Endoscopic and histopathologic reflux-associated mucosal damage in the remnant esophagus following transthoracic esophagectomy for cancer-5-year long-term follow-up.

Gastroesophageal reflux is a common problem following esophagectomy and reconstruction with gastric interposition. Despite a routine prescription of proton pump inhibitors, reflux-associated mucosal damage in the remnant esophagus is frequently observed. Purpose of this study is to evaluate mucosal damage in the esophageal remnant during long-term follow-up and to compare the prevalence of this damage between the subgroups of esophageal squamous cell and adenocarcinoma. All patients undergoing transthoracic Ivor-Lewis esophagectomy were prospectively entered in our IRB approved database. All patients underwent a routine check-up program with yearly surveillance endoscopies following esophagectomy. Only patients with a complete follow-up were included into this study. Endoscopic and histopathologic mucosal changes of the remnant esophagus were analyzed in close intervals. A total of 50 patients met the inclusion criteria, consisting of 31 adenocarcinomas (AC) and 19 squamous cell carcinomas (SCC). Mucosal damage was already seen 1 year after surgery in 20 patients macroscopically (43%) and in 21 patients microscopically (45%). At 5-year follow-up the prevalence for macroscopic and microscopic damage was 55% and 60%, respectively. The prevalence of mucosal damage was higher in AC patients than in SCC patients (1y-FU: 51% [AC] vs. 28% [SCC]; 5y-FU: 68% [AC] vs. 35% [SCC], P < 0.05). Newly acquired Barrett's esophagus was seen in 10 patients (20%) with two of those patients (20%) showing histopathologic proof of neoplasia. This study shows a high prevalence of reflux-associated mucosal damage in the remnant esophagus one year out of surgery and only a moderate increase in prevalence in the following years. Mucosal damage was more frequently seen in AC patients and the occurrence of de-novo Barrett's esophagus and de-novo neoplasia was high. Endoscopic surveillance with targeted biopsies seems to be an indispensable tool to follow patients after esophagectomy appropriately.

Simultaneous laryngopharyngeal pH monitoring (Restech) and conventional esophageal pH monitoring-correlation using a large patient cohort of more than 100 patients with suspected gastroesophageal reflux disease.

24-hour esophageal pH-metry is not designed to detect laryngopharyngeal reflux (LPR). The new laryngopharyngeal pH-monitoring system (Restech) may detect LPR better. There is no established correlation between these two techniques as only small case series exist. The aim of this study is to examine the correlation between the two techniques with a large patient cohort. All patients received a complete diagnostic workup for gastroesophageal reflux including symptom evaluation, endoscopy, 24-hour pH-metry, high resolution manometry, and Restech. Consecutive patients with suspected gastroesophageal reflux and disease-related extra-esophageal symptoms were evaluated using 24-hour laryngopharyngeal and concomitant esophageal pH-monitoring. Subsequently, the relationship between the two techniques was evaluated subdividing the different reflux scenarios into four groups. A total of 101 patients from December 2013 to February 2017 were included. All patients presented extra-esophageal symptoms such as cough, hoarseness, asthma symptoms, and globus sensation. Classical reflux symptoms such as heartburn (71%), regurgitation (60%), retrosternal pain (54%), and dysphagia (32%) were also present. Esophageal 24-hour pH-metry was positive in 66 patients (65%) with a mean DeMeester Score of 66.7 [15-292]. Four different reflux scenarios were detected (group A-D): in 39% of patients with abnormal esophageal pH-metry, Restech evaluation was normal (group A, n = 26, mean DeMeester-score = 57.9 [15-255], mean Ryan score = 2.6 [2-8]). In 23% of patients with normal pH-metry (n = 8, group B), Restech evaluation was abnormal (mean DeMeester-score 10.5 [5-13], mean Ryan score 63.5 [27-84]). The remaining groups C and D showed corresponding results. Restech evaluation was positive in 48% of cases in this highly selective patient cohort. As demonstrated by four reflux scenarios, esophageal pH-metry and Restech do not necessarily need to correspond. Especially in patients with borderline abnormal 24-hour pH-metry, Restech may help to support the decision for or against laparoscopic anti-reflux surgery.

Distinct gene expression profiles of proximal and distal colorectal cancer: implications for cytotoxic and targeted therapy.

Colorectal cancer (CRC) is a heterogeneous disease with genetic profiles and clinical outcomes dependent on the anatomic location of the primary tumor. How location has an impact on the molecular makeup of a tumor and how prognostic and predictive biomarkers differ between proximal versus distal colon cancers is not well established. We investigated the associations between tumor location, KRAS and BRAF mutation status, and the messenger RNA (mRNA) expression of proteins involved in major signaling pathways, including tumor growth (epidermal growth factor receptor (EGFR)), angiogenesis (vascular endothelial growth factor receptor 2 (VEGFR2)), DNA repair (excision repair cross complement group 1 (ERCC1)) and fluoropyrimidine metabolism (thymidylate synthase (TS)). Formalin-fixed paraffin-embedded tumor specimens from 431 advanced CRC patients were analyzed. The presence of seven different KRAS base substitutions and the BRAF V600E mutation was determined. ERCC1, TS, EGFR and VEGFR2 mRNA expression levels were detected by reverse transcriptase-PCR. BRAF mutations were significantly more common in the proximal colon (P<0.001), whereas KRAS mutations occurred at similar frequencies throughout the colorectum. Rectal cancers had significantly higher ERCC1 and VEGFR2 mRNA levels compared with distal and proximal colon tumors (P=0.001), and increased TS levels compared with distal colon cancers (P=0.02). Mutant KRAS status was associated with lower ERCC1, TS, EGFR and VEGFR2 gene expression in multivariate analysis. In a subgroup analysis, this association remained significant for all genes in the proximal colon and for VEGFR2 expression in rectal cancers. The mRNA expression patterns of predictive and prognostic biomarkers, as well as associations with KRAS and BRAF mutation status depend on primary tumor location. Prospective studies are warranted to confirm these findings and determine the underlying mechanisms.

Reversal of multidrug resistance by two novel indole derivatives.

Two new fused indoles were found to overcome multidrug resistance in P388/Adr cells in vitro. These agents potentiated the cytotoxicity of the antitumor drugs Adriamycin, vinblastine, and vincristine in multidrug-resistant cells with no effect on drug-sensitive parent P388 cells. They significantly increased the ATP-dependent accumulation of [3H]-vinblastine and inhibited efflux of the labeled drug from resistant cells. These compounds also inhibited photoaffinity labeling of P-glycoprotein by [3H]azidopine in P388/Adr cells and membranes isolated from these cells. In addition, the calcium antagonist activity of these compounds was very weak compared with that of verapamil. These data suggest that the compounds reported here may specifically overcome multidrug resistance without the serious hypotensive effects associated with calcium antagonists and that this activity may be independent of their ability to block calcium transport.

Prolactin as a chemoattractant for human breast carcinoma.

Prolactin (PRL) is recognized as a growth and differentiating hormone in the human breast. These effects are mediated by the PRL receptor (PRLr); when stimulated the PRL-PRLr complex activates several signaling cascades, including those involving the GTP-binding proteins Ras and Rac. The activation of these signaling pathways has been associated with cytoskeletal alterations and increased cellular motility. We hypothesized that such changes could occur in PRL-stimulated human breast cancer cells. To test this hypothesis, complementary studies, including wound closure, time-lapse video microscopy (TLVM), and Boyden chamber assay were performed. These studies revealed that PRL significantly enhanced the migration of the breast cancer cell lines T47D, MCF7, and MDA23 1. Co-stimulation with PRL was noted to potentiate epidermal growth factor (EGF)-induced cell motility. IF microscopy of filamentous actin using rhodamine-conjugated phalloidin revealed a significant and rapid generation of both membrane ruffling and stress fibers in response to PRL, an effect inhibited by the phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002. In sum, these data reveal that PRL stimulation modulates the cytoskeleton and induces the motility of human breast cancer cells in vitro, events that have been associated with the progression of mammary carcinoma in vivo. Given the recently delineated autocrine-paracrine role for PRL in human breast cancer, these findings could be of appreciable clinical significance.

17-beta Oestradiol Pretreatment of Mouse Striatal Neurons in Culture Enhances the Responses of Adenylate Cyclase Sensitive to Biogenic Amines.

Embryonic striatal neurons from the mouse grown in primary culture (6 day old culture) were used in order to investigate the effects of 17-beta oestradiol (17-beta E2) on biogenic amine-sensitive adenylate cyclases. Pretreatment (28 h) of intact cells with 17-beta E2 (10-9 M) enhanced cyclic AMP production induced by either dopamine, isoproterenol, serotonin, or 2-chloro-adenosine (maximal effective concentrations). These effects of 17-beta E2 on biogenic amine-sensitive adenylate cyclases occurred after several hours (8 h at least) and were seen in most cases with a concentration as low as 10-11 M (EC50: 10-10 M). They were additive with those induced by phenol red (5.6 microg/l) and chemically specific since 17alpha-oestradiol, 2(OH)17-beta E2, progesterone, and dexamethasone were without effect. In addition, they were not seen in cells which had been pretreated (30 h) with cycloheximide or alpha-amanitin, suggesting an involvement of de novo protein synthesis. Since 17-beta E2 did not influence cyclic AMP production induced by either forskolin or manganese ions, the stimulatory effects of 17-beta E2 pretreatment on biogenic amine-sensitive adenylate cyclases were not linked to an increase in the amount of enzyme catalytic units. 17-beta E2 pretreatment enhanced twofold the number of beta-adrenergic receptors (as estimated by the specific binding of (125I)iodocyanopindolol) but did not, in contrast, affect either the number or the affinity of dopaminergic receptors (as estimated by (125I)SCH 23982 binding). Therefore, the enhancing effects of 17-beta E2 pretreatment on biogenic amine-sensitive adenylate cyclases could be related either to an increased number of coupled receptors or to modifications of the adenylate cyclase transducing system (occurring probably at the G-protein level) or to a combination of the two.

Reduced glucose metabolism enhances the glutamate-evoked release of arachidonic acid from striatal neurons.

Glucose deprivation potentiates the glutamate receptor-evoked release of arachidonic acid from cultured mouse striatal neurons. In this study we investigated whether this potentiation would be modified by the end-products of glycolysis. These enhanced responses were completely reversed by the addition of increasing concentrations of either lactate or pyruvate. This reversal was not due to increased osmolarity as substituting sucrose for lactate or pyruvate did not mimic their effects. In contrast, in the presence of glucose, neither lactate nor pyruvate was effective. Furthermore, these monocarboxylic acids rescued neuronal respiration in the absence of glucose. Inhibiting glycolysis with iodoacetate in the presence of glucose reproduced the potentiated glutamate-evoked release of arachidonic acid observed following glucose deprivation and reduced neuronal respiration to the same extent as that observed in the absence of glucose. All of these effects were overcome by the addition of either lactate or pyruvate. The reversal of the potentiated glutamate-evoked release of arachidonic acid by lactate or pyruvate was inhibited by a specific inhibitor of monocarboxylic acid transport, alpha-cyano-4-hydroxycinnamic acid, suggesting that lactate and pyruvate act intracellularly. Therefore, we propose that the enhanced release of arachidonic acid evoked by glutamate during glucose deprivation results from reduced glycolysis and hence from a depletion of lactate or pyruvate.

Primary intraepithelial sebaceous gland carcinoma of the palpebral conjunctiva.

Sebaceous gland carcinoma usually arises from meibomian or Zeis glands deep within the eyelid, but it can rarely arise within the conjunctival epithelium without a deep component. We describe a woman with a history of chronic blepharoconjunctivitis unresponsive to topical medications. Examination disclosed confluent papillary hypertrophy of the upper palpebral conjunctiva and deposits of white flaky material. Tarsoconjunctival punch biopsy revealed intraepithelial sebaceous gland carcinoma. Management consisted of frozen section-controlled complete tumor excision with removal of the entire posterior lamella of the right upper eyelid, cryotherapy to the margins, and reconstruction. Histopathologic analysis confirmed primary sebaceous gland carcinoma localized to the conjunctival epithelium without involvement of underlying meibomian or Zeis glands or the caruncle. Patients with unexplained chronic unilateral blepharoconjunctivitis or papillary hypertrophy of the palpebral conjunctiva should be considered for biopsy to rule out neoplasia, even when there is no sign of an underlying eyelid mass.

Nicotine protects cultured striatal neurones against N-methyl-D-aspartate receptor-mediated neurotoxicity.

The role of cholinergic mechanisms in N-methyl-D-aspartate (NMDA)-mediated neuronal death was investigated using mouse striatal neurones in primary culture. A 30 min exposure of striatal neurones to increasing concentrations of NMDA resulted 24 h later in dramatic neuronal degeneration as assessed by MTT staining, crystal violet incorporation and determination of microtubule-associated protein 2. The NMDA-induced neurodegeneration was strongly inhibited by the co-application of two non-selective cholinergic agonists, acetylcholine or carbachol. This protective effect appears to be mediated by nicotinic receptors since it was insensitive to the muscarinic antagonist atropine but mimicked by nicotine, nornicotine and 1,1-dimethyl-4-phenyl-piperazinium. Moreover, the nicotine-evoked neuroprotection was inhibited by the central nicotinic antagonist hexamethonium. Therefore, this study suggests that cholinergic interneurones play an important role in neuronal survival in the striatum.

Balloon catheter dilation for treatment of adults with partial nasolacrimal duct obstruction: a preliminary report.

PURPOSE: The purpose of this study is to determine the efficacy and morbidity of balloon catheter dilation for treatment of partial acquired nasolacrimal duct obstruction in adults with epiphora. METHODS: We performed balloon dacryocystoplasty prospectively on a series of 15 partial nasolacrimal duct obstructions in 13 adults with epiphora. Partial obstruction was diagnosed by a negative Jones-1 test and canalicular irrigation revealing simultaneous reflux through the opposing punctum and drainage into the nose. Balloon dacryocystoplasty was performed under local anesthesia using an antegrade insertion technique. Silicone intubation of the nasolacrimal system was performed immediately after balloon catheter dilation, and the tubes were removed 2 months postoperatively. RESULTS: Success was measured objectively and subjectively at follow-up examinations 2 months and 6 months after the procedure. At 2 months, 11 (73%) of 15 obstructions were open on irrigation, with subjective success (Munk, grade 0 or grade 1) reported in 13 (87%) of 15 obstructions. At 6 months, 11 (73%) of 15 obstructions were open on irrigation, with subjective success (Munk, grade 0 or grade 1) reported in 9 (60%) of 15 obstructions. CONCLUSIONS: Balloon dacryocystoplasty may be a satisfactory primary treatment for adults with acquired partial nasolacrimal duct obstruction who exhibit no clinical signs of chronic infection. Additional long-term observations following balloon dacryocystoplasty are required.

Image-guided transorbital roof craniotomy via a suprabrow approach: a surgical series of 72 patients.

OBJECTIVE: Many subfrontal and orbitofrontal craniotomy techniques have been developed. We present our results with the transorbital roof craniotomy, a frontal craniotomy that incorporates the orbital roof and is performed via a suprabrow incision. This technique was used in 72 patients, primarily for tumor resection. METHODS: Charts were retrospectively reviewed for all patients undergoing transorbital procedures. A total of 72 patients underwent 82 transorbital craniotomies from September 1995 to July 1999. The primary indication for the transorbital approach was mass lesion of the orbit, anterior fossa, or parasellar region. RESULTS: A total of 47 women and 25 men with a mean age of 53 years underwent 82 procedures. The primary pathological finding was meningioma, which occurred in 40 patients (55.6%), followed by craniopharyngioma (6.9%), pituitary macroadenoma (6.9%), schwannoma (5.5%), and hemangioma (5.5%). Simpson Grade I or II resection was achieved in 54% of patients, with Simpson Grade III to V resection achieved in the remaining 46%. Forty-one patients presented with visual loss in 43 cases, with 44.2% experiencing postoperative visual improvement, 46.5% remaining unchanged, and 9.3% worsening. Overall morbidity was 18.4%, with cerebrospinal fluid leak being the most common complication (6.6%). No patients died. CONCLUSION: The transorbital roof craniotomy is an evolutionary approach that provides excellent exposure to the orbit, anterior fossa, and parasellar region with little significant morbidity and, in our series, no mortality. Although we have used this approach primarily for resection of mass lesions, future directions for this procedure will likely lie in treating vascular lesions and lesions of the interpeduncular fossa.

Tarsorrhaphy: clinical experience from a cornea practice.

PURPOSE: To evaluate indications, success rate, and complications of tarsorrhaphy in a cohort of cornea and external disease patients. METHODS: In this study, charts of patients who underwent tarsorrhaphies from January 1, 1995, to September 30, 2000, were retrospectively evaluated. Information reviewed included patient age and sex, indication for tarsorrhaphy, duration of signs and symptoms before tarsorrhaphy, time to epithelial healing after tarsorrhaphy, type of tarsorrhaphy (temporary/permanent), complications, timing of tarsorrhaphy removal, recurrence of signs and symptoms after complete or partial opening of the tarsorrhaphy, number of tarsorrhaphies needed to be replaced or extended, and duration of follow up. RESULTS: Seventy-seven patients were included in this study. Indications for a tarsorrhaphy were persistent epithelial defects or other ocular surface problems associated with neurotrophic ulcers, penetrating keratoplasty (PK), postinfection, exposure keratopathy, surgery other than PK, dry eye syndrome, radiation keratopathy, ocular cicatricial pemphigoid, Stevens-Johnson syndrome, entropion, and application of tissue adhesive. The epithelial defects in 70 (90.9%) of the 77 eyes completely resolved. Overall, the mean duration of signs and symptoms before tarsorrhaphy was 89.8 +/- 27.8 days, and time-to-healing after tarsorrhaphy was 18.0 +/- 2.0 days. The difference between the duration of the signs and symptoms before tarsorrhaphy and time-to-healing after tarsorrhaphy was statistically significant ( p = 0.01). Of the 77 tarsorrhaphies, 24 (31.2%) were temporary and 53 (68.8%) were permanent. Complications after tarsorrhaphy included trichiasis, adhesion between upper and lower lids after tarsorrhaphy lysis, premature opening of the temporary tarsorrhaphy, pyogenic granuloma, and keloid formation of the eyelid. CONCLUSION: Tarsorrhaphy is a very effective and safe procedure in the management of nonhealing epithelial defects and other surface problems, with a 90.9% success rate and only minor complications.

Botulinum toxin therapy.

Botulinum toxin therapy has emerged as a treatment modality for a variety of spastic- or contracture-related muscle diseases. Its safety has been proven for long-term use in the treatment of benign essential blepharospasm, hemifacial spasm, and certain types of strabismus. Recent approval from the Federal Drug Administration should make botulinum toxin available for use in a greater number of patients.

Phenelfamycins, a novel complex of elfamycin-type antibiotics. I. Discovery, taxonomy and fermentation.

Phenelfamycins A, B, C, E, F and unphenelfamycin have been discovered in the fermentation broth of two soil isolates, designated AB 999F-80 and AB 1047T-33. These isolates were identified as strains of Streptomyces violaceoniger. The antibiotics were selected for their activity against anaerobic bacteria.

Dunaimycins, a new complex of spiroketal 24-membered macrolides with immunosuppressive activity. I. Taxonomy of the producing organisms, fermentation and antimicrobial activity.

The dunaimycins are a new complex of spiroketal 24-membered macrolides discovered in the fermentation broth of two actinomycetes. Based on taxonomic studies these two cultures, which were isolated from soil, were identified as Streptomyces diastatochromogenes strains AB 1691Q-321 and AB 1711J-452. The dunaimycins possess both immunosuppressive and antimicrobial activity.

Arizonins, a new complex of antibiotics related to kalafungin. I. Taxonomy of the producing culture, fermentation and biological activity.

The arizonins, a novel complex of antibiotics related to kalafungin, were discovered in the fermentation broth of Actinoplanes sp. AB660D-122. Comparative taxonomic studies indicated that the culture is a new species and therefore has been designated Actinoplanes arizonaensis sp. nov. Two members of the complex, arizonins A1 and B1, exhibit moderate to potent in vitro antimicrobial activity against pathogenic strains of Gram-positive bacteria.

Pacidamycins, a novel series of antibiotics with anti-Pseudomonas aeruginosa activity. I. Taxonomy of the producing organism and fermentation.

The pacidamycins are a new complex of nucleosidyl-peptide antibiotics with highly specific activity against Pseudomonas aeruginosa. They are produced by Streptomyces coeruleorubidus AB 1183F-64 which was isolated from a soil sample collected at Offenburg in the FRG. The mature spore masses of the producing organism are greenish gray to blue, and the spore chains are arranged in spirals. After the structures of the pacidamycins were determined, the fermentation medium was supplemented with component amino acids. This resulted in the directed biosynthesis of several members of the complex. The overall antibiotic recovered was increased from 1 approximately 2 mg/liter to more than 100 mg/liter through a combination of strain selection, medium manipulation and amino acid feeding experiments.

A new analysis method of single molecule fluorescence using series of photon arrival times: theory and experiment.

Up to now, single molecule fluorescence experiments were performed by dividing the time into a set of intervals and to observe the number of fluorescence photons arriving in each interval. It is obvious that the detected photons carry less information than the arrival times of the photons themselves. From the arrival times, one can still calculate the number of photons in any user-defined interval; whereas, when only the number of photons in an interval are recorded, information about their positions in time is lost. Therefore, we present a new analysis method of single molecule fluorescence data based on the positions in time of the detected fluorescence photons. We derive mathematically different statistical characteristics describing the single molecule fluorescence experiment assuming an immobilized molecule. The theory of point processes using the generating functionals formalism is ideally suited for a consistent description, linking the statistical characteristics of the excitation and detected photons to the statistical characteristics of the single motionless molecule. We then use computer-generated data sets mimicking the single molecule fluorescence experiment to explore the parametric estimation of mono- and bi-exponential single molecule impulse response functions (SMIRFs) via the following statistical characteristics: the probability density distributions (pdd) of the single and first photocount time positions in a user-defined detection interval, the probability distribution of the number of photocounts per user-defined detection interval, the time correlation function and the pdd of the time interval between two consecutive photocounts. It is shown that all of the above characteristics ensure a satisfactory recovery of the decay time of mono-exponential SMIRFs for a broad range of excitation intensities and widths of user-defined detection intervals. For bi-exponential SMIRFs, the selection of the experimental conditions is more critical and dependent on the detection procedure. At lower excitation intensities it is advantageous to use the pdds of the single and first photocount time occurrences in the user-defined detection interval. To show the practical usefulness of the new analysis method, series of photon arrival times from immobilized single molecules of DiI and rhodamine 6G were analyzed to estimate triplet lifetimes and intersystem crossing yields.

Triplet states as non-radiative traps in multichromophoric entities: single molecule spectroscopy of an artificial and natural antenna system.

Energy transfer in antenna systems, ordered arrays of chromophores, is one of the key steps in the photosynthetic process. The photophysical processes taking place in such multichromophoric systems, even at the single molecule level, are complicated and not yet fully understood. Instead of directly studying individual antenna systems, we have chosen to focus first on systems for which the amount of chromophores and the interactions among the chromophores can be varied in a systematic way. Dendrimers with a controlled number of chromophores at the rim fulfill those requirements perfectly. A detailed photophysical study of a second-generation dendrimer, containing eight peryleneimide chromophores at the rim, was performed 'J. Am. Chem. Soc., 122 (2000) 9278'. One of the most intriguing findings was the presence of collective on/off jumps in the fluorescence intensity traces of the dendrimers. This phenomenon can be explained by assuming a simultaneous presence of both a radiative trap (energetically lowest chromophoric site) and a non-radiative trap (triplet state of one chromophore) within one individual dendrimer. It was shown that an analogue scheme could explain the collective on/off jumps in the fluorescence intensity traces of the photosynthetic pigment B-phycoerythrin (B-PE) (Porphyridium cruentum). The different values of the triplet lifetime that could be recovered for a fluorescence intensity trace of B-PE were correlated with different intensity levels in the trace, suggesting different chromophores acting as a trap as function of time.

KRAS mutations in non-small-cell lung cancer and colorectal cancer: implications for EGFR-targeted therapies.

BACKGROUND: KRAS mutations are associated with diverse biologic functions as well as prognostic and predictive impact in non-small cell-lung cancer (NSCLC) and colorectal cancer (CRC). In CRC, benefit from monoclonal antibody therapies targeting EGFR is generally limited to patients whose tumors have wild-type (WT) KRAS, whereas data suggest that this association is not present for NSCLC. We hypothesized that the unique tobacco-related carcinogenesis of NSCLC results in a divergence of KRAS MT genotype compared with CRC, contributing to differences in outcomes from EGFR-targeted therapies. MATERIAL AND METHODS: Tumor from 2603 patients (838 CRC and 1765 NSCLC) was analyzed for KRAS mutations. DNA was extracted from microdissected formalin-fixed-paraffin-embedded specimens (FFPE) and 7 different base substitutions in codons 12 and 13 of KRAS were determined. RESULTS: KRAS mutation genotype differed significantly between NSCLC and CRC in frequency (25% vs. 39%; p<0.001), smoking-associated G>T transversions (73% versus 27%; p<0.001), and ratio of transversions to transitions (3.5 vs. 0.79; p<0.001). In NSCLC GLY12Cys mutations, resulting from a codon 12 GGT>TGT substitution, were observed in 44% compared to 10% for CRC. In contrast, codon 12 or 13 GLY>ASP substitutions (resulting in a G>A transition) were more frequent in CRC (42%) compared with NSCLC (21%). CONCLUSION: In this large dataset, KRAS mutation patterns are quantitatively and qualitatively distinct between NSCLC and CRC, reflecting in part differences in tobacco-related carcinogenesis. In light of differences in predictive value for EGFR-directed monoclonal antibody therapy and prognosis for specific KRAS mutations between NSCLC and CRC, these data provide an underlying biologic rationale.