Factors influencing a specific pathologic diagnosis of non-small-cell lung carcinoma

INTRODUCTION

Historically, a non-small-cell lung carcinoma diagnosis, without pathologic subclassification, provided sufficient information to guide therapy. Evidence now demonstrates that pathologic subtype classification is central in selecting optimal treatment. This review aimed to identify factors associated with a specific pathologic diagnosis.

METHODS

All nonoperative cases of non-small-cell lung carcinoma (NSCLC) referred to the medical oncology divisions of the Ottawa Hospital Cancer Centre (2008) and Princess Margaret Hospital, Toronto (2007-2010) were identified. The charts were reviewed for demographics, diagnostic methods, and final diagnosis. Logistic regression was performed to identify variables associated with a specific diagnosis.

RESULTS

Of 739 patient records analyzed, 377 (51%) were men, 299 (40%) were aged over 70 years, and 510 (69%) had an Eastern Cooperative Oncology Group performance status of 0-2. Three hundred and eighty five (52%) of patients were diagnosed in a tertiary academic center. The lung primary was sampled in 503 (68%) of patients. Computed tomography-guided biopsy (n = 370, 50%) and bronchoscopy (n = 179, 24%) were the most common techniques. Four hundred and seventy seven (65%) of biopsies were cytologic specimens alone, and immunohistochemistry was performed in 337 (46%) of cases. The most common diagnoses were adenocarcinoma (n = 338, 46%), NSCLC not otherwise specified (n = 254, 34%), and squamous cell carcinoma (n = 115, 16%). Overall, 456 (62%) of patients received a specific pathologic diagnosis. Factors significantly associated with attaining a specific pathologic diagnosis were diagnosis outside an academic center (adjusted odds ratios [OR] 2.1 [95% CI, 1.41-3.14]; P = .0003), histologic laboratory samples (adjusted OR 1.58 [95% CI, 1.003-2.49]; P = .049), and immunohistochemical testing (adjusted OR 1.82 [95% CI, 1.25-2.70], P = .0021).

CONCLUSIONS

A significant minority of patients with NSCLC do not receive a specific pathologic diagnosis. In an era of individualized medicine, this may potentially impact optimal clinical management.

Two microRNA panels to discriminate three subtypes of lung carcinoma in bronchial brushing specimens

RATIONALE

Effective treatment for lung cancer requires accuracy in subclassification of carcinoma subtypes.

OBJECTIVES

To identify microRNAs in bronchial brushing specimens for discriminating small cell lung cancer (SCLC) from non-small cell lung cancer (NSCLC) and for further differentiating squamous cell carcinoma (SQ) from adenocarcinoma (AC).

METHODS

Microarrays were used to screen 723 microRNAs in laser-captured, microdissected cancer cells from 82 snap-frozen surgical lung specimens. Quantitative reverse-transcriptase polymerase chain reaction was performed on 153 macrodissected formalin-fixed, paraffin-embedded (FFPE) surgical lung specimens to evaluate seven microRNA candidates discovered from microarrays. Two microRNA panels were constructed on the basis of a training cohort (n = 85) and validated using an independent cohort (n = 68). The microRNA panels were applied as differentiators of SCLC from NSCLC and of SQ from AC in 207 bronchial brushing specimens.

MEASUREMENTS AND MAIN RESULTS

Two microRNA panels yielded high diagnostic accuracy in discriminating SCLC from NSCLC (miR-29a and miR-375; area under the curve [AUC], 0.991 and 0.982 for training and validation data set, respectively) and in differentiating SQ from AC (miR-205 and miR-34a; AUC, 0.977 and 0.982 for training and validation data set, respectively) in FFPE surgical lung specimens. Moreover, the microRNA panels accurately differentiated SCLC from NSCLC (AUC, 0.947) and SQ from AC (AUC, 0.962) in bronchial brushing specimens.

CONCLUSIONS

We found two microRNA panels that accurately discriminated between the three subtypes of lung carcinoma in bronchial brushing specimens. The identified microRNA panels may have considerable clinical value in differential diagnosis and optimizing treatment strategies based on lung cancer subtypes.

c-MET/phospho-MET protein expression and MET gene copy number in non-small cell lung carcinomas

INTRODUCTION

The hepatocyte growth factor/MET pathway has been shown to cause tumor progression in several types of carcinomas. The aim of this study was to examine the correlations between c-MET/phospho-MET expression as well as MET gene copy number alterations and overall survival (OS) in non-small cell lung carcinomas (NSCLCs).

METHODS

We analyzed 906 NSCLCs including 704 adenocarcinomas (ADCs), 150 squamous cell carcinomas (SCCs), 43 sarcomatoid carcinomas, and 9 large cell carcinomas. The mutational status of epidermal growth factor receptor and K-ras and anaplastic lymphoma kinase rearrangements were retrospectively examined. We performed immunohistochemistry to detect c-MET/phospho-MET expression and MET gene copy number using bright-field in situ hybridization (BISH).

RESULTS

c-MET/phospho-MET expression and MET BISH positivity were observed in 22.2%, 5.6%, and 10.9% of NSCLCs, respectively; they were more prevalent in ADCs (27.3%, 6.9%, and 11.5%, respectively) and sarcomatoid carcinomas (20.9%, 9.3%, and 36.6%, respectively) than in SCCs and large cell carcinomas. Among ADCs, poorly differentiated cases exhibited c-MET expression and MET BISH positivity more commonly than well-differentiated ones. An analysis of all patients revealed that c-MET/phospho-MET expression and MET BISH positivity were not correlated with OS. However, when SCC cases were excluded, both univariate (p=0.019) and multivariate (p=0.020) analyses revealed a significant correlation between MET BISH positivity and OS.

CONCLUSIONS

c-MET/phospho-MET expression and MET BISH positivity differed according to histological type. Among ADCs, c-MET expression and MET BISH positivity were more common in poorly differentiated cases. MET BISH positivity was an independent prognostic factor in nonsquamous NSCLCs.

Are EUS-FNA and EBUS-TBNA specimens reliable for subtyping non-small cell lung cancer?

With endosonography, the diagnosis and staging of non-small cell lung cancer (NSCLC) increasingly relies on small samples. The discrimination between squamous and non-squamous subtypes is now important for therapy tailoring. We analyzed the agreement between fine needle aspirates obtained by endosonography and matched biopsy samples for subtyping NSCLC. Patients with a positive endoscopic fine needle aspirate and a matched biopsy were identified. The level of diagnostic agreement was estimated with biopsy samples as golden standard. In 951 patients investigated with endosonography, we identified 92 with NSCLC on the positive fine needle aspirate and on the matched biopsy. Squamous cell carcinoma was diagnosed in 34 (37%) and 44 (48%) of fine needle aspirate and biopsy samples; while non-squamous carcinoma was diagnosed in 58 (63%) and 48 (52%) respectively. The agreement between needle aspirate and biopsy for the subtyping of NSCLC was 76% (kappa=0.52). In cases with cell block preparation, the agreement for subtyping was 96% (kappa=0.91) vs 69% (kappa=0.39) in cases without cell blocks. Therefore, the diagnostic agreement between endosonographic fine needle aspirates and biopsy specimens for subtyping NSCLC is moderate with a disagreement in 1 out of 4 patients. However, cell block preparation increased the agreement and thus the reliability of the fine needle specimens obtained during endosonography, for subtyping NSCLC considerably. In conclusion, for patients with NSCLC in whom subtyping is relevant, a diagnostic technique yielding larger samples (FNA with cell block preparation or biopsies) should be preferred.

Personalized medicine for lung cancer: new challenges for pathology

Recent advances in non-small-cell lung cancer (NSCLC) therapy mean the relatively simple discrimination between small-cell and 'non-small-cell' carcinoma is insufficient to determine the best treatment for individual patients. Safety, efficacy and prescribing requirements mandate more specific subtyping of NSCLC for several new drugs: practice made difficult by the tumour heterogeneity combined with the paucity of tissue in most diagnostic samples. Immunohistochemical approaches have emerged as accurate predictors of probable tumour histotype. P63 and/or cytokeratins 5 and 6 and thyroid transcription factor 1 (TTF1) are among the best predictors, respectively, of squamous and adenocarcinoma histology. Molecular characteristics may predict response to both newer molecular targeted agents and traditional cytotoxic agents. Specific mutations in the epidermal growth factor receptor (EGFR) gene as predictors of response to EGFR tyrosine kinase inhibitors (erlotinib, gefitinib) is the first example of markers which predict response to targeted agents. Actual drug targets [e.g. thymidilate synthase (TS) - pemetrexed] or markers of the tumour's ability to repair cytotoxic drug-induced damage [e.g. excision repair cross-complementation group 1 (ERCC1) - cisplatin] may well also complement NSCLC diagnosis. This extended diagnostic requirement from increasingly limited material provided by minimally invasive biopsy techniques poses major challenges for pathology.

A systematic review of the interobserver variability for histology in the differentiation between squamous and nonsquamous non-small cell lung cancer

INTRODUCTION

The importance of identifying non-small cell lung cancer (NSCLC) histologic subtype has increased recently because of the development of target-specific chemotherapeutic agents. This systematic review was undertaken to examine the interobserver variability for histology in differentiating between subtypes of NSCLC, specifically the ability to differentiate squamous from nonsquamous histology.

METHODS

A systematic literature search was undertaken to identify studies that evaluated the reproducibility of histologic diagnosis by pathologists in their reporting of NSCLC subtypes. Studies were screened using a priori defined eligibility criteria. The National Health and Medical Research Council diagnostic levels of evidence were applied and quality assessed using the Quality Assessment of Diagnostic Accuracy Studies tool. Data were extracted and reanalyzed to permit comparison of agreement in nonsquamous and squamous cell carcinoma by 2 × 2 tables. Percentage agreement and kappa statistics were calculated for each included study.

RESULTS

Out of 1480 articles identified through the literature search, six were eligible for inclusion. The percentage agreement for all subtypes of NSCLC in the included studies ranged from 67.1 to 89.6% (κ, 0.42-0.84). Based on the primary reanalysis of data (reanalysis 1), agreement between pathologists in differentiating nonsquamous and squamous histology ranged from 77.0 to 94.2% (κ = 0.48-0.88) indicating a moderate to high level of agreement.

CONCLUSION

The reasonably high agreement and kappa statistics for the included studies suggest that pathologists can reproducibly differentiate between nonsquamous and squamous NSCLC. This is clinically important in guiding oncologist decision making in choosing the most appropriate therapy for their patients.

Gefitinib as first-line treatment for patients with advanced non-small-cell lung cancer with activating Epidermal Growth Factor Receptor mutation: implications for clinical practice and open issues

Randomized trials comparing gefitinib with chemotherapy as first-line treatment in patients with EGFR mutated advanced NSCLC support gefitinib as a new, highly effective treatment option in this setting. However, its use in clinical practice has several relevant implications and open issues. In order to choose the best treatment, a molecular characterization is now mandatory, as part of baseline diagnostic procedures. Every effort should be made in order to obtain sufficient tissue. If a clinical enrichment has to be performed for selecting patients to test for EGFR mutation, a reasonable proposal is to test all non-squamous tumors, and patients with squamous tumors only if never smokers. In patients with EGFR mutated tumor, one major issue is the decision about immediate use of gefitinib as first-line, or after failure of standard chemotherapy. First-line gefitinib, compared to chemotherapy, is associated with longer progression-free survival, higher response rate, better toxicity profile and quality of life, and its administration as first-line warrants that all patients have the chance of receiving an EGFR inhibitor. Evidence about the efficacy of erlotinib in the same setting will be soon available, however, at the moment, there are no direct comparisons between gefitinib and erlotinib in EGFR mutated patients. Treatment with gefitinib is usually well tolerated. Typical side effects in most cases are of mild to moderate intensity, and usually manageable with temporary interruption of treatment. When indicated gefitinib appears feasible also in special populations, like elderly or unfit patients, characterized by a significantly poorer risk/benefit ratio with standard chemotherapy. Personalized medicine for patients with lung cancer is now a reality, and patients with EGFR mutation should be treated with first-line EGFR tyrosine kinase inhibitor.