Molecular margin analysis predicts local recurrence after sublobar resection of lung cancer

DNA methylation patterns at and beyond the histological margin of early-stage invasive lung adenocarcinoma radiologically manifested as pure ground-glass opacity

Background

Early-stage lung cancers radiologically manifested as ground-glass opacities (GGOs) have been increasingly identified, among which pure GGO (pGGO) has a good prognosis after local resection. However, the optimal surgical margin is still under debate. Precancerous lesions exist in tumor-adjacent tissues beyond the histological margin. However, potential precancerous epigenetic variation patterns beyond the histological margin of pGGO are yet to be discovered and described.

Results

A genome-wide high-resolution DNA methylation analysis was performed on samples collected from 15 pGGO at tumor core (TC), tumor edge (TE), para-tumor tissues at the 5 mm, 10 mm, 15 mm, 20 mm beyond the tumor, and peripheral normal (PN) tissue. TC and TE were tested with the same genetic alterations, which were also observed in histologically normal tissue at 5 mm in two patients with lower mutation allele frequency. According to the difference of methylation profiles between PN samples, 2284 methylation haplotype blocks (MHBs), 1657 differentially methylated CpG sites (DMCs), and 713 differentially methylated regions (DMRs) were identified using reduced representation bisulfite sequencing (RRBS). Two different patterns of methylation markers were observed: Steep (S) markers sharply changed at 5 mm beyond the histological margin, and Gradual (G) markers changed gradually from TC to PN. S markers composed 86.2% of the tumor-related methylation markers, and G markers composed the other 13.8%. S-marker-associated genes enriched in GO terms that were related to the hallmarks of cancer, and G-markers-associated genes enriched in pathways of stem cell pluripotency and transcriptional misregulation in cancer. Significant difference in DNA methylation score was observed between peripheral normal tissue and tumor-adjacent tissues 5 mm further from the histological margin (p < 0.001 in MHB markers). DNA methylation score at and beyond 10 mm from histological margin is not significantly different from peripheral normal tissues (p > 0.05 in all markers).

Conclusions

According to the methylation pattern observed in our study, it was implied that methylation alterations were not significantly different between tissues at or beyond P10 and distal normal tissues. This finding explained for the excellent prognosis from radical resections with surgical margins of more than 15 mm. The inclusion of epigenetic characteristics into surgical margin analysis may yield a more sensitive and accurate assessment of remnant cancerous and precancerous cells in the surgical margins.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13148-021-01140-3.

Optimal margins for early stage peripheral lung adenocarcinoma resection

Background

A pathologically confirmed negative margin is required when performing sublobar resection in patients with early stage peripheral lung adenocarcinoma. However, the optimal margin distance to ensure complete tumor resection while preserving healthy lung tissue remains unknown. We aimed to establish a reliable distance range for negative margins.

Methods

A total of 52 intraoperative para-cancer tissue specimens from patients with peripheral lung adenocarcinoma with pathological tumors ≤2 cm in size were examined. Depending on the distance from the tumor edge (D), the para-cancer tissues were divided into the following five groups: D < 0.5 cm (group I); 0.5 cm ≤ D < 1.0 cm (group II); 1.0 cm ≤ D < 1.5 cm (group III); 1.5 cm ≤ D < 2.0 cm (group IV); and D ≥ 2.0 cm (group V). During pathological examination of the specimens under a microscope, the presence of atypical adenomatous hyperplasia or more severe lesions was considered unsafe, whereas the presence of normal lung tissue or benign hyperplasia was considered safe.

Results

Group V, in which the margin was the farthest from the tumor edge, was the safest. There were significant safety differences in between groups I and V (χ² = 26.217, P < 0.001). Significant safety differences also existed between groups II and V (χ² = 9.420, P < 0.005). There were no significant safety differences between group III or IV and group V (P = 0.207; P = 0.610).

Conclusions

We suggest that when performing sublobar resection in patients with early stage peripheral lung adenocarcinoma with pathological tumor sizes ≤2 cm, the resection margin distance should be ≥1 cm to ensure a negative margin.

Molecular Analysis of Oncogenic Mutations in Resected Margins by Next-Generation Sequencing Predicts Relapse in Non-Small Cell Lung Cancer Patients

Objective

To investigate the genetic mutations in both tumor and marginal tissues in patients with non-small cell lung cancer (NSCLC), and to evaluate the potential prognostic value in patients with margins gene positive.

Methods

Next-generation sequencing (NGS) technique was used to detect genetic mutation in tumor and marginal tissues of the bronchus in 88 patients with NSCLC. Correlation of genetic mutations with pathology, lymph node metastasis, disease-free survival and overall survival was analyzed.

Results

Of the 88 patients, 83 cases (94.3%) had gene mutations in the tumor samples and 12 cases (13.6%) had genetic alterations in their margins. Most of the gene mutations detected were cancer drivers. Six common driver genes between tumor and marginal tissues were identified, including EGFR, TP53, CDKN2A, CTNNB1, BRAF, and NF1. Kaplan–Meier analysis revealed that the median disease-free survival (DFS) was significantly shorter in patients with detectable gene mutations in marginal tissues compared with patients without mutations in margins (30.7 versus 24.4 months, log-rank χ² = 4.78, P =0.029). Consistently, a shorter median OS was observed in patients harboring gene mutations in margins compared with patients with no mutations in margins (49.1 versus 32.2 months, log-rank χ² = 3.669, P =0.055).

Conclusion

These findings identify the presence of oncogenic alterations in microscopically negative margins in NSCLC patients associated with elevated risk of relapse and shorter survival time. Thus, examination of microscopically negative margins by NGS represents a valuable approach to predict the clinical outcome of NSCLC patients.

Prediction of Recurrence With KRAS Mutational Burden Using Ultrasensitive Digital Polymerase Chain Reaction of Radial Resection Margin of Resected Pancreatic Ductal Adenocarcinoma

OBJECTIVE

Although complete surgical resection is the only curative method for pancreatic cancer, the radial resection margins of pylorus-preserving pancreaticoduodenectomy specimens might be underevaluated.

METHODS

KRAS mutation was assessed with droplet digital polymerase chain reaction on cells collected from the radial resection margins of 81 patients, and the results were compared with those of conventional pathologic resection margin (pRM) evaluation.

RESULTS

KRAS mutation was detected in 76 patients (94%), and molecular resection margin (mRM) positivity defined by a KRAS mutation rate of 4.19% or greater was observed in 18 patients (22%). Patients with mRM-positive had significantly worse recurrence-free survival (RFS) than those with mRM-negative in entire groups (P = 0.008) and in subgroups without chemotherapy or radiation therapy (all, P < 0.001). When combined pRMs-mRMs were evaluated, patients with combined pRM-mRM-positive (either pRM- or mRM-positive) had significantly worse RFS than those with combined resection margin-negative (both pRM and mRM negative) by univariate (P = 0.002) and multivariate (P = 0.03) analyses.

CONCLUSIONS

KRAS mutational analysis with ultrasensitive droplet digital polymerase chain reaction of the radial resection margin in pancreatic cancer patients who underwent pylorus-preserving pancreaticoduodenectomy can provide more accurate information on RFS by using alone or in combination with conventional pRM evaluation, especially in patients without chemotherapy or radiation therapy.

Targeted next-generation sequencing reveals recurrence-associated genomic alterations in early-stage non-small cell lung cancer

Purpose

The identification of genomic alterations related to recurrence in early-stage non-small cell lung cancer (NSCLC) patients may help better stratify high-risk individuals and guide treatment strategies. This study aimed to identify the molecular biomarkers of recurrence in early-stage NSCLC.

Results

Of the 42 tumors evaluable for genomic alterations, TP53 and EGFR were the most frequent alterations with population frequency 52.4% and 50.0%, respectively. Fusion genes were detected in four patients, which had lower mutational burden and relatively better genomic stability. EGFR mutation and fusion gene were mutually exclusive in this study. CDKN2A, FAS, SUFU and SMARCA4 genomic alterations were only observed in the relapsed patients. Increased copy number alteration index was observed in early relapsed patients. Among these genomic alterations, early-stage NSCLCs harboring CDKN2A, FAS, SUFU and SMARCA4 genomic alterations were found to be significantly associated with recurrence. Some of these new findings were validated using The Cancer Genome Atlas (TCGA) dataset.

Conclusions

The genomic alterations of CDKN2A, FAS, SUFU and SMARCA4 in early-stage NSCLC are found to be associated with recurrence, but confirmation in a larger independent cohort is required to define the clinical impact.

Materials and Methods

Paired primary tumor and normal lung tissue samples were collected for targeted next-generation sequencing analysis. A panel targets exons for 440 genes was used to assess the mutational and copy number status of selected genes in three clinically relevant groups of stage I/II NSCLC patients: 1) Early relapse; 2) Late relapse; and 3) No relapse.

[Progress of Lung Margin During Sublobar Resection for Early-staged Non-small Cell Lung Cancer]

近年来随着低剂量计算机断层扫描(low-dose computed tomography, LDCT)、高分辨率CT(high-resolution CT, HRCT)的普及, 早期非小细胞肺癌的发现比率不断上升, 越来越多的胸外科医生探索手术方式的改良, 推动手术切除范围向更加合理的方向进展。临床研究发现肺切缘阴性较阳性有更低的局部肿瘤复发率, 因此亚肺叶切除术治疗早期肺癌术中保证肺切缘阴性具有重要的临床意义, 本文将就这一领域研究现状和进展作一综述。

Detection of oncogenic mutations in resected bronchial margins by next-generation sequencing indicates early relapse in stage IA lung adenocarcinoma patients

Stage I non-small cell lung cancer (NSCLC) patients experience a relatively high rate of recurrence, ranging from about 30-35%. We hypothesized that this elevated risk of recurrence is due to the presence of tumor cells at bronchial margins which was undetected by conventional light microscopy. Patients with clinical stage IA (T1N0M0) NSCLC were enrolled in this study, which included 8 early-relapse(ER) and 6 no-relapse(NR) patients. Primary tumor, bronchial margin, and normal lung tissues were collected and sent to a central site for targeted next-generation sequencing analysis. All of the patients were lung adenocarcinoma. Gene mutations were identified in all tumor tissue samples (100%). Oncogenic mutations were identified in 87.5%(7/8) bronchial margins of early relapse patients, whereas only 16.7%(1/6) no-relapse (NR) patient of marginal tissue had identified gene mutation. Additionally, concordance between primary tumor and bronchial margins was relatively high, with 4 of 8 (50%) ER patients having at least one identical mutation. Moreover, according to the gene mutation status in marginal tissue, 87.5% (7/8) of patients with at least one gene mutation in the bronchial margins had local recurrence or metastasis, whereas only 16.7% (1/6) of patients without any mutation detected had signs of relapse, the recurrence rate was significantly higher than that of the negative mutation margin group ((p (log-rank) = 0.023). The existence of oncogenic mutations in bronchial margins may represent occult residual tumor and elevated risk of recurrence in early stage NSCLC patients. Thus, assessing molecular status in bronchial margins may help identify patients who might benefit from extensive surgery or adjuvant treatment.

Low Frequency of p53AND k-ras Codon 12 Mutations in Non-Small Cell Lung Carcinoma(NSCLC) Tumors and Surgical Margins

Aims and Background

Lung cancer is one of the most common cancers and has became a predominant cause of cancer-related death throughout the world. The k-ras codon 12 mutation, which is the most common lung cancer mutation, is found in 15 to 30% of all lung cancers. Furthermore, the p53 gene has a very important role in the biological properties of tumor cells, and it is mutated in about 50% of non-small cell lung cancers. Residual tumor cells remain in surgical margins diagnosed as tumor free by histopathological techniques, and they can play a role in forming any local recurrence. Molecular methods may be exploited that are sensitive enough to detect small numbers of tumor cells.

Methods

In the present study, we examined p53 gene mutations and k-ras codon 12 mutations from the tumor samples and surgical margins of 34 non-small-cell lung cancer patients. P53 gene mutations were analyzed by single strand conformational polymorphism analysis, heterodublex analysis and DNA sequencing. K-ras codon 12 mutations were analyzed by the mutagenic PCR-restricted fragment length polymorphism method.

Results

A p53 mutation was detected only in primary tumors of 3 out of 34 patients (8.82%). These mutations were clustered in exon 5. Moreover, a k-ras codon 12 mutation was detected in both the primary tumor and the surgical margin tissues of 2 out of 34 patients (5.88%).

Conclusions

The detected mutation rate was low, in the range given in the literature. We think that different mechanisms related to other genes and individual genetic differences might play a role in cancer formation in our study group. We believe that molecular studies are necessary to identify biomarkers and to determine genetic alterations in histopathologically normal surgical margins.

Relationship between EGFR gene mutation and local metastasis of resectable lung adenocarcinoma

Background

Resectable lung adenocarcinoma is dominated by peripheral distribution, and surgical resection is the main treatment protocol. However, high recurrence rate remains after surgery. Lung adenocarcinoma with epidermal growth factor receptor (EGFR) mutation has strong invasion ability, but the effects of this mutation on local invasion in early lung adenocarcinoma have been rarely studied. This study aimed to assess the effects of EGFR mutation on local invasion in resectable lung adenocarcinoma.

Methods

A retrospective analysis of 103 patients clinically diagnosed with peripheral lung adenocarcinoma was included. They underwent preoperative bronchoscopy, which indicated grades 2 or 3 bronchial involvement (lumen of the lobe or segment). The associations of EGFR mutation with pleural invasion, endobronchial metastasis, and lymph node metastasis were analyzed according to pathologies of pleural invasion and lymph node metastasis, as well as EGFR gene mutation detected by postoperative pathological specimens. Statistical analyses were performed by unpaired Chi-square test using the SPSS16.0 software.

Results

In patients with EGFR mutation, pleural invasion, endobronchial metastasis, and lymph node metastasis rates were 62.5, 39.1, and 34.4%, respectively, indicating statistically significant differences (p = 0.003). Meanwhile, the pleural invasion rate in patients with wild-type EGFR was 43.6%, significantly reduced compared with patients with mutated EGFR (62.5%; p = 0.018). In addition, the endobronchial metastasis rate in patients with wild-type EGFR was 17.9%, significantly lower than in patients with EGFR mutation (39.1%; p = 0.005). However, lymph node metastasis rates were similar between EGFR mutated and wild-type patients (34.4 vs 25.6%, respectively, p > 0.05).

Conclusions

Early resectable lung adenocarcinoma patients with EGFR mutation showed a higher rate of local invasion compared with those harboring wild-type EGFR. This finding provides a basis for improved therapy.

Trial registration

This study was supported by Project of Medical and Health Science Technology in Shandong Province (2015WS0376)

Prognostic value of molecular events from negative surgical margin of non-small-cell lung cancer

It is hypothesized that the molecular status in negative surgical margin (NSM) is associated with prognosis of cancer patients. In this study, the prognostic relevance of Epithelial-to-Mesenchymal Transition (EMT) molecular events in NSMs in patients with NSCLC was investigated. EMT model was developed, in which the mesenchymal transition of human immortalized bronchial epithelial cell line was induced by TGF-beta1. Gene expression of EMT-induced cells and NSMs from 60 lung squamous cell carcinoma (SCC) patients was profiled by microarray and validated by quantitative RT-PCR. Two independent cohorts (lung SCC, n = 50; NSCLC, n = 54) were employed to validate the prognostic value of candidate genes. A set of 1490 genes were identified in EMT model in vitro. An EMT-like gene-expression pattern by 33 essential genes was optimized in NSMs, and was significantly associated with tumor progression. The 33 genes also exhibited a site-dependent field cancerization effect in the normal-appearing airways adjacent to NSCLCs. In the independent lung SCC cohort, the EMT-like active pattern indicated poor outcome of patients (n = 50, log-rank p = 0.009). Furthermore, in the NSCLC cohort, patients with EMT-like active pattern had shorter predictive survival time (n = 54, log-rank p = 0.02). In conclusion, the existence of EMT-like gene expression in NSMs, may play critical role in tumor progression and be a potential biomarker for prognosis in patients with NSCLC.

Rapid Intraoperative Molecular Characterization of Glioma

IMPORTANCE

Conclusive intraoperative pathologic confirmation of diffuse infiltrative glioma guides the decision to pursue definitive neurosurgical resection. Establishing the intraoperative diagnosis by histologic analysis can be difficult in low-cellularity infiltrative gliomas. Therefore, we developed a rapid and sensitive genotyping assay to detect somatic single-nucleotide variants in the telomerase reverse transcriptase (TERT) promoter and isocitrate dehydrogenase 1 (IDH1).

OBSERVATIONS

This assay was applied to tissue samples from 190 patients with diffuse gliomas, including archived fixed and frozen specimens and tissue obtained intraoperatively. Results demonstrated 96% sensitivity (95% CI, 90%-99%) and 100% specificity (95% CI, 95%-100%) for World Health Organization grades II and III gliomas. In a series of live cases, glioma-defining mutations could be identified within 60 minutes, which could facilitate the diagnosis in an intraoperative timeframe.

CONCLUSIONS AND RELEVANCE

The genotyping method described herein can establish the diagnosis of low-cellularity tumors like glioma and could be adapted to the point-of-care diagnosis of other lesions that are similarly defined by highly recurrent somatic mutations.

NOVA1 inhibition by miR-146b-5p in the remnant tissue microenvironment defines occult residual disease after gastric cancer removal

Occult residual disease in remnant tissues could be the cause of tumor relapse. To identify signal molecules and target cells that may be indicative of occult residual disease within a remnant microenvironment, proximal resection margin tissues of gastric cancers were used, as these correspond to the nearest remnant tissues after gastrectomy. Increased miR-146b-5p in the remnant microenvironment was determined to be a strong risk factor for tumor relapse and poor survival rate. NOVA1, a target gene of miR-146b-5p, was decreased in remnant tissues of patients with a poor prognosis. NOVA1 was enriched in stromal spindle cells such as fibroblasts within normal tissues. In non-neoplastic inflammation, such as gastritis, NOVA1 was highly enriched in T lymphocytes and stromal spindle cells, while expression of this protein was frequently decreased in those types of cells within gastric cancer tissues. Particularly, decreased NOVA1 in T cells within the gastric cancer tissues was correlated with decreased FOXP3-positive regulatory T cells and was associated with poor patient prognosis. In vitro analysis showed that the NOVA1 gene was inhibited by miR-146b-5p. In immune cells as well as stromal spindle cells, decreased NOVA1, possibly inhibited by miR-146b-5p, is a candidate biomarker predicting poor prognosis of gastric cancer patients and is also a biomarker of occult residual disease in remnant tissues after gastric cancer removal.

Clinical implications of positive margins following non-small cell lung cancer surgery

Positive margins following pulmonary resection of non-small cell lung cancer (NSCLC) occur in approximately 5-15% of patients undergoing a curative procedure. The presence of positive margins negatively impacts long-term outcomes by setting the stage for local and potentially distant disease recurrence. Despite major clinical ramifications, there are very few dedicated reports that examine the implications of positive margins following surgery for NSCLC. Furthermore, published series are typically retrospective studies from single institutions. In this review we analyze published data with special consideration of four pertinent questions: (i) what are the long term outcomes of a positive margin following pulmonary resection?, (ii) is intraoperative margin assessment by frozen section reliable?, (iii) what is the optimal distance of the tumor margin to the surgical margin?, and (iv) should adjuvant chemotherapy and/or radiation therapy be used in the setting of a positive surgical margin?

A new genotyping method for detecting low abundance single nucleotide mutations based on gap ligase chain reaction and quantitative PCR assay

We tested applicability of a new genotyping technique to detect a low abundance CD17 (A → T) mutation of β-globin gene. The technique utilized a combined gap ligase chain reaction (Gap-LCR) and quantitative PCR (qPCR) methods. One pair of Gap-LCR primers was modified by adding specific sequences to the 5' end of the upstream and the 3' end of the downstream primer which served as a combining sequence for qPCR. First, specific mutation is detected using Gap-LCR; then, ligation products are detected by qPCR. Our results show that the amount of LCR products is directly proportional to the amount of template DNA. We further demonstrate that this technique detects a low abundance mutant DNA with a mutant/normal allele ratio as low as 1:10000. This technique was applied to detect a paternally inherited CD17 mutation from 53 maternal plasma samples. The results were consistent with those obtained by PCR/reverse dot blot of amniotic fluid cell DNA. In conclusion, by combining Gap-LCR and qPCR technology we successfully established a highly sensitive technique to detect low abundance point mutations. This technique can be applied to detect fetal DNA point mutation in maternal plasma.

Clinical implications of the margin cytology findings and margin/tumor size ratio in patients who underwent pulmonary excision for peripheral non-small cell lung cancer

PURPOSE

A pulmonary wedge resection is useful for the treatment of peripheral non-small cell lung cancer (NSCLC). The margin/tumor size ratio (M/T) is a predictor of positive margin cytology findings in these procedures, although the long-term clinical implications remain unclear. This relationship was investigated in this study.

METHODS

Thirty-seven cases with a high surgical risk without additional pulmonary resection were selected from those accrued in a multicenter prospective study of optimal margin distance for pulmonary excision of peripheral NSCLC and followed for more than 5 years (range 5.3-14 years).

RESULTS

Both the M/T and margin cytology findings were indicators of cancer recurrence and survival. All seven cases of surgical margin recurrence had a cytology-positive surgical margin. The 5-year survival rate was 54.2% (n = 24) for M/T < 1 and 84.6% for M/T ≥ 1 (n = 13, P = 0.05), while it was 38.5% for positive margin (n = 13) and 79.2% for negative margin (n = 24) cases (P = 0.001). In addition, the margin cytology findings were an independent prognostic factor.

CONCLUSION

A pulmonary wedge resection for peripheral NSCLC should result in a negative malignant margin, which might be obtained from a sufficient tumor margin ratio of M/T ≥ 1.

Expression of p53, Ki-67 and c-Myc proteins is predictive of the surgical molecular margin in colorectal carcinoma

Surgical resection is the mainstay of treatment for colorectal carcinoma, however, the overall survival is modest due to frequent local recurrence from residual cancer cells after "curative" resection. Therefore, the status of surgical margin (tumor free or positive) has a significant influence on patient's survival. The difference in molecular profile between mucosa neighboring tumor lesions and remote area (surgical margin) may aid in evaluating resection status. 44 colorectal tumor tissues with corresponding adjacent non-neoplastic mucosa (within 3 cm from tumor tissues), and 110 tumor tissues with corresponding surgical margin mucosa (5 cm from tumor tissues) were randomly collected, fixed in 10% formalin and followed by embedding in paraffin. And the expression of p53, Ki-67 and c-Myc were investigated by tissue microarray (TMA) and immunohistochmistry. The expression of p53, Ki-67 and c-Myc were decreased in both adjacent non-neoplastic mucosa and mucosa of surgical margin, comparing to their expression in corresponding cancer cells. Furthermore, the expression of these proteins in mucosa of remote area (surgical margin) was significantly lower than those adjacent to tumor lesions. The expression of p53, Ki-67 and c-Myc in mucosa can be used as molecular marker for assessing surgical margin status in colorectal carcinoma.

Safety distance in the resection of colorectal lung metastases: a prospective evaluation of satellite tumor cells with immunohistochemistry

OBJECTIVE

After complete pulmonary metastasectomy of colorectal lung metastases, tumor recurrence at the site of former resection develops in some patients. Well-described risk factors for local recurrence in the lung include incomplete resection and aerogenous spread of floating cancer cell clusters. The aim of this study was to describe the distribution and frequency of satellite cancer cells or clusters in resected tissue to deduce recommendations for safety margins in the future.

METHODS

Seventeen colorectal metastases from 10 patients were processed. Evaluation for pattern of growth, satellite cancer cells, and inflammatory reaction at the surface of the metastases was performed on 102 sections with CDX2 and cytokeratin 20 stains. The distance between the surface of the nodule and the satellite cancer cell was measured for each satellite and statistically evaluated.

RESULTS

As a pattern of growth, interstitial spread, inflammatory reaction, and lymphangitic spread were observed in 41.2%, 35.3%, and 23.5%, respectively. A total of 205 satellite cancer cells were identified in 16 of 17 metastases with a mean distance to the nodule of 0.99 ± 0.85 mm (range, 0.06-6.43 mm). The percentages of satellite tumor cells that are likely to be found within 1.59 mm, 3.43 mm, and 7.4 mm around the nodule are 68.27%, 95.5%, and 99.73%, respectively.

CONCLUSIONS

Satellite tumor cells, a potential source for local recurrence, are found in a high number around colorectal lung metastases. As a standard of care, a safety distance of 3 mm for small metastases and 8 to 10 mm for larger metastases must be maintained around the lesion to prevent local recurrence.

Personalized Medicine in Non–Small-Cell Lung Cancer: Is KRAS a Useful Marker in Selecting Patients for Epidermal Growth Factor Receptor–Targeted Therapy?

In patients with metastatic colorectal cancer, the predictive value of KRAS mutational status in the selection of patients for treatment with anti–epidermal growth factor (EGFR) monoclonal antibodies is established. In patients with non–small-cell lung cancer (NSCLC), the utility of determining KRAS mutational status to predict clinical benefit to anti-EGFR therapies remains unclear. This review will provide a brief description of Ras biology, provide an overview of aberrant Ras signaling in NSCLC, and summarize the clinical data for using KRAS mutational status as a negative predictive biomarker to anti-EGFR therapies. Retrospective investigations of KRAS mutational status as a negative predictor of clinical benefit from anti-EGFR therapies in NSCLC have been performed; however, small samples sizes as a result of low prevalence of KRAS mutations and the low rate of tumor sample collection have limited the strength of these analyses. Although an association between the presence of KRAS mutation and lack of response to EGFR tyrosine kinase inhibitors (TKIs) has been observed, it remains unclear whether there is an association between KRAS mutation and EGFR TKI progression-free and overall survival. Unlike colorectal cancer, KRAS mutations do not seem to identify patients who do not benefit from anti-EGFR monoclonal antibodies in NSCLC. The future value of testing for KRAS mutational status may be to exclude the possibility of an EGFR mutation or anaplastic lymphoma kinase translocation or to identify a molecular subset of patients with NSCLC in whom to pursue a drug development strategy that targets the KRAS pathway.

Molecular analysis of tumor margins by MALDI mass spectrometry in renal carcinoma

The rate of tumor recurrence post resection suggests that there are underlying molecular changes in nearby histologically normal tissue that go undetected by conventional diagnostic methods that utilize contrast agents and immunohistochemistry. MALDI MS is a molecular technology that has the specificity and sensitivity to monitor and identify molecular species indicative of these changes. The current study utilizes this technology to assess molecular distributions within a tumor and adjacent normal tissue in clear cell renal cell carcinoma biopsies. Results indicate that the histologically normal tissue adjacent to the tumor expresses many of the molecular characteristics of the tumor. Proteins of the mitochondrial electron transport system are examples of such distributions. This work demonstrates the utility of MALDI MS for the analysis of tumor tissue in the elucidation of aberrant molecular changes in the tumor microenvironment.

The value of diffusion-weighted imaging in assessing the ADC changes of tissues adjacent to breast carcinoma

Background

To define a threshold value of apparent diffusion coefficient (ADC) with which malignant breast lesions can be distinguished from benign lesions, and to evaluate the ADC change of peri-tumor tissue in breast carcinoma by echo planar-diffusion weighted imaging (EPI-DWI).

Methods

57 breast lesions were scanned by routine MRI and EPI-DWI. The ADC values were compared between malignant and benign lesions. The sensitivity and specificity of EPI-DWI and the threshold ADC value were evaluated by Receiver Operating Characteristic curve (ROC). The ADC values of malignant lesion and layered peri-tumor tissues (from innermost layer 1 to outermost layer 4 with 5 mm every layer) in different directions were compared and the ADC values among different layers were compared.

Results

The ADC value of 35 malignant lesions was statistically lower than that of 22 benign lesions (P < 0.05). In ROC curve, the threshold value was 1.24 +/- 0.25*10E-3 mm²/s (b = 500) or 1.20 +/- 0.25*10E-3 mm²/s (b = 1000). The ADC value of malignant lesions was statistically lower than that of peri-tumor tissues in different directions (P < 0.05). For peri-tumor tissues, the ADC values increased gradually from layer 1 to layer 4 and there was a significant difference between the ADC values of layer 1 and layer 2 (P < 0.05); while from layer 2 outwards, there was no statistical difference among different layers.

Conclusion

ADC value was a sensitive and specific parameter that could help to differentiate benign and malignant breast lesions. ADC changes in tissues adjacent to breast carcinoma could be detected by EPI-DWI, which made EPI-DWI a promising method for helping to determine surgical scope of breast carcinoma.

Cytologically malignant margin without continuous pulmonary tumor lesion: cases of wedge resection, segmentectomy and lobectomy

The surgical margin is usually investigated during the operation using a pathological method, though cytological methods are also used to identify remaining malignant cells. We reviewed cases of pulmonary resection for a malignant tumor. At our institution, an on-site surgical margin examination using a cytological method is mandated for cases of wedge resection and segmentectomy, and an option in lobectomy cases. We examined 21 wedge resection (3 primary lung cancer, 18 metastasis), 17 segmentectomy (13 primary lung cancer, 4 metastasis), and 4 lobectomy (all primarily lung cancer) cases. Six cases showed malignant cells in the surgical margin, of which one had a microscopic skip lesion pattern and five an 'occult' pattern (positive cytology, negative pathology). Cytological malignancy occurred even in cases of wedge resection of a tiny (4 mm in diameter) lesion metastasized from colon cancer, as well as segmentectomy with a sufficient gross margin containing microscopic skip lesions and right middle lobectomy with an additional right upper lobectomy due to two previous cytological malignancies in a residual lobe. Surgical margin cytology revealed remaining malignancy in the residual lobe, which provided important information for deciding additional procedures during surgery.

Role of Sublobar Resection (Segmentectomy and Wedge Resection) in the Surgical Management of Non–Small Cell Lung Cancer

Segmentectomy demands a thorough knowledge of the three-dimensional bronchovascular anatomy of the lung. This anatomic detail makes segmentectomy significantly more challenging than lobectomy. Several principles must be applied when performing segmental lung resection: (1) the surgeon should avoid dissection in a poorly developed fissure, (2) use the transected bronchus as the base of the segmental resection during the division of the lung parenchymal in the intersegmental plane, (3) consider the use of endostapler division of the pulmonary parenchyma to reduce the air leak complications related to "finger fracture" dissection of the intersegmental plane, and (4) consider the use of adjuvant iodine 125 brachytherapy as a means of reducing local recurrence following sublobar resection. Increasing evidence supports the use of anatomic segmentectomy in the treatment of primary lung cancer for appropriately selected patients. This resection approach seems most appropriate in the management of the small (<2 cm in diameter) peripheral stage I NSCLC in which a generous margin of resection can be obtained. Accurate intraoperative nodal staging is important to estimate the relative use of these approaches compared with more aggressive resection and to determine the need for adjuvant systemic therapy if metastatic lymphadenopathy is identified. Future investigations comparing the results of sublobar resection with lobectomy will more clearly define the role of segmentectomy among good-risk patients with clinical stage I NSCLC. At the present time, it seems that sublobar resection is an appropriate therapy for the management of stage I NSCLC identified in the elderly patient, those individuals with significant cardiopulmonary dysfunction, and for the management of peripheral solitary metastatic disease to the lung. Because the primary disadvantage of sublobar resection is that of local recurrence, intraoperative adjuvant iodine 125 brachytherapy may be considered to minimize this local recurrence risk.

Genetic alterations in lung cancer: assessing limitations in routine clinical use

Lung cancer is the most frequent cause of cancer mortality worldwide, responsible for approximately 1.1 million deaths per year. Median survival is short, both as most tumours are diagnosed at an advanced stage and because of the limited efficacy of available treatments. The development of tumour molecular gene- tics carries the promise of altering this state of affairs, as it should lead to a more precise classification of tumours, identify specific molecular targets for therapy and, above all, allow the development of new methods for early diagnosis. Despite numerous studies demonstrating the usefulness of molecular genetic techniques in the study of lung cancer, its routine clinical use in Portugal has, however, been limited. In this study, we used a p53 mutation screen in multi- ple clinical samples from a series of lung cancer patients to attempt to identify the main practical limitations to the integration of molecular genetics in routine clinical practice. Our results suggest that the main limiting factor is the availability of samples with good quality DNA; a problem that could be overcome by alterations in common sample collection and storage procedures.

Sublobar Resections for Lung Cancer

Sublobar resection has been utilized as an alternative to lobectomy for the treatment of early-stage lung cancer in patients with compromised preoperative pulmonary function. Early data have suggested higher rates of local recurrence and increased late mortality for sublobar resection as compared with lobectomy. Subsequent studies have been mixed with respect to outcomes. Here we review the existing literature comparing sublobar resection to lobectomy with respect to oncologic and pulmonary outcomes. We also discuss the effect of adjuvant intraoperative brachytherapy to sublobar resection and summarize ongoing clinical trials that compare sublobar resection to sublobar resection plus adjuvant brachytherapy in the treatment of early-stage lung cancer. Finally, based on the current evidence, we provide recommendations as to when sublobar resection might be considered in the treatment of lung cancer.

Microarray-based molecular margin methylation pattern analysis in colorectal carcinoma

The positive surgical margins are associated with postsurgical recurrence in colorectal carcinoma patients, and molecular margin analysis is considered to be more sensitive in detecting preneoplastic lesions than is conventional histological margin examination. Here, we developed a microarray and established six calibration curves for hMLH1 gene methylation patterns analysis in 20 colorectal resected margin specimens and corresponding tumor tissue specimens as well as four normal tissue specimens. The results indicated that a moderate methylation level (8-42%) was found in 20 surgical margin tissues, extensive methylation (25-58%) was detected in 20 tumor tissues, and little or no methylation was observed in normal tissues. Of the six paired probes, the average methylation levels in 20 tumor tissues were 60, 35, 43, 53, 38, and 27%, whereas the average methylation levels of the six paired probes in 20 surgical margin tissues were 43, 16, 24, 28, 21, and 11%. Thus, this study demonstrated the feasibility of this assay for molecular assessment use. In addition, it will contribute significant information to our understanding of CpG island methylation for cancer diagnosis and postoperative recurrence.

Methylation-based molecular margin analysis in hepatocellular carcinoma

The positive surgical margins are associated with postsurgical recurrence in hepatocellular carcinoma patients, and molecular margin analysis is considered more sensitive in detecting preneoplastic lesions than conventional histological margin examination. To evaluate the feasibility of methylation-based molecular margin analysis in HCC and explore its clinical application, we investigated CDKN2A methylation status in the surgical margins of 20 HCC patients using a nested BS-MSP protocol and compared the methylation patterns in resection margins with those in the corresponding tumor and adjacent nonmalignant tissues. The results showed that a considerable frequency (35%, 7 of 20) of CDKN2A methylation was present in histologically negative margins, and methylation pattern analysis might be valuable for studying the cellular origin of recurrent carcinoma. Therefore, methylation-based molecular surgical margin analysis offers a promising tool in prognosis for HCC patients who underwent hepatectomy.