-free and overall survival (HR = 3.7, 95%CI = [1.7-8.4], p = 0.001; HR = 5.5, 95%CI = [1.8-17.2], p = 0.003, respectively), in addition to nodal status as a powerful value. When HE4 expression in adenocarcinoma cases except the BAC were analyzed, nodal status and HE4 expression were independent prognostic factors in disease-free and overall survivals. These data showed that HE4 expression is associated with a worse prognosis and is a possible prognostic factor of lung adenocarcinoma.

Clinical impact of segmentectomy compared with lobectomy under complete video-assisted thoracic surgery in the treatment of stage I non-small cell lung cancer.

BACKGROUND: Segmentectomy for small or early stage non-small cell lung cancer (NSCLC) has been controversial. Further, video-assisted thoracic surgery (VATS) for lung cancer was accepted during the past decade. We here compared the outcome between VATS segmentectomy and VATS lobectomy for stage I NSCLC. METHODS: In the retrospective study, 109 consecutive patients in stage I underwent surgery at Oita University Hospital (Oita, Japan) between September 2003 and October 2008. VATS segmentectomy was performed in 38 patients and VATS lobectomy with systemic lymphadenectomy was performed in 71 patients. After clinicopathologic factors were compared in both groups, local recurrence rates and survivals were compared. RESULTS: Five of 38 VATS segmentectomy and eight of 71 VATS lobectomy patients relapsed during the follow-up period (median 27.5 mo). In the relapsed patients after VATS segmentectomy, three (7.9%) were local recurrences and two (5.3%) were distant metastases. On the other hand, four (5.6%) were local recurrence and four (5.6%) were distant metastases in the VATS lobectomy group. There was no significant difference between the two groups. Furthermore, there was no difference in recurrence-free and overall survival between segmentectomy and lobectomy. CONCLUSIONS: Although the sample size is small, VATS segmentectomy is one of the appropriate procedures for stage I NSCLC.

Resection and postoperative radiation therapy for desmoid fibromatosis of the chest wall in a young woman.

BACKGROUND: Surgery is an effective treatment for desmoid fibromatosis, but it may be difficult, depending on the location or local spread of the tumor, and the decision to perform surgery must be made carefully. We herein report a case of desmoid fibromatosis of the chest wall in a young woman suspected of having invasion to the 1st, 2nd and 3rd ribs. CASE PRESENTATION: A 35-year-old woman had been aware of dry cough and right chest pain, so she was referred to our hospital. Chest computed tomography showed a localized pleural tumor mainly at the first rib. Magnetic resonance imaging revealed a 75 × 65 × 27-mm tumor with a smooth surface, with partial contact from the first rib to third rib and partial extension to the 1st intercostal space. The tumor showed growth in the two months after the first visit, so resection was performed. The tumor was completely resected, and adjuvant radiation therapy (50 Gy) was performed for the small margin. The pathological diagnosis was desmoid fibromatosis. The postoperative course has been uneventful, without recurrence at 14 months after surgery. CONCLUSIONS: In chest wall tumors located ventral of the pulmonary apex, we suggest that a combination of the Grunenwald method and Masaoka anterior approach may be a useful option. In cases where margin is not enough, adjuvant radiation therapy should be considered.

Thymoma-associated myasthenia gravis coexisting with myotonic dystrophy: a case report.

BACKGROUND: Myotonic dystrophy (dystrophia myotonica [DM]) is an autosomal-dominant inheritance, and myasthenia gravis (MG) is an autoimmune disease characterized by weakness of skeletal muscles. Cases of both DM and MG are extremely rare and distinguishing DM and MG symptoms is challenging. CASE PRESENTATION: We herein report a 49-year-old woman presenting with subacute dyspnea and muscle weakness. She had previously been diagnosed with DM 24 years earlier. Computed tomography (CT) revealed an anterior mediastinal 32-mm solid mass that was suspected of being thymoma. The clinical features and neurological examination findings confirmed the diagnosis of thymoma-associated MG coexisting with DM. Intensive treatment for MG, including surgery, resulted in an improvement in some of her neurological symptoms. CONCLUSIONS: The symptoms of DM usually progress slowly, so the sudden exacerbation of symptoms indicates the involvement of other factors. It is important to be aware of these associations, as an early diagnosis with proper treatment will result in a better outcome.

Evaluating the Platelet Distribution Width-to-Plateletcrit Ratio as a Prognostic Marker for Patients With Breast Cancer.

AIM: This study aimed to evaluate plateletcrit (PCT) and platelet distribution width-to-PCT ratio (PDW/PCT) as potential prognostic biomarkers in patients with breast cancer. PATIENTS AND METHODS: Information of 337 patients was retrospectively reviewed. The Cox regression proportional hazards model was used to evaluate the prognostic value of PCT and PDW/PCT compared to the platelet distribution width-to-platelet count ratio (PDW/P) and red cell distribution width-to-platelet count ratio (RDW/P). RESULTS: Large tumor size (p<0.01), lymph node involvement, and increased PDW/P, RDW/P, and PDW/PCT (p<0.05) were significantly associated with inferior disease-free survival (DFS) according to the univariate analysis. The multivariate analysis showed that large tumor size (p<0.01) and increased PDW/PCT (p<0.05) were significant prognostic factors for poor DFS. CONCLUSION: To our knowledge, this is the first report to show that PDW/PCT is a significant prognostic factor for patients with breast cancer. Therefore, it might be an attractive biomarker providing additional prognostic information for these patients.

Ciliated muconodular papillary tumor of the lung: a case report and literature review.

Ciliated muconodular papillary tumor (CMPT) of the lung is characterized as a peripheral low-grade malignant tumor with ciliated columnar cells and goblet cells with basaloid cell proliferation. Herein, we report on a case of CMPT with a radiologically abnormal shadow which was reminiscent of adenocarcinoma. The patient underwent right S6 + S8a segmentectomy because an intraoperative biopsy suggested CMPT, the malignancy of which was difficult to distinguish; however, the tumor was small and located in the peripheral lung. Many details of this tumor remain unclear, as CMPT is a rare tumor with few reports. CMPT has therefore not yet been classified by the WHO. In this report, we will consider the characteristics of CMPT and treatment based on our case and previous case reports.

Elevated red cell distribution width to platelet count ratio predicts poor prognosis in patients with breast cancer.

Red cell distribution width (RDW) to platelet ratio (RPR) is a prognosticator in acute pancreatitis and myocardial infarction; however, the prognostic values of RDW and RPR in breast cancer have not been studied. This retrospective analysis of 299 breast cancer patients investigated the association between RDW and RPR and clinicopathological characteristics and prognosis, compared to platelet distribution width to platelet count ratio (PDW/P) which is a known independent prognostic factor in patients with breast cancer. We found a significant correlation between RPR, and age and HER2 status. An elevated RPR significantly correlated with age and HER2 status. After a median follow-up duration of 48 months, tumour size, nuclear grade, PDW/P, and RPR were recgnized to be significantly associated with lower disease-free survival rates (tumour size: p < 0.01; nuclear grade, PDW/P, and RPR: p < 0.05) in univariate analysis. Tumour size and RPR were significant prognostic factors for lower disease-free survival rates, with hazard ratios of 4.31 (95% confidence interval: 1.76-10.53) (p < 0.01)] and 2.79 [95% confidence interval: 1.01-87.69) (p < 0.05)], respectively, in a multivariate analysis using the Cox proportional hazards model. This is the first study showing that an elevated RPR could independently predict poor prognosis in patients with breast carcinoma. Thus, RPR could be a novel biomarker for prognostic estimation.

Erlotinib and bevacizumab combination therapy for afatinib-refractory leptomeningeal carcinomatosis from EGFR-mutated lung cancer.

Acquired resistance to epidermal growth factor receptor tyrosine kinase inhibitors remains the main hurdle in treating EGFR-mutated lung cancer. Besides, when leptomeningeal carcinomatosis occurs during treatment, it often leads to treatment failure. We herein report a case of lung adenocarcinoma involving a patient with an EGFR exon 19 deletion mutation who developed leptomeningeal carcinomatosis after afatinib treatment for post-operative recurrence. He received right lower lobectomy, followed by four cycles of cisplatin and pemetrexed treatment. Follow-up CT/MRI revealed multiple pulmonary metastases and brain metastases at 7 months after surgery, and afatinib (40 mg/day) was administered after stereotactic radiotherapy for brain metastasis. At 28 months after surgery, follow-up MRI revealed asymptomatic leptomeningeal carcinomatosis, which was cytologically proven from the cerebrospinal fluid. Because EGFR T790M was not detected in plasma cell-free DNA or cerebrospinal fluid, erlotinib and bevacizumab combination treatment was administered. He remained asymptomatic and was radiographically clear of LM at 2 months after treatment. In comparison to other EGFR-TKIs, erlotinib shows penetrance into the cerebrospinal fluid. Furthermore, the addition of bevacizumab might enhance the treatment effect, because it is known to relieve brain edema from metastatic brain tumors by normalizing immature vascularity and improving drug penetrance into the cerebrospinal fluid by reducing interstitial fluid pressure.

Phosphorylation status of epidermal growth factor receptor is closely associated with responsiveness to gefitinib in pulmonary adenocarcinoma.

Twenty-one cases of primary lung carcinoma were analyzed for correlations between the presence of somatic mutations of the epidermal growth factor receptor (EGFR) gene and the phosphorylation status of EGFR, which was analyzed by immunohistochemistry with antibodies recognizing the phosphorylated form of EGFR. Somatic mutations were detected in 11 (52.4%) of the 21 cases. Immunohistochemistry with an antibody recognizing EGFR phosphorylated at tyrosine (pEGFR-tyr) 992 and an antibody recognizing EGFR phosphorylated at tyrosine 1173 (pEGFR-tyr1173) revealed that 12 (57.1%) and 21 (100%) of the 21 cases were positive, respectively. Interestingly, the mutation status of the EGFR gene was strongly correlated with immunoreactivity for pEGFR-tyr992 (P = .0019). pEGFR-tyr992 immunoreactivity was significantly correlated with clinical responsiveness to gefitinib (P = .0011). These findings suggest that immunohistochemical evaluation with anti-pEGFR-tyr992 antibody is useful for prediction of responsiveness to gefitinib.