Impact of low-dose CT on lung cancer screening

Utilization of Diagnostic Procedures After Lung Cancer Screening in the National Lung Screening Trial

OBJECTIVE

To examine utilization patterns of diagnostic procedures after lung cancer screening among participants enrolled in the National Lung Screening Trial.

METHODS

Using a sample of National Lung Screening Trial participants with abstracted medical records, we assessed utilization of imaging, invasive, and surgical procedures after lung cancer screening. Missing data were imputed using multiple imputation by chained equations. For each procedure type, we examined utilization within a year after the screening or until the next screen, whichever came first, across arms (low-dose CT [LDCT] versus chest X-ray [CXR]) and by screening results. We also explored factors associated with having these procedures using multivariable negative binomial regressions.

RESULTS

After baseline screening, our sample had 176.5 and 46.7 procedures per 100 person-years for those with a false-positive and negative result, respectively. Invasive and surgical procedures were relatively infrequent. Among those who screened positive, follow-up imaging and invasive procedures were 25% and 34% less frequent in those screened with LDCT, compared with CXR. Postscreening utilization of invasive and surgical procedures was 37% and 34% lower at the first incidence screen compared with baseline. Participants with positive results at baseline were six times more likely to undergo additional imaging than those with normal findings.

DISCUSSION

Use of imaging and invasive procedures to evaluate abnormal findings varied by screening modality, with a lower rate for LDCT than CXR. Invasive and surgical workup were less prevalent after subsequent screening examinations compared with baseline screening. Utilization was associated with older age but not gender, race or ethnicity, insurance status, or income.

Neoadjuvant immunotherapy for non-small cell lung cancer: State of the art

Lung cancer mortality has decreased over the past decade and can be partly attributed to advances in targeted therapy and immunotherapy. Immune checkpoint inhibitors (ICIs) have rapidly evolved from investigational drugs to standard of care for the treatment of metastatic non-small cell lung cancer (NSCLC). In particular, antibodies that block inhibitory immune checkpoints, such as programmed cell death protein 1 (PD-1) and programmed cell death 1 ligand 1 (PD-L1), have revolutionized the treatment of advanced NSCLC, when administered alone or in combination with chemotherapy. Immunotherapy is associated with higher response rates, improved overall survival (OS), and increased tolerability compared with conventional cytotoxic chemotherapy. These benefits may increase the utility of immunotherapy and its combinational use with chemotherapy in the neoadjuvant treatment of patients with NSCLC. Early findings from various ongoing clinical trials suggest that neoadjuvant ICIs alone or combined with chemotherapy may significantly reduce systemic recurrence and improve long-term OS or cure rates in resectable NSCLC. Here we further summarize the safety and efficacy of various neoadjuvant treatment regimens including immunotherapy from ongoing clinical trials and elaborate the role of neoadjuvant immunotherapy in patients with resectable NSCLC. In addition, we discuss several unresolved challenges, including the evaluations to assess neoadjuvant immunotherapy response, the role of adjuvant treatment after neoadjuvant immunotherapy, the efficacy of treatment for oncogenic-addicted tumors, and predictive biomarkers. We also provide our perspective on ways to overcome current obstacles and establish neoadjuvant immunotherapy as a standard of care.

Optimization of a calibration phantom for quantitative radiography

OBJECTIVE

Dual energy radiography (DER) makes it possible to obtain separate images for soft-tissue and bony structures (tissue maps) based on the acquisition of two radiographs at different source peak-kilovoltage values. Current DER studies are based on the weighted subtraction method, which requires either manual tuning or the use of precomputed tables, or on decomposition methods, which make use of a calibration to model soft-tissue and bone components. In this study, we examined in depth the optimum method to perform this calibration.

METHODS

We used simulations to optimize the calibration protocol and evaluated the effect of the material and size of a calibration phantom composed of two wedges and its positioning in the system. Evaluated materials were water, PMMA and A-150 as soft-tissue equivalent, and Teflon, B-100 and aluminum as bone equivalent, with sizes from 5 to 30 cm. Each material combination was compared with an ideal phantom composed of soft tissue and bone. Our simulation results enabled us to propose four designs that were tested with the NOVA FA X-ray system with a realistic thorax phantom.

RESULTS

Calibration based on a very simple and inexpensive phantom with no strict requirements in its placement results in appropriate separation of the spine (a common focus in densitometry studies) and the identification of nodules as small as 6 mm, which have been reported to have a low rate of detection in radiography.

CONCLUSION

The proposed method is completely automatic, avoiding the need for a radiology technician with expert knowledge of the protocol, as is the case in densitometry exams. The method provides real mass thickness values, enabling quantitative planar studies instead of relative comparisons.

CYFRA 21-1 in patients with suspected cancer: evaluation of an optimal cutoff to assess the diagnostic efficacy and prognostic value

Objectives

Chosen cutoff for cytokeratin 19 fragment antigen (CYFRA 21-1) as a tumor biomarker considerably influences its diagnostic and prognostic usefulness. The aim of the present study is to determine an optimal cutoff value for diagnostic validity of CYFRA 21-1 by Lumipulse ^® technology in patients with suspected cancer and also to determine if CYFRA 21-1 levels provide prognostic value.

Methods

A consecutive 284 patients suggestive of malignant disease from six hospitals of Madrid were enrolled in a retrospective design. Optimal CYFRA 21-1 cutoff value was obtained by receiver operating characteristic curve and Youden test. The diagnostic validity was evaluated according to sensitivity, specificity, predictive values and likelihood ratios. The prognostic value of CYFRA 21-1 was checked using multiple logistic regression. Thirty-two diagnostic cancers were confirmed.

Results

The most optimal cutoff was 3.15 ng/mL. This cutoff showed a better specificity 93.63% (95% confidence interval [CI], 89.66-96.16), positive predictive value 60.98% (95% CI, 44.54-75.38) and positive likelihood ratio 12.65 (95% CI, 7.64-20.95) than the cutoff recommended by Fujirebio^® (1.8 ng/mL) (specificity: 73.71% [95% CI, 67.72-78.95], positive predictive value: 29.79% [95% CI, 21.02-40.23] and positive likelihood ratio 3.43 [95% CI, 2.71-4.35]), improving the current diagnostic accuracy. In multivariate analysis, elevated levels of CYFRA 21-1 (>3.15 ng/mL) was confirmed as an unfavorable prognostic factor.

Conclusions

The best cutoff for CYFRA 21-1 obtained was 3.15 ng/mL in patients with suspected cancer. This new cutoff decreases the false positive rate and improves the diagnostic efficacy of CYFRA 21-1 as a tumor marker as well as its association with death events.

Surgical Outcomes in a Large, Clinical, Low-Dose Computed Tomographic Lung Cancer Screening Program

BACKGROUND

Lung cancer screening with low-dose computed tomography is proven to reduce lung cancer mortality among high-risk patients. However, critics raise concern over the potential for unnecessary surgical procedures performed for benign disease as a result of screening. We reviewed our outcomes in a large clinical lung cancer screening program to assess the number of surgical procedures done for benign disease, as we believe this is an important quality metric.

METHODS

We retrospectively reviewed our surgical outcomes of consecutive patients who underwent low-dose computed tomography lung cancer screening from January 2012 through June 2014 using a prospectively collected database. All patients met the National Comprehensive Cancer Network lung cancer screening guidelines high-risk criteria.

RESULTS

There were 1,654 screened patients during the study interval with clinical follow-up at Lahey Hospital & Medical Center. Twenty-five of the 1,654 (1.5%) had surgery. Five of 25 had non-lung cancer diagnoses: 2 hamartomas, 2 necrotizing granulomas, and 1 breast cancer metastasis. The incidence of surgery for non-lung cancer diagnosis was 0.30% (5 of 1,654), and the incidence of surgery for benign disease was 0.24% (4 of 1,654). Twenty of 25 had lung cancer, 18 early stage and 2 late stage. There were no surgery-related deaths, and there was 1 major surgical complication (4%) at 30 days.

CONCLUSIONS

The incidence of surgical intervention for non-lung cancer diagnosis was low (0.30%) and is comparable to the rate reported in the National Lung Screening Trial (0.62%). Surgical intervention for benign disease was rare (0.24%) in our experience.

Prevalence of benign pulmonary lesions excised for suspicion of malignancy: could it reflect a quality management index of indeterminate lung lesions?

Background

The effort to detect lung cancer in ever-earlier stages leads to the identification of an increasing number of patients without preoperative histological diagnosis. The aim of this study is to determine the prevalence and characteristics of benign lesions excised in the context of lung cancer surgery.

Methods

We retrospectively analyzed data from 125 surgical procedures. We compared the preoperative clinical or cyto-histological diagnosis with the surgical-pathologic diagnosis in order to identify the percentage of benign lesions excised. Furthermore, other parameters were analyzed, such as age, sex, tumor size, the presence of calcification, and the type of surgery according to subgroup.

Results

Of the 125 patients included in the study, 63 (50.4%) had a preoperative histological diagnosis of malignancy, corresponding to 56 cases (44.8%) of primary lung cancer and 7 cases (5.6%) of metastases. The 62 (49.6%) remaining cases without preoperative histological diagnosis were divided among 50 (40%) solitary pulmonary nodules and 12 (9.6%) pulmonary masses. According to the postoperative pathologic examination, we identified 12 (9.6%) benign lesions excised during lung cancer surgery. There were no statistically significant differences by subgroups with respect to age or sex. We found statistically significant evidence regarding the size and wedge resection as the surgical technique of choice for this type of benign lesion.

Conclusion

Our study obtained results similar to those published by other groups regarding the resection of benign lesions in lung cancer surgery. This percentage could be a quality management index of indeterminate lung lesions.

The assessment of the role of baseline low-dose CT scan in patients at high risk of lung cancer

BACKGROUND

Despite the progress in contemporary medicine comprising diagnostic and therapeutic methods, lung cancer is still one of the biggest health concerns in many countries of the world. The main purpose of the study was to evaluate the detection rate of pulmonary nodules and lung cancer in the initial, helical low-dose CT of the chest as well as the analysis of the relationship between the size and the histopathological character of the detected nodules.

MATERIAL/METHODS

We retrospectively evaluated 1999 initial, consecutive results of the CT examinations performed within the framework of early lung cancer detection program initiated in Szczecin. The project enrolled persons of both sexes, aged 55-65 years, with at least 20 pack-years of cigarette smoking or current smokers. The analysis included assessment of the number of positive results and the evaluation of the detected nodules in relationship to their size. All of the nodules were classified into I of VI groups and subsequently compared with histopathological type of the neoplastic and nonneoplastic pulmonary lesions.

RESULTS

Pulmonary nodules were detected in 921 (46%) subjects. What is more, malignant lesions as well as lung cancer were significantly, more frequently discovered in the group of asymptomatic nodules of the largest dimension exceeding 15 mm.

CONCLUSIONS

The initial, low-dose helical CT of the lungs performed in high risk individuals enables detection of appreciable number of indeterminate pulmonary nodules. In most of the asymptomatic patients with histopathologically proven pulmonary nodules greater than 15 mm, the mentioned lesions are malignant, what warrants further, intensified diagnostics.

Sensitivity enhancement in the determination of volatile biomarkers in saliva using a mass spectrometry-based electronic nose with a programmed temperature vaporizer

With a view to improving the sensitivity of direct coupling of a headspace sampler (HS) with a mass spectrometer (MS), here we propose the use of a programmed temperature vaporizer (PTV) in solvent-vent injection mode before the sample is introduced into the MS. This preconcentration scheme has been used for some time in many methods based on gas chromatography (GC), but to the best of our knowledge it has not yet been used in an electronic nose based on MS. The increase in the S/N ratio with the proposed instrumental configuration (HS-PTV/MS) lies between 6.9- and 22-fold. The main advantage of using this injector lies in the fact that it does not involve time-consuming steps. To check the possibilities of this methodology, saliva samples from healthy volunteers and patients with different types of illnesses (including some types of cancer) were analyzed. None of the compounds studied was detected in the samples corresponding to the healthy volunteers. One or more biomarkers, at levels ranging from 13 to 500 μg/L, were found in five of the samples from the patients. Additionally, separative analysis by HS-PTV-GC/MS was performed for confirmatory purposes and both methods provided similar results. The main advantage of the proposed methodology is that no prior chromatographic separation and no sample manipulation are required.

Evaluation of undiagnosed solitary lung nodules according to the probability of malignancy in the American College of Chest Physicians (ACCP) evidence-based clinical practice guidelines

Background

This study retrospectively investigated the clinical significance of undiagnosed solitary lung nodules removed by surgical resection.

Patients and methods

We retrospectively collected data on the age, smoking, cancer history, nodule size, location and spiculation of 241 patients who had nodules measuring 7 mm to 30 mm and a final diagnosis established by histopathology. We compared the final diagnosis of each patient with the probability of malignancy (POM) which was proposed by the American College of Chest Physicians (ACCP) guidelines.

Results

Of the 241 patients, 203 patients were diagnosed to have a malignant lung tumor, while 38 patients were diagnosed with benign disease. There were significant differences in the patients with malignant and benign disease in terms of their age, smoking history, nodule size and spiculation. The mean value and the standard deviation of the POM in patients with malignant tumors were 51.7 + 26.1%, and that of patients with benign lesions was 34.6 + 26.7%. The area under the receiver operating characteristic (ROC) curve (AUC) was 0.67. The best cut-off value provided from the ROC curve was 22.6. When the cut-off value was set at 22.6, the sensitivity was 83%, specificity 52%, positive predictive value 90%, negative predictive value 36% and accuracy 77%, respectively.

Conclusions

The clinical prediction model proposed in the ACCP guidelines showed unsatisfactory results in terms of the differential diagnosis between malignant disease and benign disease of solitary lung nodules in our study, because the specificity, negative predictive value and AUC were relatively low.

Circulating microRNAs: next-generation biomarkers for early lung cancer detection

Early diagnosis of lung cancer by low-dose computed tomography is an effective strategy to reduce cancer mortality in high-risk individuals. However, recruitment of at-risk individuals with asymptomatic lung cancer still remains challenging. We developed a minimal invasive serum test, based on the detection of circulating microRNAs, which can identify at-risk individuals with asymptomatic early stage non-small cell lung carcinomas with 80% accuracy.

Screening and early detection of lung cancer

Lung cancer with an estimated 342,000 deaths in 2008 (20% of total) is the most common cause of death from cancer, followed by colorectal cancer (12%), breast cancer (8%), and stomach cancer (7%) in Europe. In former smokers, the absolute lung cancer risk remains higher than in never-smokers; these data therefore call for effective secondary preventive measures for lung cancer in addition to smoking cessation programs. This review presents and discusses the most recent advances in the early detection and screening of lung cancer.An overview of randomized controlled computerized tomography-screening trials is given, and the role of bronchoscopy and new techniques is discussed. Finally, the approach of (noninvasive) biomarker testing in the blood, exhaled breath, sputum, and bronchoscopic specimen is reviewed.

Smoking behavior 1 year after computed tomography screening for lung cancer: Effect of physician referral for abnormal CT findings

BACKGROUND

Computed tomography (CT) lung cancer screening offers a unique clinical setting in which to promote smoking cessation. Focusing on outcomes related to the reporting of CT abnormality, we examined the natural history of smoking in the Pittsburgh Lung Screening Study.

METHODS

Pittsburgh Lung Screening Study recruited 50- to 79-year-old current and former cigarette smokers living in the Pittsburgh area. We examined self-reported smoking outcomes 1 year after study entry in a subgroup that contained 2,094 active cigarette smokers without interval lung cancer diagnosis (50.7% women; median age, 57 years; 40-year median duration of cigarette smoking; and 65.2% > or =20 cigarettes/d). Analyses compared efforts to quit in relation to physician referral for abnormal CT.

RESULTS

Since study entry, 58.5% [95% confidence interval (95% CI), 56.3-60.6%] reported any quit attempt and 27.2% (95% CI, 25.3-29.1%) reported any quit interval >30 days. One year after study entry, 15.5% (95% CI, 14.0-17.1%) reported not smoking for >30 days. Comparing persons referred because of CT abnormalities creating moderate or high lung cancer suspicion (n = 156; 7.4%) to persons not referred for any reason (n = 1145; 54.7%), propensity score-adjusted fractions with any quit attempt and with any quit interval >30 days increased 18.8% (95% CI, 11.1-26.5%) and 17.7% (95% CI, 9.4-26.0%), respectively. The fraction quit >30 days at 1 year increased 12.2% (95% CI, 4.9-19.5%).

CONCLUSIONS

Persons who experienced referral because of abnormal CT reported more smoking cessation.

Premalignant and malignant cells in sputum from lung cancer patients

BACKGROUND

The objective of this study was to assess the frequency of premalignant and malignant cells in sputum from patients with lung cancer and to measure the dependence of these cells on cancer stage, histologic type, tumor size, and tumor location.

METHODS

This analysis included 444 patients with lung cancer. First, all patients were asked to produce sputum spontaneously; then, they underwent sputum induction. Slide preparations of the sputa were screened for the presence of abnormal cells.

RESULTS

Of all patients with lung cancer who had produced adequate specimens, 74.6% had sputum that was positive for premalignant or worse cells, whereas 48.7% had sputum that was positive for malignant cells alone. Surprisingly, the presence of premalignant or worse cells in sputum depended only moderately on disease stage (82.9% of stage IV cancers vs 65.9% of stage I cancers), tumor size (78.6% of tumors >2 cm vs 64.7% of tumors <or=2 cm), and location (83.3% of central lesions vs 68% of peripheral lesions) and was found to be independent of histologic tumor type (78.4% of squamous cell carcinomas vs 71.5% of adenocarcinomas, 74.5% of small cell carcinomas, and 75% of large cell carcinomas).

CONCLUSIONS

The findings of the current study suggested the important potential of sputum cytology for lung cancer detection and risk assessment across all stages, histologic types, tumor sizes, and locations. However, the high sensitivities in this study were achieved with a level of scrutiny not feasible in the laboratory routine. The diagnostic potential of sputum cytology may be exploited better through the standardization and automation of sputum preparation and analysis.

Gene expression profiles in peripheral blood mononuclear cells can distinguish patients with non-small cell lung cancer from patients with nonmalignant lung disease

Early diagnosis of lung cancer followed by surgery presently is the most effective treatment for non-small cell lung cancer (NSCLC). An accurate, minimally invasive test that could detect early disease would permit timely intervention and potentially reduce mortality. Recent studies have shown that the peripheral blood can carry information related to the presence of disease, including prognostic information and information on therapeutic response. We have analyzed gene expression in peripheral blood mononuclear cell samples including 137 patients with NSCLC tumors and 91 patient controls with nonmalignant lung conditions, including histologically diagnosed benign nodules. Subjects were primarily smokers and former smokers. We have identified a 29-gene signature that separates these two patient classes with 86% accuracy (91% sensitivity, 80% specificity). Accuracy in an independent validation set, including samples from a new location, was 78% (sensitivity of 76% and specificity of 82%). An analysis of this NSCLC gene signature in 18 NSCLCs taken presurgery, with matched samples from 2 to 5 months postsurgery, showed that in 78% of cases, the signature was reduced postsurgery and disappeared entirely in 33%. Our results show the feasibility of using peripheral blood gene expression signatures to identify early-stage NSCLC in at-risk populations.

The use of volumetric CT as an imaging biomarker in lung cancer

RATIONALE AND OBJECTIVES

Lung cancer is the leading cause of cancer death in the United States. Mortality outcomes have improved only modestly over the past 30 years. There is intense focus on the development of better treatments for lung cancer. Major issues include the cost and time duration of the clinical trials required to establish the utility of a drug so that it can be formally approved by regulatory agencies. In clinical settings, biomarkers that accelerate assessments of responses to treatment could benefit patients by providing earlier diagnoses of progressive disease, particularly when there are multiple options for treatment, and the effects of toxicity from one treatment tend to limit the ability to administer the next line of therapy.

MATERIALS AND METHODS

Quantifying longitudinal changes in tumor volumes using computed tomography could eventually become a more useful surrogate endpoint for assessing tumor responses or progression events than simple unidimensional measurements.

RESULTS

The authors review the historical development of response measurements in lung cancer, set out the medical context for specifying volumetric imaging requirements and goals, compare volumetric technique to conventional methods, and identify the imaging profiles being pursued.

CONCLUSION

The Quantitative Imaging Biomarkers Alliance is investigating volumetric computed tomographic acquisition and analytic methods to increase the analytic power per subject enrolled in clinical trials to reduce the number of total subjects needed or shorten the length of time an individual needs to be followed to reliably establish drug response.

DNA methylation-based biomarkers for early detection of non-small cell lung cancer: an update

Lung cancer is the number one cancer killer in the United States. This disease is clinically divided into two sub-types, small cell lung cancer, (10–15% of lung cancer cases), and non-small cell lung cancer (NSCLC; 85–90% of cases). Early detection of NSCLC, which is the more common and less aggressive of the two sub-types, has the highest potential for saving lives. As yet, no routine screening method that enables early detection exists, and this is a key factor in the high mortality rate of this disease. Imaging and cytology-based screening strategies have been employed for early detection, and while some are sensitive, none have been demonstrated to reduce lung cancer mortality. However, mortality might be reduced by developing specific molecular markers that can complement imaging techniques. DNA methylation has emerged as a highly promising biomarker and is being actively studied in multiple cancers. The analysis of DNA methylation-based biomarkers is rapidly advancing, and a large number of potential biomarkers have been identified. Here we present a detailed review of the literature, focusing on DNA methylation-based markers developed using primary NSCLC tissue. Viable markers for clinical diagnosis must be detectable in 'remote media' such as blood, sputum, bronchoalveolar lavage, or even exhaled breath condensate. We discuss progress on their detection in such media and the sensitivity and specificity of the molecular marker panels identified to date. Lastly, we look to future advancements that will be made possible with the interrogation of the epigenome.

Identification of a panel of sensitive and specific DNA methylation markers for squamous cell lung cancer

Background

Lung cancer is the leading cause of cancer death in men and women in the United States and Western Europe. Over 160,000 Americans die of this disease every year. The five-year survival rate is 15% – significantly lower than that of other major cancers. Early detection is a key factor in increasing lung cancer patient survival. DNA hypermethylation is recognized as an important mechanism for tumor suppressor gene inactivation in cancer and could yield powerful biomarkers for early detection of lung cancer. Here we focused on developing DNA methylation markers for squamous cell carcinoma of the lung. Using the sensitive, high-throughput DNA methylation analysis technique MethyLight, we examined the methylation profile of 42 loci in a collection of 45 squamous cell lung cancer samples and adjacent non-tumor lung tissues from the same patients.

Results

We identified 22 loci showing significantly higher DNA methylation levels in tumor tissue than adjacent non-tumor lung. Of these, eight showed highly significant hypermethylation in tumor tissue (p < 0.0001): GDNF, MTHFR, OPCML, TNFRSF25, TCF21, PAX8, PTPRN2 and PITX2. Used in combination on our specimen collection, this eight-locus panel showed 95.6% sensitivity and specificity.

Conclusion

We have identified 22 DNA methylation markers for squamous cell lung cancer, several of which have not previously been reported to be methylated in any type of human cancer. The top eight markers show great promise as a sensitive and specific DNA methylation marker panel for squamous cell lung cancer.

Exhaled breath analysis: novel approach for early detection of lung cancer

Lung cancer is a leading cause of cancer death, with the prognosis adversely affected by late diagnosis. Early diagnosis of lung cancer is desirable, but current evidence does not support the application of screening with techniques such as chest radiography, sputum cytology or computed tomography. Breath analysis, which includes gaseous phase analysis that measures volatile organic compounds using electronic noses, exhaled nitric oxide, and exhaled breath condensate (EBC), has been proposed as a non-invasive and simple technique to investigate neoplastic processes in the airways. EBC can be easily collected by breathing into a cooling system that condenses the water vapour in the breath. EBC has already been demonstrated to be useful in investigating inflammatory and oxidative stress changes in various respiratory conditions as it contains measurable mediators of airway inflammation and oxidative stress markers. Furthermore, EBC has also been shown to be a useful method to monitor severity of diseases such as asthma and to act as a surrogate measure of compliance to medical therapy. Presently, there still remains a relative paucity of lung cancer research involving EBC. However, since EBC is a simple, non-invasive technique that can be easily performed, even in ill patients, it has the potential to be validated for use in screening for the early diagnosis of lung cancer.

Optimization of image acquisition techniques for dual-energy imaging of the chest

Experimental and theoretical studies were conducted to determine optimal acquisition techniques for a prototype dual-energy (DE) chest imaging system. Technique factors investigated included the selection of added x-ray filtration, kVp pair, and the allocation of dose between low- and high-energy projections, with total dose equal to or less than that of a conventional chest radiograph. Optima were computed to maximize lung nodule detectability as characterized by the signal-difference-to-noise ratio (SDNR) in DE chest images. Optimal beam filtration was determined by cascaded systems analysis of DE image SDNR for filter selections across the periodic table (Z(filter) = 1-92), demonstrating the importance of differential filtration between low- and high-kVp projections and suggesting optimal high-kVp filters in the range Z(filter) = 25-50. For example, added filtration of approximately 2.1 mm Cu, approximately 1.2 mm Zr, approximately 0.7 mm Mo, and approximately 0.6 mm Ag to the high-kVp beam provided optimal (and nearly equivalent) soft-tissue SDNR. Optimal kVp pair and dose allocation were investigated using a chest phantom presenting simulated lung nodules and ribs for thin, average, and thick body habitus. Low- and high-energy techniques ranged from 60-90 kVp and 120-150 kVp, respectively, with peak soft-tissue SDNR achieved at [60/120] kVp for all patient thicknesses and all levels of imaging dose. A strong dependence on the kVp of the low-energy projection was observed. Optimal allocation of dose between low- and high-energy projections was such that approximately 30% of the total dose was delivered by the low-kVp projection, exhibiting a fairly weak dependence on kVp pair and dose. The results have guided the implementation of a prototype DE imaging system for imaging trials in early-stage lung nodule detection and diagnosis.

Beliefs among Physicians in the Diagnostic and Therapeutic Approach to Non-small Cell Lung Cancer

PURPOSE

The American College of Chest Physicians (ACCP) has established evidence-based guidelines for the evaluation and treatment of patients with lung cancer. Physicians' beliefs and practice patterns may differ significantly from established guidelines. We conducted a survey to assess and compare physician beliefs against the evidence-based guidelines.

METHODS

A survey was sent by electronic mail (e-mail) in March 2006 to 2100 randomly selected physicians who were members of the ACCP practicing in the United States, followed by two reminder e-mails.

RESULTS

Three hundred forty-seven surveys were completed and evaluable. The majority (84%) of the respondents reported having read, consulted, or used the guidelines to set practice policies, and 75% found the guidelines helpful. The respondents' practice beliefs were in agreement with the guidelines on the evaluation of operable patients with enlarged mediastinal lymph nodes, the role of chemotherapy in the treatment of stage III disease, and the evaluation of a solitary pulmonary nodule. Nevertheless, a significant percentage of respondents' practice beliefs differed from the guidelines on issues such as screening for lung cancer, the survival benefit of chemotherapy in stage IV disease, and postoperative radiation therapy. Only a minority of respondents believed that chemotherapy improved quality of life in stage IV disease. The survey results indicate that there has been acceptance of the adjuvant chemotherapy and increasing integration of positron emission tomography in the evaluation of a solitary pulmonary nodule and in staging the mediastinum.

CONCLUSIONS

The majority of physicians found the evidence-based guidelines beneficial; nevertheless, practice beliefs differ from the guidelines in select areas.

CT-guided intervention with low radiation dose: feasibility and experience

OBJECTIVE

The purpose of this study was to evaluate the feasibility of performing CT-guided interventional procedures with a very low radiation dose.

MATERIALS AND METHODS

We performed 291 CT-guided interventional procedures using a low dose of radiation. The subjects were 165 men and 126 women 22-89 years old with a mean age of 65 years. CT fluoroscopy was not used. The procedures were 201 percutaneous biopsies and 90 percutaneous aspiration or drainage procedures. Before the procedure, images were obtained with standard mAs of 175-250 mAs. All subsequent CT was performed at a reduced mAs. Technical success of catheter placement and biopsy was calculated, and the results were compared with those of procedures performed over the previous 12 months with standard radiation doses. Patient weight, lesion size, and number of CT acquisitions needed to complete the procedure were recorded.

RESULTS

All but three aspiration or drainage procedures performed at 30 mAs were successful, for a success rate of 96.7%. The technical success rate of biopsy performed at 30 mAs was 93.5%. In the cases of 13 patients undergoing biopsy, the masses were not identified with low-dose technique, and these procedures were completed at a higher dose. Results were independent of patient weight and lesion size. The technical success rate was 98% for percutaneous drainage performed at a standard radiation dose in the 12 months before introduction of the low-dose technique. The technical success rate was 87.5% for biopsy performed at a standard radiation dose in the 12 months before introduction of the low-dose technique. The complication rate of the low-dose technique was comparable to that of the standard-dose technique.

CONCLUSION

Low-dose radiation technique using 30 mAs results in technical success for both catheter placement and percutaneous biopsy comparable to standard radiation dose.

Should we screen for occupational lung cancer with low-dose computed tomography?

OBJECTIVE

The objective of this study was to assess the potential value of screening for occupational lung cancer through the use of low-dose computed tomography (LDCT).

METHODS

A literature review of Medline was conducted to assess: 1) screening studies of occupational lung cancer that used LDCT; 2) screening studies of nonoccupational lung cancer that used LDCT; and 3) position papers of medical professional societies and nongovernmental health organizations that have addressed the value of screening for lung cancer with LDCT.

RESULTS

No screening studies of occupational lung cancer with LDCT were uncovered; however, numerous observational and population-based studies have addressed the value of screening for lung cancer among cigarette smokers. Results of these studies are difficult to interpret in light of numerous biases associated with these types of studies. No randomized, controlled studies on screening for lung cancer have been published at this time. No professional, governmental, or nonprofit health organization recommends screening asymptomatic people at risk of lung cancer with LDCT at this time.

CONCLUSION

In the absence of randomized, controlled studies that can address biases commonly encountered in observational and population-based studies, it is unclear whether LDCT reduces mortality from lung cancer. The National Cancer Institute is sponsoring a randomized, controlled study of over 50,000 current and former smokers with the results expected in 2009.

Screening for lung cancer

The lethality of lung cancer is related to the advanced stage at diagnosis. Initial studies have demonstrated that screening computed tomography (CT) is effective in diagnosing lung cancer at an earlier stage when compared with current clinical practice, however the best clinical approach for screening detected nodules has to be defined. The population to be identified as high risk should be over 50 years of age and should have smoked at least one pack/day for 20 years. CT protocols should use multidetector CT, low dose and a 2.5 reconstruction interval. Diagnostic work-up on detected nodules should be designed according to size and consider CT at 3 or 12 months to evaluate doubling time, CT enhancement, PET/CT and/or FNAB or VATS. The prevalence of lung cancer in the screened population is 1.1%–2.7%, and the incidence is 0.2%–1.1%. Eighty-one percent of cancers are diagnosed in stage I. The percentage of surgery performed for benign lesions ranges from 21% to 55%. In our series, the overall mortality rate was 3.2% in 5 years. The results of randomized clinical studies, when available, will assess the real efficacy of CT in reducing lung cancer related mortality.

p16INK4A and CDH13 hypermethylation in tumor and serum of non-small cell lung cancer patients

Aberrant promoter hypermethylation of several known or putative tumor suppressor genes occurs frequently during the etiopathogenesis of lung cancer and is a promising tool for cancer detection. In the present study, promoter hypermethylation of p16INK4A and CDH13 genes was investigated in tumor tissue and in matched serum from 61 patients with histologically confirmed non-small cell lung cancer. Using a fluorescence-based method of methylation-specific PCR (F-MSP), methylation of p16INK4A and CDH13 was detected in 79% and 66% of tumors, respectively, and was not significantly related to conventional clinicopathological characteristics of patients or tumors. Methylation of both genes was observed in 52% of tumors and of at least one gene in 92% of lesions. In matched serum, hypermethylation of p16INK4A and CDH13 was observed in 26% and 23% of patients, respectively, but as they were not associated, the methylation of at least one gene was detected in 39% of patients. In conclusion, the frequency of p16INK4A or CDH13 hypermethylation in patient serum, together with evidence of their early occurrence in lung cancerogenesis and the total lack of methylation in serum from healthy individuals, offer a promising tool for non invasive early detection of lung cancer.

Limitations of Screening for Lung Cancer with Low-Dose Spiral Computed Tomography

Past lung cancer screening trials in the United States with chest X-ray and sputum cytology were not able to show any decrease in lung cancer mortality; however, these trials are over 20 years old. Recent follow-up of the Mayo Lung Project showed a better survival from lung cancer in the screened arm, but no difference in overall mortality, suggesting an overdiagnosis of nonfatal cancers. Recent reports of low radiation dose spiral computed tomography (CT) chest screening for lung cancer have shown that CT screening detects cancers at a smaller size than chest X-rays. To date, there have been no randomized trials of CT versus observation or chest radiographs for screening purposes. All data available thus far on CT screening are from phase II proof-of-principle trials. The major limitations of CT screening, discussed here, include (a) a high rate of nodule detection: over 50% of participants will have at least one noncalcified nodule; (b) resulting follow-up CT scans, associated with increased costs; (c) cost and morbidity of biopsy or resection of benign noncalcified nodule (20-25% of such procedures in several trials); and (d) a small, but difficult to quantify, risk of cancer associated with multiple follow-up CT scans.