DNA methylation and miRNA expression in colon adenomas compared with matched normal colon mucosa and carcinomas.

Dysregulation of DNA methylation patterns and non-coding RNA, including miRNAs, has been implicated in colon cancer, and these changes may occur early in the development of carcinoma. In this study, the role of epigenetics as early changes in colon tumorigenesis was examined through paired sample analysis of patient-matched normal, adenoma and carcinoma samples. Global methylation was assessed by genomic 5-methyl cytosine (5-mC) and long interspersed nuclear element-1 (LINE-1) promoter methylation by pyrosequencing. KRAS mutations were also assessed by pyrosequencing. Expression of miRNA, specifically, two microRNA genes-miR-200a and let-7c-was analysed using RT-qPCR. Differences in global methylation in adenomas were not observed, compared with normal tissue. However, LINE-1 methylation was decreased in adenomas (p = .056) and carcinomas (p = .011) compared with normal tissue. Expressions of miRNA, miR-200a and let-7c were significantly higher in adenomas than normal tissues (p = .008 and p = .045 respectively). Thus the significant changes in LINE-1 methylation and microRNA expression in precancerous lesions support an early role for epigenetic changes in the carcinogenic process. Epigenetic characteristics in adenomas may provide potential diagnostic and prognostic therapeutic targets early in cancer development at the adenoma stage.

Evidence for age-related contributions of DNA damage and epigenetics in brain tumorigenesis.

Glioblastoma (GBM) is a highly malignant primary brain tumour displaying rapid cell proliferation and infiltration. GBM primarily occurs at older age; however, younger populations have also been affected. In GBM and other cancers, genetic and epigenetic alterations promote tumorigenesis causing increased cell proliferation and invasiveness. This investigation explored epigenetic events as contributing factors, especially in gliomas that arise in patients aged 40-60 years. Furthermore, DNA damage in tumours with respect to age was assessed. Archival fixed tissues from 88 cases of glioblastoma and adjacent non-malignant tissues were tested. Global methylation and DNA damage were measured using ELISA detection of 5-methyl cytosine and 8-hydroxy guanine, respectively. IDH mutations and CDKN2 promoter hypermethylation were analysed by pyrosequencing. Tumour tissue was hypomethylated compared with non-malignant tissue (P = .001), and there was a trend towards increased methylation with increasing age. There was a significant increase in DNA damage in patients older than forty years compared with those aged forty years or younger (P = .035). CDKN2 promoter methylation levels followed the age trends of global methylation in this patient group. Patients younger than 60 had more frequently mutated IDH (P = .004). Conclusions: The data support the potential of epigenetic factors in promoting tumorigenesis in younger patients, while increased DNA damage contributes to tumorigenesis in the older patients.

Correlation of LINE-1 Hypomethylation With Size and Pathologic Extent of Dysplasia in Colorectal Tubular Adenomas.

INTRODUCTION: Conventional adenomas (tubular adenoma [TA] or tubulovillous adenoma) and sessile serrated lesions (SSLs) are neoplastic precancerous lesions frequently detected in patients undergoing average risk screening colonoscopy and polyp surveillance. Metachronous risk stratification of adenomas is currently limited to histologic features and size of polyps. We report long interspersed nucleotide element-1 (LINE-1) methylation levels in SSL in comparison to TA and the impact of TA size and presence of high-grade dysplasia (HGD) on LINE-1 methylation. METHODS: LINE-1 methylation was assessed by pyrosequencing of bisulfite-converted DNA. We compared LINE-1 methylation between TA and SSL, among varying sizes of TA, and between TA with HGD and low-grade dysplasia (LGD). RESULTS: LINE-1 methylation declined with increasing polyp size in TA when comparing those <5 mm (72.31 ± 6.11), 5 to <10 mm (67.50 ± 7.00), and ≥10 mm (66.75 ± 11.89). There were lower LINE-1 methylation levels in TA with LGD (n = 119) compared with SSLs (n = 29) (69.11 ± 8.62 vs 81.41 ± 2.43, P < 0.001). TA containing HGD (n = 26) had lower LINE-1 methylation levels than those with LGD (n = 119) (59.86 ± 7.93 vs 69.11 ± 8.62, P < 0.001). DISCUSSION: HGD and increasing size of TA/tubulovillous adenoma were associated with lower LINE-1 methylation. This supports a hypothesis that LINE-1 hypomethylation in TAs indicates advancement along the CRC tumorigenesis pathway. Lower LINE-1 methylation and greater variance of global DNA methylation was seen in TA compared with SSL. LINE-1 methylation in adenomas correlates with polyp size and degree of dysplasia and deserves further study as a predictor of metachronous colorectal cancer risk.

A Durable Response to Pembrolizumab in a Patient with Uterine Serous Carcinoma and Lynch Syndrome due to the MSH6 Germline Mutation.

Pembrolizumab, a programmed death 1 ligand (PD-1) checkpoint inhibitor, has elicited responses in mismatch repair (MMR)-deficient advanced solid tumors, leading to its agnostic approval by the US Food and Drug Administration in 2017 when no other therapeutic options are available. However, there are still insufficient data on the response to checkpoint inhibitors in advanced endometrial cancer related to Lynch syndrome (LS) and, specifically, in uterine serous carcinoma, which is uncommon in LS. Here we report a case of metastatic uterine serous carcinoma due to a germline MSH6 mutation (Lynch syndrome) that was discovered because of a patient's tumor MMR deficiency. The patient was started on first-line pembrolizumab in 2018 and sustained a partial response. She remains asymptomatic and progression free for more than 2 years. Tumor sequencing showed a high mutational burden and an upstream somatic mutation in the same gene, p.F1088fs. Immunohistochemical staining was negative for PD-L1 expression. We discuss clinical characteristics of the patient, molecular features of her tumor, and the mechanism of her tumor response. We also discuss the duration of immunotherapy in her case. Our case demonstrated a partial response and a long-term remission from the frontline single-agent pembrolizumab in a woman with metastatic uterine serous carcinoma and Lynch syndrome due to a germline MSH6 gene mutation. Our experience suggests a potential significant clinical benefit of checkpoint inhibitors used as single agents early on in the treatment of MMR-deficient/high microsatellite instability/hypermutated uterine cancers in women with Lynch syndrome. KEY POINTS: Even though checkpoint inhibitors are effective in mismatch repair-deficient endometrial cancer, it is unknown whether the response to them differs between women with endometrial cancer due to germline mutations in a mismatch repair gene (Lynch syndrome) and women with sporadic endometrial cancer. In our case, a patient with Lynch syndrome and recurrent mismatch repair-deficient serous endometrial cancer achieved a durable remission on the first-line therapy with the checkpoint inhibitor pembrolizumab and remains progression free after more than 2 years. Based on our observation and the data, suggesting the stronger immune activation in women with Lynch syndrome-associated endometrial cancer, we propose to use checkpoint inhibitor monotherapy early in the course of their treatment and stratify patients for the presence of Lynch syndrome in clinical trials.

Paired tumor sequencing and germline testing in breast cancer management: An experience of a single academic center.

BACKGROUND: Genetic testing for cancer predisposition is recommended to women with breast cancer who meet the criteria for such testing. After the FDA approvals of the poly ADP ribose polymerase (PARP) inhibitors, olaparib and talazoparib, for treatment of metastatic breast cancer, carrying germline mutations in BRCA1 and BRCA2 genes, the genetic testing result has become critical in their care. With the recent FDA approval of alpelisib for the treatment of PIK3CA-mutated hormone-receptor positive metastatic breast cancer, tumor molecular profiling to identify somatic mutations and potential molecularly targeted agents is increasingly utilized in the treatment of advanced breast cancer. AIM: Combining germline and somatic sequencing (paired testing) offers an advantage over a single technique approach. Our study evaluates the role of paired testing on the management of breast cancer patients. METHODS AND RESULTS: Forty-three breast cancer patients treated at Rush University Medical Center underwent paired germline and somatic variant testing in 2015 to 2017. A retrospective chart review was conducted with the analysis of demographic, clinical, and genomic data. Three actionable germline variants were found in the CHEK2 (2) and ATM (1) genes. 95% of tumors had somatic mutations. Seventy-seven percent of tumors had genomic alterations targetable with agents approved for breast cancer and 88% had molecular targets for agents approved for other cancers. Clinical examples of such use are described and potential future directions of tumor and paired testing are discussed. CONCLUSIONS: Germline variants were present in a relatively small patient group not routinely tested for inherited alterations. Potentially targetable somatic alterations were identified in the majority of breast cancers. Paired testing is a feasible and efficient approach that delivers valuable information for the care of breast cancer patients and eliminates serial testing.

Comparison of Tissue Molecular Biomarker Testing Turnaround Times and Concordance Between Standard of Care and the Biocartis Idylla Platform in Patients With Colorectal Cancer.

OBJECTIVES: Management of colorectal cancer warrants mutational analysis of KRAS/NRAS when considering anti-epidermal growth factor receptor therapy and BRAF testing for prognostic stratification. In this multicenter study, we compared a fully integrated, cartridge-based system to standard-of-care assays used by participating laboratories. METHODS: Twenty laboratories enrolled 874 colorectal cancer cases between November 2017 and December 2018. Testing was performed on the Idylla automated system (Biocartis) using the KRAS and NRAS-BRAF cartridges (research use only) and results compared with in-house standard-of-care testing methods. RESULTS: There were sufficient data on 780 cases to measure turnaround time compared with standard assays. In-house polymerase chain reaction (PCR) had an average testing turnaround time of 5.6 days, send-out PCR of 22.5 days, in-house Sanger sequencing of 14.7 days, send-out Sanger of 17.8 days, in-house next-generation sequencing (NGS) of 12.5 days, and send-out NGS of 20.0 days. Standard testing had an average turnaround time of 11 days. Idylla average time to results was 4.9 days with a range of 0.4 to 13.5 days. CONCLUSIONS: The described cartridge-based system offers rapid and reliable testing of clinically actionable mutation in colorectal cancer specimens directly from formalin-fixed, paraffin-embedded tissue sections. Its simplicity and ease of use compared with other molecular techniques make it suitable for routine clinical laboratory testing.

Gene variant profiles and tumor metabolic activity as measured by FOXM1 expression and glucose uptake in lung adenocarcinoma.

BACKGROUND: Cancer cells displaying aberrant metabolism switch energy production from oxidative phosphorylation to glycolysis. Measure of glucose standardized uptake value (SUV) by positron emission tomography (PET), used for staging of adenocarcinoma in high-risk patients, can reflect cellular use of the glycolysis pathway. The transcription factor, FOXM1 plays a role in regulation of glycolytic genes. Cancer cell transformation is driven by mutations in tumor suppressor genes such as TP53 and STK11 and oncogenes such as KRAS and EGFR. In this study, SUV and FOXM1 gene expression were compared in the background of selected cancer gene mutations. METHODS: Archival tumor tissue from cases of lung adenocarcinoma were analyzed. SUV was collected from patient records. FOXM1 gene expression was assessed by quantitative reverse transcriptase polymerase chain reaction (qRT-PCR). Gene mutations were detected by allele-specific PCR and gene sequencing. RESULTS: SUV and FOXM1 gene expression patterns differed in the presence of single and coexisting gene mutations. Gene mutations affected SUV and FOXM1 differently. EGFR mutations were found in tumors with lower FOXM1 expression but did not affect SUV. Tumors with TP53 mutations had increased SUV (p = .029). FOXM1 expression was significantly higher in tumors with STK11 mutations alone (p < .001) and in combination with KRAS or TP53 mutations (p < .001 and p = .002, respectively). CONCLUSIONS: Cancer gene mutations may affect tumor metabolic activity. These observations support consideration of tumor cell metabolic state in the presence of gene mutations for optimal prognosis and treatment strategy.

Exceptional Response to Olaparib in a Patient With Recurrent Ovarian Cancer and an Entire BRCA1 Germline Gene Deletion.

PARP inhibitors are known to be effective in patients with ovarian cancer (OC) and germline mutations in BRCA1 and BRCA2 genes (BRCA mutations). Little is known, however, about any correlation between the deletion size and location of the BRCA mutation and the response to PARP inhibitors. Women with OC commonly undergo genetic testing because the presence of a germline BRCA mutation impacts therapeutic decisions and is important for cancer surveillance in patients and their family members. This report presents a case of a rare entire germline BRCA1 gene deletion and an exceptional response to a PARP inhibitor, olaparib, in a heavily pretreated patient with OC. Her disease course was also remarkable for complete responses to platinum-based chemotherapy and long chemotherapy-free intervals. Interestingly, the deletion of the entire BRCA1 gene was found after previously negative BRCA test results and is associated with a deletion of 6 adjacent genes without known clinical significance. She has remained progression-free and asymptomatic for >3 years on olaparib, with an overall survival of >12 years. We postulate that this unusually favorable response and prolonged overall survival is related to the cancer cells' inability to reverse the entire gene deletion to wild-type (a common mechanism of resistance to PARP inhibition). This case shows the value of genetic testing for patients with OC and highlights the utility of additional testing with previously negative results and limited genetic testing. It also provides insight into a potential mechanism of an exceptional response to PARP inhibition.

Somatic variants of potential clinical significance in the tumors of BRCA phenocopies.

BACKGROUND: BRCA phenocopies are individuals with the same phenotype (i.e. cancer consistent with Hereditary Breast and Ovarian Cancer syndrome = HBOC) as their affected relatives, but not the same genotype as assessed by blood germline testing (i.e. they do not carry a germline BRCA1 or BRCA2 mutation). There is some evidence of increased risk for HBOC-related cancers in relatives of germline variant carriers even though they themselves test negative for the familial variant (BRCA non-carriers). At this time, BRCA phenocopies are recommended to undergo the same cancer surveillance as individuals in the general population. This raises the question of whether the increased cancer risk in BRCA non-carriers is due to alterations (germline, somatic or epigenetic) in other cancer-associated genes which were not analyzed during BRCA analysis. METHODS: To assess the nature and potential clinical significance of somatic variants in BRCA phenocopy tumors, DNA from BRCA non-carrier tumor tissue was analyzed using next generation sequencing of 572 cancer genes. Tumor diagnoses of the 11 subjects included breast, ovarian, endometrial and primary peritoneal carcinoma. Variants were called using FreeBayes genetic variant detector. Variants were annotated for effect on protein sequence, predicted function, and frequency in different populations from the 1000 genomes project, and presence in variant databases COSMIC and ClinVar using Annovar. RESULTS: None of the familial BRCA1/2 mutations were found in the tumor samples tested. The most frequently occurring somatic gene variants were ROS1(6/11 cases) and NUP98 (5/11 cases). BRCA2 somatic variants were found in 2/6 BRCA1 phenocopies, but 0/5 BRCA2 phenocopies. Variants of uncertain significance were found in other DNA repair genes (ERCC1, ERCC3, ERCC4, FANCD2, PALB2), one mismatch repair gene (PMS2), a DNA demethylation enzyme (TET2), and two histone modifiers (EZH2, SUZ12). CONCLUSIONS: Although limited by a small sample size, these results support a role of selected somatic variants and epigenetic mechanisms in the development of tumors in BRCA phenocopies.

Misdiagnosis of Li-Fraumeni Syndrome in a Patient With Clonal Hematopoiesis and a Somatic TP53 Mutation.

Li-Fraumeni syndrome (LFS) is a rare genetic disorder that confers a high risk of developing certain malignancies at a young age. It is caused by germline mutations in the TP53 gene and is typically diagnosed by sequencing this gene in blood cells. The presence of a mutation in approximately half of the DNA reads (allelic fraction of 50%) is an indicator of a germline mutation, such as that in LFS. Clonal hematopoiesis (CH) is an expansion of a hematopoietic clone containing a somatic driver mutation with a low allelic fraction, usually not more than 10% to 20%. This report presents a patient with fallopian tube carcinoma who underwent multigene panel testing for cancer predisposition and was found to have a mutation in the TP53 gene, c.733G>T (p.Gly245Cys). Since the TP53 mutation had an allelic fraction of approximately 50%, it was interpreted as being germline, and the patient was diagnosed as having LFS. A year later, she developed acute myelogenous leukemia. Subsequent mutational analysis showed that the TP53 mutation was absent in her benign tissue sample but present in leukemic cells. Furthermore, sequencing of the fallopian tube tumor tissue revealed a different TP53 gene mutation, c.818G>T (p.Arg273Leu). These observations confirmed that the previously identified mutation in her blood was somatic rather than germline and that she had CH at the time of genetic testing. CH can occasionally lead to a misdiagnosis of a germline mutation and a cancer predisposition syndrome that has significant implications for patients and their families. Therefore, the abnormal result of genetic testing for hereditary cancer susceptibility should be carefully interpreted when the clinical presentation is atypical, when the patient is older, when the gene in question is known to have potential germline and somatic mutations such as the TP53 gene, and when the allelic fraction is approximately 50%.

Can chimerism explain breast/ovarian cancers in BRCA non-carriers from BRCA-positive families?

Hereditary breast and ovarian cancer syndrome (HBOC) is most frequently caused by mutations in BRCA1 or BRCA2 (in short, BRCA) genes. The incidence of hereditary breast and ovarian cancer in relatives of BRCA mutation carriers who test negative for the familial mutation (non-carriers) may be increased. However, the data is controversial, and at this time, these individuals are recommended the same cancer surveillance as general population. One possible explanation for BRCA phenocopies (close relatives of BRCA carriers who have developed cancer consistent with HBOC but tested negative for a familial mutation) is natural chimerism where lack of detectable mutation in blood may not rule out the presence of the mutation in the other tissues. To test this hypothesis, archival tumor tissue from eleven BRCA phenocopies was investigated. DNA from the tumor tissue was analyzed using sequence-specific PCR, capillary electrophoresis, and pyrosequencing. The familial mutations were originally detected in the patients' first-degree relatives by commercial testing. The same testing detected no mutations in the blood of the patients under study. The test methods targeted only the known familial mutation in the tumor tissue. Tumor diagnoses included breast, ovarian, endometrial and primary peritoneal carcinoma. None of the familial mutations were found in the tumor samples tested. These results do not support, but do not completely exclude, the possibility of chimerism in these patients. Further studies with comprehensive sequence analysis in a larger patient group are warranted as a chimeric state would further refine the predictive value of genetic testing to include BRCA phenocopies.

Identification of fluorescence in situ hybridization assay markers for prediction of disease progression in prostate cancer patients on active surveillance.

BACKGROUND: Prostate Cancer (PCa) is the second most prevalent cancer among U.S. males. In recent decades many men with low risk PCa have been over diagnosed and over treated. Given significant co-morbidities associated with definitive treatments, maximizing patient quality of life while recognizing early signs of aggressive disease is essential. There remains a need to better stratify newly diagnosed men according to the risk of disease progression, identifying, with high sensitivity and specificity, candidates for active surveillance versus intervention therapy. The objective of this study was to select fluorescence in situ hybridization (FISH) panels that differentiate non-progressive from progressive disease in patients with low and intermediate risk PCa. METHODS: We performed a retrospective case-control study to evaluate FISH biomarkers on specimens from PCa patients with clinically localised disease (T1c-T2c) enrolled in Watchful waiting (WW)/Active Surveillance (AS). The patients were classified into cases (progressed to clinical intervention within 10 years), and controls (did not progress in 10 years). Receiver Operating Characteristic (ROC) curve analysis was performed to identify the best 3-5 probe combinations. FISH parameters were then combined with the clinical parameters ─ National Comprehensive Cancer Network (NNCN) risk categories ─ in the logistic regression model. RESULTS: Seven combinations of FISH parameters with the highest sensitivity and specificity for discriminating cases from controls were selected based on the ROC curve analysis. In the logistic regression model, these combinations contributed significantly to the prediction of PCa outcome. The combination of NCCN risk categories and FISH was additive to the clinical parameters or FISH alone in the final model, with odds ratios of 5.1 to 7.0 for the likelihood of the FISH-positive patients in the intended population to develop disease progression, as compared to the FISH-negative group. CONCLUSIONS: Combinations of FISH parameters discriminating progressive from non-progressive PCa were selected based on ROC curve analysis. The combination of clinical parameters and FISH outperformed clinical parameters alone, and was complimentary to clinical parameters in the final model, demonstrating potential utility of multi-colour FISH panels as an auxiliary tool for PCa risk stratification. Further studies with larger cohorts are planned to confirm these findings.

Ectopic Thyroid Tissue: Immunohistochemistry and Molecular Analysis.

Ectopic thyroid tissue is rare and controversial. Some experts consider it to always be metastatic thyroid carcinoma, whereas others consider it benign as long as it is restricted to few follicles without cytoarchitectural features of papillary thyroid carcinoma. Immunohistochemistry (IHC) and molecular studies have not yet been performed to further characterize this entity. We retrospectively searched our pathology files for all ectopic thyroid inclusions and reviewed clinicopathologic characteristics and concurrent thyroid pathologic findings. We identified 8 cases from 7 patients. Ectopic thyroid tissue was present in the following locations: neck soft tissue: 3, thymus: 2, neck lymph nodes: 2, perihilar soft tissue: 1. All patients had histologically benign thyroid specimens. BRAFV600E (VE1) IHC, HBME-1 IHC, galectin-3 IHC, BRAFV600E allele-specific polymerase chain reaction (PCR) and NRAS/KRAS pyrosequencing were performed. To assess the sensitivity and specificity of BRAFV600E IHC compared with PCR; we tested 13 cases of primary and metastatic papillary and follicular thyroid carcinomas. All the ectopic cases were HBME-1, galectin-3, BRAFV600E (IHC, PCR), and NRAS/KRAS mutation negative (specificity=100%). Compared with PCR, BRAF IHC had 89% sensitivity and 100% specificity. Lack of common carcinoma-associated mutations supports benign nature of this entity. BRAF, HBME-1, and galectin-3 IHC are accurate and helpful when not enough tissue is available for molecular studies. IHC and molecular studies are more helpful than morphology alone in identifying benign thyroid rests.

Erratum to: LINE-1 is preferentially hypomethylated within adenomatous polyps in the presence of synchronous colorectal cancer.

[This corrects the article DOI: 10.1186/s13148-017-0325-7.].

LINE-1 is preferentially hypomethylated within adenomatous polyps in the presence of synchronous colorectal cancer.

BACKGROUND: Conventional tubular adenomas are frequently detected in patients undergoing average risk screening colonoscopy and are over-represented in patients who will develop colorectal cancer (CRC). Whether features of adenomas could serve as predictors of synchronous CRC is not known. Here, we investigate whether global methylation markers, including LINE-1, differ within adenomas in patients with and without synchronous CRC. METHODS: Colorectal tubular/tubulovillous adenomatous polyps in the absence (P group, n = 45) and in the presence of synchronous CRC (PC group, n = 32) were identified. Global methylation and demethylation by ELISA for 5-methylcytosine (5-mC) and 5-hydroxymethyl cytosine (5-hmC), respectively, were assessed in polyps and adjacent normal non-neoplastic tissue. LINE-1 hypomethylation was assessed by pyrosequencing of bisulfite-converted DNA as well. RESULTS: Global methylation (5-mC) showed no differences in overall methylation status in the adenomatous polyps in the two groups (5-mC relative to control %, PC group 0.117; P group 0.161, p = 0.148). Global hydroxymethylation 5-hmC was also not significantly different in adenomatous polyps of the PC group than in those of the P group (0.0059 vs 0.0097, p = 0.681). Similarly, global 5-hmC was not different between normal tissues from patients without neoplasia in comparison to those from CRC patients (0.0461 ± 0.080 vs 0.039 ± 0.159, p = 0.215). In contrast, adenomatous polyps of the PC group had lower levels of LINE-1 methylation compared to the adenomas in the P group (53.07 ± 4.5 vs 59.95 ± 5.4, p < 0.001). LINE-1 methylation was also significantly lower in the normal tissue from cancer patients compared to that from patients without any neoplasia (58.07 ± 3.78 vs 71.50 ± 6.47, p < 0.001). CONCLUSIONS: LINE-1 hypomethylation of precancerous adenomas correlates with the presence of synchronous CRC. Measurement of DNA hypomethylation levels of colorectal adenomas by LINE-1 could have future implications in approaches to defining CRC risk in screening programs.

Epidermal growth factor receptor (EGFR) mutations are exceptionally rare in thyroid transcription factor (TTF-1)-negative adenocarcinomas of the lung.

INTRODUCTION: Approximately 70% of lung adenocarcinomas express TTF-1. EGFR mutations are present in 13-15% of Western adenocarcinoma patients. This paper investigates TTF1 as a negative predictor of mutant EGFR in lung adenocarcinomas. RESULTS: In the pilot cohort (N = 301) two of 224 specimens positive for EGFR mutations had negative TTF-1 expression (sensitivity 99.1%, 95% confidence interval (CI) 96.8-99.9%). Estimated negative predictive values (NPV) for EGFR mutation prevalence rates of 13% and 15% are 99.5% (95% credible interval (CRI) 98.6%-99.9%) and 99.4% (CRI - 98.4%-99.9%). For EGFR mutation rates of 13% and 15%, using validation cohort data (211 patients), the estimated NPVs were 97% (95% CRI 92%-99%) and 96% (95% CRI 91%-99%). METHODS: Formalin-fixed paraffin-embedded tumors from lung adenocarcinoma patients were analyzed for EGFR mutations by allele-specific PCR in the 'pilot cohort'. TTF-1 status was documented as positive or negative. Negative predictive value (NPV) for a range of true prevalence of EGFR mutation (1%-50%) was estimated using Bayesian modeling. The hypothesis was validated in a separate 'validation' cohort using the same modeling. CONCLUSION: An overwhelming majority of TTF-1 negative adenocarcinomas will be negative for EGFR mutations. This finding allows for earlier initiation of chemotherapy in newly diagnosed TTF-1 negative adenocarcinomas of the lung with stage IV disease.

Use of cervical mucus to screen for gynecological malignancies: a pilot study.

High-grade malignancies are the leading cause of death from gynecological tumors. Unfortunately, no efficient screening method is available for these tumors. In this paper we report the results of a pilot study based on the frequency of TP53 mutations in these cancers. Mucus from the cervix of 32 hysterectomy specimens with no grossly visible cervical or serosal involvement were included in this study. TP53 exons 5-9 mutations were screened for mutations using single strand conformation polymorphism (SSCP). Immunostain for p53 protein was performed in all fallopian tubes and in a sample from the tumors that were identified prospectively. A total of 32 cases including 19 malignant, and 13 benign cases were included. P53 immunostain was positive in only 5 cases including 3 high grade malignant tumors and 2 precancerous lesions (serous tubal intraepithelial lesion or p53 signature) in the fallopian tubes. A TP53 mutation band pattern was detected by SSCP in 2/3 and 2/2 cases respectively. Twenty-seven cases were negative for p53 imunostain, 4 of which were positive for TP53 mutation by SSCP including 3 low-grade malignancies. The results of this study provide evidence that DNA from precursor lesions of high grade ovarian, fallopian tube and endometrial carcinomas can be detected in cervical mucus. Further studies using different markers, in preoperative setting and large scale screening studies will determine the utility of using cervical mucus to screen for gynecological malignancies.