Screening for EGFR and KRAS mutations in non-small cell lung carcinomas using DNA extraction by hydrothermal pressure coupled with PCR-based direct sequencing

EGFR and KRAS mutations correlate with response to tyrosine kinase inhibitors in patients with non-small cell lung carcinoma (NSCLC). We reported a hydrothermal pressure method of simultaneous deparaffinization and lysis of formalin-fixed paraffin embedded (FFPE) tissue followed by conventional chaotropic salt column purification to obtain high quality DNA for mutation analysis using PCR-base direct sequencing. This study assessed the feasibility of using this method to screen for exons 18-21 of EGFR and exon 2 of KRAS gene mutations in surgical resection and core needle biopsy specimens from 251 NSCLC patients. EGFR mutations were identified in 140 (55.8%) NSCLC patients (118 in adenocarcinoma, 11 in squamous cell carcinoma, 7 in adenocarcinoma and 4 in NSCLC-not otherwise specified), including four novel substitutions (L718M, A743V, L815P, V819E). EGFR mutations were frequently present in female patients (72 of 113, 63.7%) and NSCLC with adenocarcinoma component (125/204, 61.3%) with statistical significance. Twenty-one patients had multiple mutations at different exons of EGFR, in which seventeen patients had deletions in exon 19. KRAS mutations were found in 18 (7.2%) patients (15 in adenocarcinoma, 2 in squamous cell carcinoma and one in NSCLC-not otherwise specified), including an uncommon substitution G13C. Deparaffinization and lysis by hydrothermal pressure, coupled with purification and PCR-based sequencing, provides a robust screening approach for EGFR and KRAS mutation analysis of FFPE tissues from either surgical resection or core needle biopsy in clinical personalized management of lung cancer.     

Large cell carcinoma of the lung: clinically oriented classification integrating immunohistochemistry and molecular biology

This study aimed at challenging pulmonary large cell carcinoma (LLC) as tumor entity and defining different subgroups according to immunohistochemical and molecular features. Expression of markers specific for glandular (TTF-1, napsin A, cytokeratin 7), squamous cell (p40, p63, cytokeratins 5/6, desmocollin-3), and neuroendocrine (chromogranin, synaptophysin, CD56) differentiation was studied in 121 LCC across their entire histological spectrum also using direct sequencing for epidermal growth factor receptor (EGFR) and v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog (KRAS) mutations and FISH analysis for ALK gene translocation. Survival was not investigated. All 47 large cell neuroendocrine carcinomas demonstrated a true neuroendocrine cell lineage, whereas all 24 basaloid and both 2 lymphoepithelioma-like carcinomas showed squamous cell markers. Eighteen out of 22 clear cell carcinomas had glandular differentiation, with KRAS mutations being present in 39 % of cases, whereas squamous cell differentiation was present in four cases. Eighteen out of 20 large cell carcinomas, not otherwise specified, had glandular differentiation upon immunohistochemistry, with an exon 21 L858R EGFR mutation in one (5 %) tumor, an exon 2 KRAS mutation in eight (40 %) tumors, and an ALK translocation in one (5 %) tumor, whereas two tumors positive for CK7 and CK5/6 and negative for all other markers were considered adenocarcinoma. All six LCC of rhabdoid type expressed TTF-1 and/or CK7, three of which also harbored KRAS mutations. When positive and negative immunohistochemical staining for these markers was combined, three subsets of LCC emerged exhibiting glandular, squamous, and neuroendocrine differentiation. Molecular alterations were restricted to tumors classified as adenocarcinoma. Stratifying LCC into specific categories using immunohistochemistry and molecular analysis may significantly impact on the choice of therapy.     

Mutation status of somatic EGFR and KRAS genes in Chinese patients with prostate cancer (PCa)

Activating mutations of the epidermal growth factor receptor (EGFR) confers sensitivity to tyrosine kinase inhibitors (TKIs). In colorectal cancer and in lung adenocarcinomas, clinical trials have shown a lack of response to anti-EGFR therapy when KRAS gene mutations are present. In this study, the mutation status of specified exons of the EGFR and KRAS genes was profiled in patients with prostate cancer (PCa). Direct Sanger sequencing was used to screen for mutations in exons 19–21 of EGFR and in exon 2 of KRAS in 88 Chinese patients diagnosed with prostate adenocarcinomas. Mutations were detected in 11 patients. In nine cases (10 %), activating mutations in the region of EGFR encoding the tyrosine kinase (TK) domain were present. Deletions in exon 19 and the L858R substitution in exon 21 were “hotspot” mutations, together accounting for five (55 %) of nine cases. Many synonymous substitutions were also detected. KRAS mutations were found in two cases (2.3 % of 88). There were no cases with mutations in both EGFR and KRAS, suggesting that mutations in the two genes might be mutually exclusive. Although prognostic relevance of EGFR expression by immunohistochemistry (IHC) was observed in PCa patients in previous studies, we found no statistically significant association between EGFR or KRAS mutations and clinicopathological features (including age, smoking status, preoperative prostate-specific antigen, Gleason scores, and tumor stage). We contend that accurate profiling of the mutation status of EGFR and KRAS could improve prognostic stratification, and we suggest a potential anti-EGFR therapy for patients with PCa with EGFR mutations.     

Epidermal growth factor receptor and KRAS mutations in Brazilian lung cancer patients

OBJECTIVE:

Epidermal growth factor receptor is involved in the pathogenesis of non-small cell lung cancer and has recently emerged as an important target for molecular therapeutics. The KRAS oncogene also plays an important role in the development of lung cancer. The aim of this study was to evaluate the frequency of epidermal growth factor receptor and KRAS mutations in a population of Brazilian patients with non-small cell lung cancer.

METHODS:

A total of 207 specimens from Brazilian patients with non-small cell lung cancer were analyzed for activating epidermal growth factor receptor and KRAS somatic mutations, and their associations with clinicopathological characteristics (including age, gender, ethnicity, smoking habits, and histological subtype) were examined.

RESULTS:

We identified 63 cases (30.4%) with epidermal growth factor receptor mutations and 30 cases (14.6%) with KRAS mutations. The most frequent epidermal growth factor receptor mutation we detected was a deletion in exon 19 (60.3%, 38 patients), followed by an L858R amino acid substitution in exon 21 (27%, 17 patients). The most common types of KRAS mutations were found in codon 12. There were no significant differences in epidermal growth factor receptor or KRAS mutations by gender or primary versus metastatic lung cancer. There was a higher prevalence of KRAS mutations in the non-Asian patients. Epidermal growth factor receptor mutations were more prevalent in adenocarcinomas than in non-adenocarcinoma histological types. Being a non-smoker was significantly associated with the prevalence of epidermal growth factor receptor mutations, but the prevalence of KRAS mutations was significantly associated with smoking.

CONCLUSIONS:

This study is the first to examine the prevalence of epidermal growth factor receptor and KRAS mutations in a Brazilian population sample with non-small cell lung cancer.     

Detecting EGFR alterations in clinical specimens—pitfalls and necessities

We investigated the epidermal growth factor receptor (EGFR) status in early stage lung cancer in Southern Sweden, a population for which there are no previous reports on the EGFR mutation frequency. Three hundred fifty small cell lung cancers, adenocarcinomas (AC), squamous cell carcinomas (SqCC), and large cell carcinomas were analyzed using a combination of techniques for the analysis of protein expression, gene copy numbers, and mutations. Immunohistochemical (IHC) staining with antibodies for the EGFR mutations L858R and del E746-A750 revealed intratumoral heterogeneity and several discrepant cases when compared to mutation-specific polymerase chain reaction (PCR)-based analysis. The frequencies of these two mutations, when considering IHC staining with mutation-specific antibodies in a cohort of 298 cases and subsequent confirmation by PCR, were 10 % in AC and <2 % in SqCC. Furthermore, screening by sequencing of EGFR in a cohort of 52 lung AC and squamous carcinomas demonstrated a more diverse mutation spectrum, not covered by the mutation-specific antibodies. High expression of total EGFR protein was correlated to high gene copy numbers but did not reflect the mutational status of the tumors. We believe that the mutation spectra in a Southern Swedish population is too diverse to be covered by the mutation-specific antibodies, and we also raise some other issues regarding the use of the mutation-specific antibodies, for example concerning heterogeneous expression of the mutated protein, optimal antibody dilution, and discrepancies between staining results and PCR.     

New monoallelic combination of KRAS gene mutations in codons 12 and 13 in the lung adenocarcinoma

PurposeIn a retrospective analysis of the prevalence of KRAS mutations in patients with advanced non-small cell lung cancer (NSCLC), we detected a unique and not earlier described case of a double combination of mutations at codons 12 and 13 of the KRAS gene in a patient with lung adenocarcinoma.Material/MethodsTo determine the molecular characteristics of the infrequent mutation and the mutational status of the KRAS gene in metastatic brain tumors in the same patient, we performed morphological and molecular tests.ResultsMolecular analysis of the nature of the double mutation showed that the unique combination of variants is a monoallelic mutation. This type of changes has not yet been registered in the Catalogue of Somatic Mutations in Cancer database. Molecular assessment of the KRAS mutation status in the brain metastatic site in the same patient, showed no mutations in codons 12 and 13. Moreover, we did not find mutation at exon 19 and 21 of EGFR gene, both in primary tumor as well as in secondary metastatic foci in the brain.ConclusionsThe presented case shows an example of KRAS gene molecular mosaicism and heterogeneity of lung adenocarcinoma primary and metastatic tumors. Molecular heterogeneity of lung adenocarcinoma tumors can significantly affect eligibility of patients for targeted therapies.     

Lung cancer presenting with central nervous system metastasis: Clinicopathological and molecular analysis of 171 cases

A subset of lung carcinoma presents initially with brain metastasis. Precise subtyping is mandatory for optimized treatment of these advanced aggressive carcinomas. We herein analyzed surgical biopsies from 171 Patients (99 males and 72 females aged 48–96; mean, 72), who presented with brain metastasis of lung cancer. In addition to conventional subtyping, we applied an extended immunohistochemistry (IHC) panel and performed several molecular tests looking for potential therapeutic targets other than EGFR mutations. Non-small cell carcinoma (NSCLC) comprised 157 (91.8 %) of cases: 109 (63.7 %) adenocarcinomas, 27 (15.8 %) squamous cell (SCC), 18 (10.5 %) large cell undifferentiated, 1 (0.6 %) adenosquamous and 2 (1.2 %) unclassified carcinomas. Of the adenocarcinomas, 81.7 % were TTF1+. Notably, 45 % of those TTF1-negative cases expressed HepPar1. SMARCA4 and SMARCA2 loss was observed in 13/171 (7.6 %) and 32/163 (19.6 %) cases, respectively; mainly TTF1- (40.0 %) and HepPar1+ (38.1 %) adenocarcinomas were affected by SMARCA2/4 loss. Loss of at least one mismatch repair (MMR) protein was observed in 3/156 (1.9 %) cases (2 adenocarcinomas and 1 large cell neuroendocrine carcinoma/LCNEC). Limited available data on mutation testing showed a frequency of EGFR mutations of 4.3% and of KRAS mutations of 57%. HER2 expression (2+/3+) was found in 45/166 (27.1 %) of cases with amplification verified by CISH in 18/38 (47.4 % of immunopositive cases and 10.5 % of the whole cohort); all but one were adenocarcinomas. Other genetic abnormalities detected included EML4::ALK rearrangements in 3 (1.8 %; 2 TTF1+ adenocarcinomas and 1 LCNEC) and RET rearrangements in one SCNEC. Variable subsets of tumors revealed amplifications of several potentially therapeutically targetable genes including MYC (30.0 %), MET (10.1 %), HER2 (10 %), FGFR1 (9.6 %), FGFR3 (4.6 %), and FGFR2 (3.4 %). This study highlights a highly heterogeneous molecular background in lung cancer presenting with CNS metastases. These findings highlight the need for individualized tumor testing strategies looking for potential therapeutic targets for this aggressive disease.     

Intratumoral heterogeneity of KRAS mutation is rare in non-small-cell lung cancer

Background

Several lines of evidence indicate that mutational activation of KRAS is an early event in the carcinogenesis of non-small cell lung cancer (NSCLC). Nonetheless, previous studies report high frequencies of divergent KRAS mutational status between primary NSCLC and corresponding metastases. This suggests heterogeneity of the primary tumor in respect to its KRAS status. We therefore aimed to examine the frequency and the extent of such intratumoral heterogeneity.

Methods

40 NSCLC were examined for intratumoral heterogeneity of KRAS mutation (20 adenocarcinomas, 10 squamous cell carcinomas and 10 large cell carcinomas). Three to eight different tumor areas were analyzed for KRAS mutation and up to four corresponding lymph node metastases were included for analysis in nineteen cases. A combination of different methods for screening of heterogeneity and its validation were used including direct sequencing, laser-capture microdissection for tumor cell enrichment and the very sensitive ARMS/S method.

Results

Mutations of KRAS were found in 13/30 adenocarcinomas and large cell carcinomas. No mutations were detected in 10 squamous cell carcinomas. Four cases showed heterogeneous KRAS results by direct sequencing. More sensitive methods for KRAS mutation analysis revealed false negative results due to admixture of non-neoplastic cells in all of these samples. Intratumoral heterogeneity of KRAS mutational status was therefore confirmed in none of the analyzed cases. In addition, identical KRAS mutations were present in the primary tumor and the corresponding lymph node metastases in 19 cases examined.

Conclusions

Intratumoral heterogeneity of KRAS mutational status is rare in NSCLC but highly sensitive tools are required to reliably identify these mutations. This finding is in line with the hypothesis that oncogenic activation of KRAS is an early event and a bona fide “driver mutation” in NSCLC. Furthermore, future therapies targeting KRAS will not be limited by intratumoral heterogeneity.     

Detection of EML4-ALK fusion genes in non-small cell lung cancer patients with clinical features associated with EGFR mutations

EML4‐ALK fusion genes have been recognized as novel “driver mutations” in a small subset of non‐small cell lung cancers (NSCLC). The frequency of EML4‐ALK fusions in NSCLC patients who have clinical characteristics related to EGFR mutation remains unknown. We screened 102 Chinese patients with NSCLC based on one or more of the following characteristics: female, no or light smoking history, and adenocarcinoma histology. EML4‐ALK fusion genes were identified by RT‐PCR, whereas EGFR (Exons 18–21) and KRAS (Exons 1 and 2) mutations were detected by DNA sequencing. Eight specimens (8%) were positive for EML4‐ALK fusions, with seven being Variant 1 and one Variant 2. There were 44 (43%) and 17 (16%) patients harboring EGFR and KRAS mutations, respectively. Thirty‐one (31%) cases were wild type for EML4‐ALK, EGFR, and KRAS mutations. Of the eight patients with EML4‐ALK, none had an EGFR mutation, whereas a KRAS mutation was detected in one patient. Histologically, five of the EML4‐ALK positive tumors were adenocarcinoma and two were mixed adenosquamous carcinoma; only one was a squamous carcinoma. Our data support the conclusion that the EML4‐ALK fusion gene defines a new molecular subset of NSCLC with distinct pathologic features. © 2012 Wiley Peiodicals, Inc.     

Can EGFR mutation status be reliably determined in pre‐operative needle biopsies from adenocarcinomas of the lung?

The identification of EGFR mutations in non‐small‐cell lung cancer is important for selecting patients, who may benefit from treatment with EGFR tyrosine kinase inhibitors. The analysis is usually performed on cytological aspirates and/or histological needle biopsies, representing a small fraction of the tumour volume. The aim of the present investigation was to evaluate the diagnostic performance of this molecular test. We retrospectively included 201 patients with primary adenocarcinoma of the lung. EGFR mutation status (exon 19 deletions and exon 21 L858R point mutation) was evaluated on both pre‐operative biopsies (131 histological and 70 cytological) and on the surgical specimens, using PCR. Samples with low tumour cell fraction were assigned to laser micro‐dissection (LMD). We found nine (4.5%) patients with EGFR mutation in the lung tumour resections, but failed to identify mutation in one of the corresponding pre‐operative, cytological specimens. Several (18.4%) analyses of the pre‐operative biopsies were inconclusive, especially in case of biopsies undergoing LMD and regarding exon 21 analysis. Discrepancy of mutation status in one patient may reflect intra‐tumoural heterogeneity or technical issues. Moreover, several inconclusive results in the diagnostic biopsies reveal that attention must be paid on the suitability of pre‐operative biopsies for EGFR mutation analysis.     

Analysis of the proliferative activity in lung adenocarcinomas with specific driver mutations

In the last decade it became evident that many lung adenocarcinomas (ADC) harbor key genetic alterations such as KRAS, EGFR or BRAF mutations as well as rearrangements of ROS1 or ALK that drive these tumors. In the present study we investigated whether different driver mutations of ADC result in different proliferation rates, which might have clinical impact, including resistance to therapy, recurrence and prognosis.We analyzed the proliferation index (PI) on full slides of surgically resected ADC (n?=?230) with known genetic aberrations by means of immunohistochemistry and subsequent digital image analysis and correlated the results with clinicopathological variables including overall (OS) and disease free survival (DFS).We did not observe significant differences in OS or DFS regarding the KRAS or EGFR mutational status (P?=?0.56). However, KRAS mutated ADC showed an increased PI compared to EGFR mutated ADC, and ADC with ALK translocations (P?<?0.01). Subgroup analysis of EGFR mutated ADC showed a higher PI for tumors harboring a mutation in exon 18 and 20, compared to tumors with a mutation in exon 19 or 21. A PI of 11.5% was the best possible prognostic stratificator for OS (P?=?0.01 in KRAS mutated and P?<?0.01 in EGFR mutated ADC).In conclusion, the PI differs significantly among ADC with distinct driver mutations. This might explain the varying indications for a prognostic relevance of the PI observed in prior studies. Our study provides a basis for the establishment of a reliable and clinically meaningful PI threshold.     

EGFR mutation L747P led to gefitinib resistance and accelerated liver metastases in a Chinese patient with lung adenocarcinoma

Background: Mutations in the epidermal growth factor receptor gene (EGFR) are found in around half of Asian patients with non-small cell lung cancer (NSCLC). For this reason, EGFR tyrosine kinase inhibitors (TKI) are often prescribed depending on the EGFR status. Two common EGFR mutations, a deletion in exon 19 and L858R in exon 21, demonstrate a positive response to gefitinib, the first approved EGFR TKI. However, T790M and an insertion in EGFR exon 21 are resistant to EGFR TKI treatment. The relationships between the EGFR mutation type and response to the target drug have not been fully investigated. Case presentation: We describe a 66-year-old Chinese male diagnosed with stage IV lung adenocarcinoma based on evidence from a computed tomography (CT) scan and histological features of a biopsy taken during fiberoptic bronchoscopy surgery. Molecular analysis of EGFR exons 19 and 21 revealed the presence of only one mutation in exon 19: L747P (2239-2240 TT>CC). The patient requested gefitinib treatment for 2 weeks but his response was poor. A CT scan revealed that the number and relative volume of the liver metastases had increased after treatment. Conclusion: L747P (2239-2240 TT>CC) in exon 19 is a rare EGFR mutation that appears to lead to gefitinib resistance and might accelerate liver metastases.     

Optimized algorithm for Sanger sequencing-based <Emphasis Type="Italic">EGFR</Emphasis> mutation analyses in NSCLC biopsies

Pulmonary adenocarcinoma patients harboring EGFR mutations can benefit from tyrosine kinase inhibitor therapy. Reliable molecular analyses and precise pathological reporting of the EGFR mutational status are factors essential for patient treatment and outcome. More than 70 % of all EGFR mutation analyses are performed on non-small cell lung cancer (NSCLC) biopsies. However, biopsies may not be sufficient for mutation analysis due to low tumor content and admixture with non-neoplastic cells. To define the minimal concentration of tumor cells required for reliable EGFR mutational diagnostics by Sanger sequencing and to develop an algorithm for routine diagnostics on biopsy material, we determined total numbers of tumor and non-tumor cells, calculated the tumor cell concentration and serially diluted DNA from EGFR-mutated NSCLC by adding DNA of non-tumor cells from the same section. A counted tumor cell concentration of 30 %, which refers to a histologically estimated concentration of 40 %, is necessary for reliable detection of all mutations. Based on these data, we developed an algorithm for evidence-based EGFR mutation analysis by Sanger sequencing in biopsy specimens, which was subsequently applied to 461 diagnostic cases. Optimized diagnostic testing results in 80 % reliable EGFR mutation analyses of biopsy specimens, while in 20 % of cases re-biopsies had to be recommended.     

Detection of EGFR mutation in supernatant,cell pellets of pleural effusion and tumor tissues from non-small cell lung cancer patients by high resolution melting analysis and sequencing

To determine epidermal growth factor receptor (EGFR) mutation in advanced non-small cell lung cancer (NSCLC) patients and compare the detection efficiency between different sample resources, both high resolution melting (HRM) analysis and direct sequencing method were used to analyze 36 pleural effusion samples and 22 matched biopsy tumor tissues collected from NSCLC patients. For each pleural effusion sample, the supernatant and the cell pellets were examined separately. Among all the 36 cases of pleural effusion samples, 18 mutations of EGFR were found in cell-free supernatant while 13 mutations were found in the cell pellets as detected by HRM analysis. In the 22 matched samples, 13 cases of EGFR mutations were identified in paraffin-embedded biopsy tissue samples, 12 cases in the cell-free supernatant and 9 cases in the cell pellets of pleural effusion. EGFR mutations in 15 cases out of the total 36 pleural effusion samples detected by direct sequencing were also identified by HRM analysis, giving 100% efficiency for HRM method. The results established the important role of HRM as a reliable and efficient method to determine EGFR mutation status and indicated the feasibility of using pleural effusion in replacement of biopsy tissues in particular clinical cases. Furthermore, the cell-free supernatant of pleural effusion might be a better resource for mutation detection than cell pellets.     

Sinonasal papillomas: A single centre experience on 137 cases with emphasis on malignant transformation and EGFR/KRAS status in “carcinoma ex papilloma”

Among the three major histological subtypes of sinonasal papillomas, inverted (ISP) and oncocytic (OSP) sinonasal papillomas tend to undergo malignant transformation to carcinoma. However, criteria determining risk of recurrence and malignant progression have not been established. Recently, EGFR and KRAS mutations were detected to be characteristic for ISP and OSP, respectively. In this study, we analyzed 137 sinonasal papilloma cases (132 ISP and 5 OSP) for clinicopathological characteristics, frequency of recurrences/malignant transformation, and histological types and genetic features of carcinoma ex Schneiderian papilloma. OSP presented at a higher age than ISP (median, 75 vs. 57 years) and affected predominantly females. Overall frequency of recurrences and malignant transformation was 23.1% and 9.5%, respectively. Rates of recurrence (33.3% vs. 22.0%) and malignant transformation (33.3% vs. 8.8%) were higher in OSP compared to ISP, respectively. Carcinomas (n = 10) occurred mostly synchronously, more frequently in females and mainly associated with ISP (n = 9). Squamous cell carcinoma (SCC) was the most frequently associated malignancy. Concordant EGFR (in ISP/associated carcinoma) and KRAS (in the OSP/associated carcinoma) mutations were detected in all successfully analyzed matching papilloma/carcinoma pairs, confirming their shared clonal origin. Results of this large study are in line with recent studies showing frequent EGFR and KRAS mutations in sinonasal carcinoma ex Schneiderian papilloma. As the papilloma component might on occasion be missed on biopsy of synchronous carcinoma ex papilloma, EGFR and KRAS mutation testing represents a promising molecular surrogate for sinonasal “carcinoma ex papilloma”, at the same time offering an opportunity for targeting mutant EGFR in this rare cancer type.     

Non-small cell lung carcinomas with CTNNB1 (beta-catenin) mutations: A clinicopathological study of 26 cases

Beta-catenin, encoded by the CTNNB1 gene, plays an important role in cell proliferation. Mutations of CTNNB1 are oncogenic in several tumor types and are often associated with a nuclear abnormal expression. However, such mutations have only rarely been reported in non-small cell lung carcinomas and their clinical signification is not well described.Our study was conducted on 26 CTNNB1-mutated non-small cell lung carcinomas. Tumors were routinely tested by next generation sequencing for mutations in exon 3 of CTNNB1 gene. Twenty three cases were from a series of 925 tumors (2.48%). The hospital files and pathological data, from surgical samples (n = 16), small biopsies (n = 5) and trans-bronchial fine needle aspirations (n = 5), were reviewed. Immunohistochemistry was performed with an anti-beta-catenin antibody.There were 10 female and 16 male patients aged 52 to 83. Eleven of 25 patients were no-smoking or light smokers. Three cases were diagnosed while under treatment with EGFR tyrosine kinase inhibitor. There were 25 adenocarcinomas and 1 squamous cell carcinoma. Most adenocarcinomas had a papillary component and were TTF1-positive. One case was a well-differentiated fetal adenocarcinoma. Eleven cases (42%) with CTNNB1 mutations showed associated EGFR mutations. The frequency of CTNNB1 mutations was higher among EGFR mutated carcinomas. Immunohistochemistry showed heterogeneous nuclear or cytoplasmic abnormal expression.Our study shows that CTNNB1 mutations mostly occur in TTF1-positive adenocarcinomas with a papillary pattern. These mutations are often associated with EGFR mutations and possibly interfer in the mechanism of resistance to tyrosine kinase inhibitors. Our experience suggests that immuno-histochemistry cannot be used for screening.     

肺癌中P63与P53、E-cadherin、Ki-67表达的比较

目的　比较 p6 3及 p5 3、E cadherin(E cad)、Ki 6 7在肺癌中的表达 ,以了解在不同组织类型肺癌发生发展过程中 ,p6 3与抑癌基因 (p5 3)突变、上皮分化标志基因 (E cad)失活及细胞增殖标志基因 (Ki 6 7)激活有无相关性。方法　采用免疫组化S P法分别检测 6 1例原发性肺癌中 p6 3、p5 3、E cad和Ki 6 7的表达情况。 结果　p6 3在肺鳞癌中阳性率为 10 0 0 % ,而在其他组织类型肺癌中 p6 3基本不表达 ,差异有显著性 (P <0 0 5 ) ;在不同分化程度的肺鳞癌中 p6 3、p5 3的表达差异有显著性 (P<0 0 5 ) ,E cad、Ki 6 7的表达差异无显著性 (P >0 0 5 ) ;E cad的表达在小细胞肺癌与肺鳞癌和肺腺癌之间差异有显著性 (P <0 0 5 ) ;Ki 6 7的表达在各种组织类型肺癌之间差异有显著性 (P <0 0 5 ) ;在不同分化程度鳞癌中 p6 3与E cad的表达呈负相关(P <0 0 5 )。结论　p6 3可作为鳞状上皮源性肿瘤标记物 ,是判断鳞状细胞癌的增殖和分化有意义的指标 ,并可作为鉴别分化差的鳞癌和腺癌、小细胞癌的指标。