Lung cancer screening with low-dose CT

Is sCD163 a Clinical Significant Prognostic Value in Cancers? A Systematic Review and Meta-Analysis

Background

Tumor associated macrophages (TAMs), a kind of inflammatory cells in the tumor microenvironment, are crucial for the occurrence and development of various tumors which increased the expression of CD163. Nevertheless, not much has been established regarding soluble CD163 and its connection to tumor diagnosis. In this case, a meta-analysis was conducted to determine the tumor diagnostic importance of serum sCD163.

Methods

In order to assess the correlation between sCD163 and the overall survival (OS) or progression-free survival (PFS) among tumor patients, a systematic perusal of literature published until June 2020 was conducted. Relevant data were primarily obtained from papers that have the following qualifications: 1) a confidence interval (CI) of 95%; 2) a report of the hazard ratios; and, 3) pooled by means of the Mantel-Haenszel random-effect representation.

Results

For the final meta-analysis, eight papers comprised of 1,236 cases were involved. Through pooled investigation, it was determined that a correlation exists between elevated serum sCD163 and worse OS (HR = 2.24, 95% CI: 1.50-3.35, P < 0.001) and PFS (HR = 3.90, 95% CI: 2.33-6.52, P < 0.001) among tumor cases. Subgroup analysis stratified by medium age at diagnosis demonstrated that patients over 60 years old with high sCD163 had worse OS (HR 2.28, 95% CI: 1.58-3.29, P < 0.001) than under 60 (HR 1.43, 95% CI: 1.15-1.77, P = 0.001). Subgroup analysis revealed that analysis method and medium age at diagnosis were the potential source of heterogeneity.

Conclusions

Overall, diagnosis of tumor cases can be adversely determined through substantial sCD163 levels. Consequently, it is encouraged that extensive researches regarding the rates of cancer survival be accomplished.

Analyzing the prognostic value of DKK1 expression in human cancers based on bioinformatics

Background

The Dickkopf1 (DKK1) gene encodes a protein that belongs to the Dickkopf family. The protein can inhibit the Wnt signaling pathway which plays a key role in the carcinogenesis and progression of various types of cancers. Based on this, we hypothesized that the differential expression of DKK1 may figure significantly in cancers by regulating Wnt signaling pathway transduction. In this study, we conducted bioinformatics analysis to evaluate the prognostic and therapeutic value of DKK1 expression level in human cancers.

Methods

The expression level was analyzed by using the Oncomine database and Gene Expression Profiling Interactive Analysis tool. The analysis of prognosis was conducted by using the UALCAN, Gene Expression Profiling Interactive Analysis (GEPIA), and DriverDBv3 databases. We also investigated using DKK1 promoter methylation to define cancer types through the UALCAN database. Meanwhile, the related functional networks of DKK1 were analyzed by using the GeneMANIA interactive tool and Cytoscape software. Furthermore, Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analysis was conducted using the Metascape online website, and we used the cBioPotartal database to explored DKK1 expression, aberrant information, and the co-expression genes in the subgroups of lung cancer. Finally, we performed the overall survival (OS) meta-analysis of the DKK1 expression in lung squamous cell carcinoma (LUSC) via the Lung Cancer Explorer (LCE).

Results

DKK1 was differentially expressed in different types of human cancers. DKK1 was overexpressed in human cancers including head and neck squamous cell carcinoma (HNSC), LUSC, and pancreatic adenocarcinoma (PAAD). Overexpression of DKK1 indicated adverse OS in bladder urothelial carcinoma (BLCA), HNSC, and PADD, but no difference in OS was found between the LUSC and healthy groups. The high expression of DKK1 was also associated with shorter disease-free survival (DFS) in HNSC, LUSC, and PAAD. Gene regulation network analysis indicated that DKK1 was mainly involved in Wnt signaling pathways and several other signaling pathways.

Conclusions

Our findings showed that DKK1 is significantly expressed in various cancers and could be a biomarker for targeted therapy and a predictor for prognosis of these specific cancers. The bioinformatics analysis revealed a significant overexpression of DKK1 in HNSC, LUSC, and PAAD, with DKK1 overexpression being associated with adverse outcome in these patients, but how DKK1 expression levels relate to hematological malignancies and prognosis is still unclear. These new insights into the function of DKK1 may provide a basis for new targeted drug therapy and an avenue for further investigation into the mechanisms underlying carcinogenesis of DKK1 in different cancer types.

Effect of Hybrid Kernel and Iterative Reconstruction on Objective and Subjective Analysis of Lung Nodule Calcification in Low-Dose Chest CT

Objective

To evaluate the differences in subjective calcification detection rates and objective calcium volumes in lung nodules according to different reconstruction methods using hybrid kernel (FC13-H) and iterative reconstruction (IR).

Materials and Methods

Overall, 35 patients with small (< 4 mm) calcified pulmonary nodules on chest CT were included. Raw data were reconstructed using filtered back projection (FBP) or IR algorithm (AIDR-3D; Canon Medical Systems Corporation), with three types of reconstruction kernel: conventional lung kernel (FC55), FC13-H and conventional soft tissue kernel (FC13). The calcium volumes of pulmonary nodules were quantified using the modified Agatston scoring method. Two radiologists independently interpreted the role of each nodule calcification on the six types of reconstructed images (FC55/FBP, FC55/AIDR-3D, FC13-H/FBP, FC13-H/AIDR-3D, FC13/FBP, and FC13/AIDR-3D).

Results

Seventy-eight calcified nodules detected on FC55/FBP images were regarded as reference standards. The calcium detection rates of FC55/AIDR-3D, FC13-H/FBP, FC13-H/AIDR-3D, FC13/FBP, and FC13/AIDR-3D protocols were 80.7%, 15.4%, 6.4%, 52.6%, and 28.2%, respectively, and FC13-H/AIDR-3D showed the smallest calcium detection rate. The calcium volume varied significantly with reconstruction protocols and FC13/AIDR-3D showed the smallest calcium volume (0.04 ± 0.22 mm³), followed by FC13-H/AIDR-3D.

Conclusion

Hybrid kernel and IR influence subjective detection and objective measurement of calcium in lung nodules, particularly when both techniques (FC13-H/AIDR-3D) are combined.

Lung Cancer Stage is an Independent Risk Factor for Surgical Mortality

Aims and Background

To study surgical mortality and evaluate major risk factors, with specific focus on the role of pathological stage in patients undergoing lung cancer resection.

Methods and Study Design

Age, gender, comorbidity, resection volume, experience of the hospital and surgical team have been reported as variables related to postoperative morbidity and mortality in lung cancer. The role of pathological tumor stage on postoperative mortality has never been fully evaluated. The study included 1418 consecutive lung cancer resections performed from 1998 to 2002 in two institutions. The effect of age, gender, comorbidity, resection volume, pathological stage and induction therapies on postoperative mortality was assessed by univariable and multivariable logistic regression analysis.

Results

Postoperative mortality was 1.8% overall, 3.7% (9/243) for pneumonectomy, 1.7% (17/1016) for lobectomy, and null (0/159) for sublobar resections (P = 0.020). At multivariable analysis, cardiovascular comorbidity (P = 0.008), resection volume (P = 0.036) and pathological stage (P = 0.027) emerged as significant predictors of surgical mortality.

Conclusions

Early stage lung cancer resection has a favorable effect on surgical mortality, not only by preventing the need for pneumonectomy, but also by reducing mortality after lobectomy.

Early stages of mesothelioma, screening and biomarkers

The early diagnosis of mesothelioma is notoriously difficult, both from a clinical and pathological perspective. Patients often undergo several medical investigations without definitive diagnosis. The discovery of biomarkers that can be assessed in pleural effusions, histological samples, and serum may assist with the difficult early diagnosis of mesothelioma. In this chapter we focus on those markers that have been examined in the setting of either early diagnosis of mesothelioma in symptomatic individuals or that have been proposed as suitable for screening of asbestos-exposed individuals, with an emphasis on cytology and histology.

A review of patient dose and optimisation methods in adult and paediatric CT scanning

An increasing number of publications and international reports on computed tomography (CT) have addressed important issues on optimised imaging practice and patient dose. This is partially due to recent technological developments as well as to the striking rise in the number of CT scans being requested. CT imaging has extended its role to newer applications, such as cardiac CT, CT colonography, angiography and urology. The proportion of paediatric patients undergoing CT scans has also increased. The published scientific literature was reviewed to collect information regarding effective dose levels during the most common CT examinations in adults and paediatrics. Large dose variations were observed (up to 32-fold) with some individual sites exceeding the recommended dose reference levels, indicating a large potential to reduce dose. Current estimates on radiation-related cancer risks are alarming. CT doses account for about 70% of collective dose in the UK and are amongst the highest in diagnostic radiology, however the majority of physicians underestimate the risk, demonstrating a decreased level of awareness. Exposure parameters are not always adjusted appropriately to the clinical question or to patient size, especially for children. Dose reduction techniques, such as tube-current modulation, low-tube voltage protocols, prospective echocardiography-triggered coronary angiography and iterative reconstruction algorithms can substantially decrease doses. An overview of optimisation studies is provided. The justification principle is discussed along with tools that assist clinicians in the decision-making process. There is the potential to eliminate clinically non-indicated CT scans by replacing them with alternative examinations especially for children or patients receiving multiple CT scans.

High resolution spiral CT for determining the malignant potential of solitary pulmonary nodules: refining and testing the test

BACKGROUND

A solitary pulmonary nodule (SPN) may represent early stage lung cancer. Lung cancer is a devastating disease with an overall 5-year mortality rate of approximately 84% but with early detection and surgery as low as 47%. Currently a contrast-enhanced multiple-row detector CT (MDCT) scan is the first examination when evaluating patients with suspected lung cancer.

PURPOSE

To apply an additional high resolution CT (HRCT) to SPNs to test whether certain morphological characteristics are associated with malignancy, to assess the diagnostic accuracy of HRCT in the characterization of SPNs, and to address the reproducibility of all measures.

MATERIAL AND METHOD

Two hundred and thirteen participants with SPNs were included in a follow-up study. Blinded HRCT images were assessed with regard to margin risk categories (MRCs), calcification patterns and certain other characteristics and overall malignancy potential ratings (MPRs) were given. Morphological characteristics were tested against reference standard and ROC methodology was applied to assess diagnostic accuracy. Reproducibility was measured with Kappa statistics and 95% confidence intervals were computed for all results. Histopathology (90%) and CT follow-up (10%) were used as reference standard.

RESULTS

MRCs (P < 0.001), calcification patterns (P = 0.003), and pleural retraction (P < 0.001) were all statistically significantly associated to malignancy. Reproducibility was moderate to substantial. Sensitivity, specificity, and overall diagnostic accuracy of HRCT were 98%, 23% and 87%, respectively. Reproducibility was substantial.

CONCLUSION

Statistically significant associations between SPN MRCs, calcification patterns, pleural retraction and malignancy were found. HRCT yielded a very high sensitivity and a somewhat lower specificity for malignancy. Reproducibility was high.

Automatic lung segmentation in CT images with accurate handling of the hilar region

A fully automated and three-dimensional (3D) segmentation method for the identification of the pulmonary parenchyma in thorax X-ray computed tomography (CT) datasets is proposed. It is meant to be used as pre-processing step in the computer-assisted detection (CAD) system for malignant lung nodule detection that is being developed by the Medical Applications in a Grid Infrastructure Connection (MAGIC-5) Project. In this new approach the segmentation of the external airways (trachea and bronchi), is obtained by 3D region growing with wavefront simulation and suitable stop conditions, thus allowing an accurate handling of the hilar region, notoriously difficult to be segmented. Particular attention was also devoted to checking and solving the problem of the apparent 'fusion' between the lungs, caused by partial-volume effects, while 3D morphology operations ensure the accurate inclusion of all the nodules (internal, pleural, and vascular) in the segmented volume. The new algorithm was initially developed and tested on a dataset of 130 CT scans from the Italung-CT trial, and was then applied to the ANODE09-competition images (55 scans) and to the LIDC database (84 scans), giving very satisfactory results. In particular, the lung contour was adequately located in 96% of the CT scans, with incorrect segmentation of the external airways in the remaining cases. Segmentation metrics were calculated that quantitatively express the consistency between automatic and manual segmentations: the mean overlap degree of the segmentation masks is 0.96 ± 0.02, and the mean and the maximum distance between the mask borders (averaged on the whole dataset) are 0.74 ± 0.05 and 4.5 ± 1.5, respectively, which confirms that the automatic segmentations quite correctly reproduce the borders traced by the radiologist. Moreover, no tissue containing internal and pleural nodules was removed in the segmentation process, so that this method proved to be fit for the use in the framework of a CAD system. Finally, in the comparison with a two-dimensional segmentation procedure, inter-slice smoothness was calculated, showing that the masks created by the 3D algorithm are significantly smoother than those calculated by the 2D-only procedure.

Cancer screening in renal transplant recipients: what is the evidence?

Increased cancer risk is well established in the renal transplant population. Little, however, is known about the benefits and harms of cancer screening, treatment effectiveness, and the overall cancer prognosis in renal transplant recipients. In this study, we critically appraised guidelines for cancer screening in the renal transplant and general populations using standard criteria for an evidence-based screening program. Guidelines were included when they were applied to adult participants, had objectives specific to cancer screening, and were written in English. Recommendations for breast and colorectal cancer screening in the general population were supported by evidence of cancer-specific mortality benefits from randomized, controlled trials of cancer screening. Convincing evidence from observational studies had demonstrated population cervical cancer screening was effective, also, test performance of mammography, faecal occult blood testing, and Pap smear were accurate. Population breast, colorectal, and cervical cancer screening also appeared to be good value for money in the general population. On the contrary, recommendations for cancer screening in renal transplant recipients were entirely extrapolated from data in the general population. Studies in the general population have led to the development of cancer screening guidelines in transplant recipients. Because of increased cancer risk, differences in diagnostic test performance, competing risks for deaths from causes such as cardiovascular disease and reduced overall life expectancies, validity of their recommendations are uncertain. Future studies are needed to address these issues to provide the necessary evidence for informed decision-making.

Interobserver-variability of lung nodule volumetry considering different segmentation algorithms and observer training levels

OBJECTIVE

The aim of this study was to investigate the interobserver variability of CT based diameter and volumetric measurements of artificial pulmonary nodules. A special interest was the consideration of different measurement methods, observer experience and training levels.

MATERIALS AND METHODS

For this purpose 46 artificial small solid nodules were examined in a dedicated ex-vivo chest phantom with multislice-spiral CT (20 mAs, 120 kV, collimation 16 mm x 0.75 mm, table feed 15 mm, reconstructed slice thickness 1mm, reconstruction increment 0.7 mm, intermediate reconstruction kernel). Two observer groups of different radiologic experience (0 and more than 5 years of training, 3 observers each) analysed all lesions with digital callipers and 2 volumetry software packages (click-point depending and robust volumetry) in a semi-automatic and manually corrected mode. For data analysis the variation coefficient (VC) was calculated in per cent for each group and a Wilcoxon test was used for analytic statistics.

RESULTS

Click-point robust volumetry showed with a VC of <0.01% in both groups the smallest interobserver variability. Between experienced and un-experienced observers interobserver variability was significantly different for diameter measurements (p=0.023) but not for semi-automatic and manual corrected volumetry. A significant training effect was revealed for diameter measurements (p=0.003) and semi-automatic measurements of click-point depending volumetry (p=0.007) in the un-experienced observer group.

CONCLUSIONS

Compared to diameter measurements volumetry achieves a significantly smaller interobserver variance and advanced volumetry algorithms are independent of observer experience.

Usefulness of low-dose CT in the detection of pulmonary metastasis of gestational trophoblastic tumours

AIM

To determine whether a low-dose spiral chest computed tomography (CT) examination could replace standard-dose chest CT in detecting pulmonary metastases in patients with gestational trophoblastic tumour (GTT).

MATERIALS AND METHODS

In a prospective investigation, 67 chest CT examinations of 39 GTT patients were undertaken. All the patients underwent CT examinations using standard-dose (150 mAs, pitch 1, standard reconstruction algorithm) and low-dose (40 mAs, pitch 2, bone reconstruction algorithm) protocols. Two radiologists interpreted images independently. A metastasis was defined as a nodule within lung parenchyma that could not be attributed to a pulmonary vessel. The number of metastases detected with each protocol was recorded. The size of each lesion was measured and categorized as <5, 5-9.9, and > or = 10 mm. Wilcoxon's signed rank test was used to assess the difference between the numbers of lesion detected by the two protocols.

RESULTS

The CT dose index (CTDI) for the standard-dose and low-dose CT protocols was 10.4 mGy and 1.4 mGy, respectively. One thousand, six hundred, and eighty-two metastases were detected by standard-dose CT, and 1460 lesions by the low-dose protocol. The numbers detected by low-dose CT were significantly less than those detected by standard-dose CT (Z=-3.776, p<0.001), especially for nodules smaller than 5mm (Z=-4.167, p<0.001). However, the disease staging and risk score of the patients were not affected by use of the low-dose protocol.

CONCLUSION

Low-dose chest CT can be used as a staging and follow-up procedure for patients with GTT.

Imaging in the diagnosis and treatment of non-small cell lung cancer

The available tools for diagnosing and staging lung cancer patients can be broadly categorized into non-invasive, minimally invasive and invasive (surgical) modalities. Non-invasive modalities include CT and PET. Minimally invasive modalities are endoscopic approaches, including endoscopic ultrasound, endobronchial ultrasound and transbronchial fine needle aspiration without ultrasound guidance. This review focuses on the non-invasive and minimally invasive techniques involving imaging. Application of Bayesian principles indicates that tests with a high sensitivity and specificity for detection of both systemic metastases and mediastinal nodal involvement are required for treatment selection and planning in patients with non-small cell lung cancer who would be considered for treatment with curative intent. Combined PET/CT using the glucose analogue fluorine-18 fluorodeoxyglucose currently provides the best diagnostic performance for this purpose and should now be considered the standard of care for staging non-small cell lung cancer. Endoscopic ultrasound and endobronchial ultrasound have important complementary roles to allow further evaluation of equivocal nodal abnormalities on PET or CT and to allow pathological samples to be obtained. Diagnostic CT has an important role in defining tumour relations for patients deemed suitable for surgical resection and as the initial investigation for patients with potential symptoms of lung cancer or proven lung cancer that would not be considered for curative treatment on medical grounds.

Five-year lung cancer screening experience: CT appearance, growth rate, location, and histologic features of 61 lung cancers

PURPOSE

To retrospectively evaluate the computed tomography (CT)-determined size, morphology, location, morphologic change, and growth rate of incidence and prevalence lung cancers detected in high-risk individuals who underwent annual chest CT screening for 5 years and to evaluate the histologic features and stages of these cancers.

MATERIALS AND METHODS

The study was institutional review board approved and HIPAA compliant. Informed consent was waived. CT scans of 61 cancers (24 in men, 37 in women; age range, 53-79 years; mean, 65 years) were retrospectively reviewed for cancer size, morphology, and location. Forty-eight cancers were assessed for morphologic change and volume doubling time (VDT), which was calculated by using a modified Schwartz equation. Histologic sections were retrospectively reviewed.

RESULTS

Mean tumor size was 16.4 mm (range, 5.5-52.5 mm). Most common CT morphologic features were as follows: for bronchioloalveolar carcinoma (BAC) (n = 9), ground-glass attenuation (n = 6, 67%) and smooth (n = 3, 33%), irregular (n = 3, 33%), or spiculated (n = 3, 33%) margin; for non-BAC adenocarcinomas (n = 25), semisolid (n = 11, 44%) or solid (n = 12, 48%) attenuation and irregular margin (n = 14, 56%); for squamous cell carcinoma (n = 14), solid attenuation (n = 12, 86%) and irregular margin (n = 10, 71%); for small cell or mixed small and large cell neuroendocrine carcinoma (n = 7), solid attenuation (n = 6, 86%) and irregular margin (n = 5, 71%); for non-small cell carcinoma not otherwise specified (n = 5), solid attenuation (n = 4, 80%) and irregular margin (n = 3, 60%); and for large cell carcinoma (n = 1), solid attenuation and spiculated shape (n = 1, 100%). Attenuation most often (in 12 of 21 cases) increased. Margins most often (in 16 of 20 cases) became more irregular or spiculated. Mean VDT was 518 days. Thirteen of 48 cancers had a VDT longer than 400 days; 11 of these 13 cancers were in women.

CONCLUSION

Overdiagnosis, especially in women, may be a substantial concern in lung cancer screening.

Use of modeling to evaluate the cost-effectiveness of cancer screening programs

Cost-effectiveness analysis (CEA) is an analytic tool that provides a framework for comparing the health benefits and resource expenditures associated with competing medical and public health interventions, thereby allowing decision makers to identify interventions that yield the greatest amount of health, given their resource constraints. Models are important components of most, if not all, CEAs, and they play a key role in evaluating the cost-effectiveness of cancer screening programs, in particular. In this article, we describe the basic types of models used to evaluate cancer screening programs and provide examples of the use of models in CEAs and to guide cancer screening policy. Finally, we offer some suggestions for important concepts to consider when interpreting model results.

Mortality and Causes of Death After Multimodality Treatment for Advanced Oral and Oropharyngeal Cancer

PURPOSE

To analyze mortality and causes of death in patients who received preoperative radiochemotherapy and underwent radical surgery for advanced oral or oropharyngeal cancer.

PATIENTS AND METHODS

A total of 222 patients who underwent multimodality treatment from 1990 to 2000 were included in the study. The inclusion criterion was International Union Against Cancer (UICC) disease stage II to IV (T2, 33.3%; T3, 12.6%; T4, 54.1%). Patients received preoperative radiotherapy 50 Gy and concomitant chemotherapy with mitomycin and 5-fluorouracil. Radical local-regional en bloc resection was performed in all patients. Survival status and causes of death were ascertained from the National Health Registry. Death certificates and autopsy reports were consulted when hospital files failed to provide reliable data.

RESULTS

After a median surveillance period of 72.3 months (range, 24 to 152 months), 59% of patients were alive, 21% had died of recurrence, 5% had died perioperatively, and 15% had died from other causes. Of these, a second cancer in the head and neck region or the lower respiratory tract or the upper digestive tract was found in 7.3%. Although 93% of deaths related to recurrent disease occurred within the first 36 months after surgery, the remaining causes of death did not reveal a specific temporal pattern.

CONCLUSION

Favorable survival data were registered for patients with advanced squamous cell carcinoma of the oral cavity who underwent combined treatment protocols. These patients frequently die of comorbidities. Because recurrent disease is a less common cause of mortality than are other causes, the latter should receive attention during surveillance.

Pulmonary Nodules Detected at Lung Cancer Screening: Interobserver Variability of Semiautomated Volume Measurements

PURPOSE

To retrospectively determine interobserver variability of semiautomated volume measurements of pulmonary nodules and the potential reasons for variability.

MATERIALS AND METHODS

The Dutch-Belgian lung cancer screening trial (NELSON) is a lung cancer screening study that includes men between the ages of 50 and 75 years who are current or former heavy smokers. The NELSON project was approved by the Dutch Ministry of Health and the ethics committee of each participating hospital. Informed consent was obtained from all participants. For this study, the authors evaluated 1200 consecutive low-dose computed tomographic (CT) scans of the chest obtained during the NELSON project and identified subjects who had at least one 50-500-mm(3) nodule. One local and one central observer independently evaluated the scans and measured the volume of any detected nodule by using semiautomated software. Noncalcified solid nodules with volumes of 15-500 mm(3) were included in this study if they were fully surrounded by air (intraparenchymal) and were detected by both observers. The mean volume and the difference between both measurements were calculated for all nodules. Intermeasurement agreement was assessed with the Spearman correlation coefficient. Potential reasons for discrepancies were assessed.

RESULTS

There were 232 men (mean age, 60 years; age range, 52-73 years) with 430 eligible nodules (mean volume, 77.8 mm(3); range, 15.3-499.5 mm(3)). Interobserver correlation was high (r = 0.99). No difference in volume was seen for 383 nodules (89.1%). Discrepant results were obtained for 47 nodules (10.9%); in 16 cases (3.7%), the discrepancy was larger than 10%. The most frequent cause of variability was incomplete segmentation due to an irregular shape or irregular margins.

CONCLUSION

In a minority (approximately 11%) of small solid intraparenchymal nodules, semiautomated measurements are not completely reproducible and, thus, may cause errors in the assessment of nodule growth. For small or irregularly shaped nodules, an observer should check the segmentation shown by the program.

Risk-Benefit Analysis of X-Ray Exposure Associated with Lung Cancer Screening in the Italung-CT Trial

OBJECTIVE

Prior analyses of X-ray exposures in lung cancer screening with CT considered the basic acquisition technique in single-detector scanners and the effects of a lifetime screening regimen, whereas the potential benefit in terms of lives saved was not addressed.

MATERIALS AND METHODS

We determined the total-body effective dose of different acquisition techniques for one single-detector and one MDCT scanner and made projections about the cumulative radiation exposure to smokers undergoing four annual CT examinations on the same scanners in the Italung-CT Trial. Combining these data with estimates of radiation-induced fatal cancer and of the benefit of screening, we calculated the risk-benefit ratio for participants in the trial, ex-smokers, and never-smokers.

RESULTS

The cumulative effective doses per 1,000 subjects were 3.3 Sv using an MDCT scanner and 5.8 or 7.1 Sv using a single-detector scanner. Potential fatal cancers associated with radiation exposure were 0.11 per 1,000 subjects for MDCT scanners and 0.20 or 0.24 for single-detector scanners, which is about 10-100 times lower than the number of expected lives saved by screening assuming a 20-30% lung cancer-specific mortality reduction in current smokers. They were, however, of similar magnitude to the lives saved by screening in never-smokers and former smokers assuming a 10% efficacy of screening.

CONCLUSION

MDCT is associated with lower radiation doses than single-detector CT technology. The risk of radiation dose in the Italung-CT Trial is compensated for by the expected benefit. CT screening for lung cancer should not be offered to never-smokers, whereas its recommendation in former smokers is debatable.

Pulmonary nodules: estimation of malignancy at thin-section helical CT--effect of computer-aided diagnosis on performance of radiologists

PURPOSE

To evaluate the effect of a computer-aided diagnosis (CAD) system on the diagnostic performance of radiologists for the estimation of the malignancy of pulmonary nodules on thin-section helical computed tomographic (CT) scans.

MATERIALS AND METHODS

The institutional review board approved use of the CT database; informed specific study-related consent was waived. The institutional review board approved participation of radiologists; informed consent was obtained from all observers. Thirty-three (18 malignant, 15 benign) pulmonary nodules of less than 3.0 cm in maximal diameter were evaluated. Receiver operating characteristic (ROC) analysis with a continuous rating scale was used to compare observer performance for the estimation of the likelihood of malignancy first without and then with the CAD system. The participants were 10 board-certified radiologists and nine radiology residents.

RESULTS

For all 19 participants, the mean area under the best-fit ROC curve (A(z)) values achieved without and with the CAD system were 0.843 +/- 0.097 (standard deviation) and 0.924 +/- 0.043, respectively. The difference was significant (P = .021). The mean A(z) values achieved without and with the CAD system were 0.910 +/- 0.052 and 0.944 +/- 0.040, respectively, for the 10 board-certified radiologists (P = .190) and 0.768 +/- 0.078 and 0.901 +/- 0.036, respectively, for the nine radiology residents (P = .009).

CONCLUSION

Use of the CAD system significantly (P = .009) improved the diagnostic performance of radiology residents for assessment of the malignancy of pulmonary nodules; however, it did not improve that of board-certified radiologists.

Lung Cancer Screening Experience: A Retrospective Review of PET in 22 Non-Small Cell Lung Carcinomas Detected on Screening Chest CT in a High-Risk Population

OBJECTIVE

The objective of our study was to retrospectively review the PET results of non-small cell lung carcinomas detected on screening chest CT in a high-risk population.

CONCLUSION

PET findings were negative in 32% of the cases of non-small cell carcinomas that were detected on screening CT in a high-risk patient population. These tumors were small, low-grade, or both. The most common histology was bronchioloalveolar cell carcinoma. The role of PET in evaluating screening-detected indeterminate nodules in a high-risk population may be more limited than in a general population.

Is There a Role for PET in the Evaluation of Subcentimeter Pulmonary Nodules?

There are little published data available at this time to determine the appropriate role of positron emission tomography (PET) in the evaluation of subcentimeter pulmonary nodules. The sensitivity for malignancy is lower in these smaller lesions, while one would expect the specificity to be higher. Given that the resolution of current generation PET scanners is only 5 to 6 mm, one will be very unlikely to gain useful information from PET for a lesion below 5 mm. For lesions 5 to 10 mm in size, useful information might be gained from PET in those deemed intermediate risk by CT criteria, but this remains to be established. A positive PET in a small, intermediate risk lesion might push one toward biopsy/excision, though a negative PET in such a lesion must be considered to provide no information whatsoever. Even with advances in PET technologies in the future, we feel it is unlikely that PET will evolve a major role in the evaluation of the subcentimeter nodule.

Low-dose multidetector dynamic CT in the breast

This study investigated the feasibility of using low-dose multidetector dynamic computed tomography (CT) scan for imaging breast. We measured the radiation dose using a phantom at low- and standard-dose CT. To compare the image quality at low- and standard-dose CT, we evaluated normal breasts in 57 cases. In 44 cases with breast cancer, we assessed the staging and time-enhancement curves of breast cancer. In conclusion, the low-dose multidetector dynamic CT scan is feasible for the evaluation of the breast, with reduced radiation dose and with similar image quality when compared with standard-dose CT scan. In breast cancers, low-dose dynamic CT could be used for the staging of breast cancer before surgery.

Cost-effectiveness analysis of screening for lung cancer with low dose spiral CT (computed tomography) in the Australian setting

INTRODUCTION

Low dose spiral computed tomography (CT) is a sensitive screening tool for lung cancer that is currently being evaluated in both non-randomised studies and randomised controlled trials.

METHODS

We conducted a quantitative decision analysis using a Markov model to determine whether, in the Australian setting, offering spiral CT screening for lung cancer to high risk individuals would be cost-effective compared with current practice. This exploratory analysis was undertaken predominantly from the perspective of the government as third-party funder. In the base-case analysis, the costs and health outcomes (life-years saved and quality-adjusted life years) were calculated in a hypothetical cohort of 10,000 male current smokers for two alternatives: (1) screen for lung cancer with annual CT for 5 years starting at age 60 year and treat those diagnosed with cancer or (2) no screening and treat only those who present with symptomatic cancer.

RESULTS

For male smokers aged 60-64 years, with an annual incidence of lung cancer of 552 per 100,000, the incremental cost-effectiveness ratio was 57,325 dollars per life-year saved and 105,090 dollars per QALY saved. For females aged 60-64 years with the same annual incidence of lung cancer, the cost-effectiveness ratio was 51,001 dollars per life-year saved and 88,583 dollars per QALY saved. The model was used to examine the relationship between efficacy in terms of the expected reduction in lung cancer mortality at 7 years and cost-effectiveness. In the base-case analysis lung cancer mortality was reduced by 27% and all cause mortality by 2.1%. Changes in the estimated proportion of stage I cancers detected by screening had the greatest impact on the efficacy of the intervention and the cost-effectiveness. The results were also sensitive to assumptions about the test performance characteristics of CT scanning, the proportion of lung cancer cases overdiagnosed by screening, intervention rates for benign disease, the discount rate, the cost of CT, the quality of life in individuals with early stage screen-detected cancer and disutility associated with false positive diagnoses. Given current knowledge and practice, even under favourable assumptions, reductions in lung cancer mortality of less than 20% are unlikely to be cost-effective, using a value of 50,000 dollars per life-year saved as the threshold to define a "cost-effective" intervention.

CONCLUSION

The most feasible scenario under which CT screening for lung cancer could be cost-effective would be if very high-risk individuals are targeted and screening is either highly effective or CT screening costs fall substantially.

Screening for lung cancer: a review

PURPOSE OF REVIEW

After the disappointing results of lung cancer screening trials conducted in the 1960s to the 1980s, a renewed interest in lung cancer screening emerged in the 1990s with the development of new technologies such as low-dose spiral CT. The literature regarding screening with biomarkers and CT continues to expand rapidly.

RECENT FINDINGS

Although the specificity of CT screening is relatively poor, the sensitivity for the detection of early-stage cancers, particularly adenocarcinoma, is considerably superior to that of chest radiography used in older screening trials. The results of uncontrolled cohort studies of CT screening are promising, but such studies are susceptible to screening biases such as overdiagnosis.

SUMMARY

There is insufficient evidence to support widespread screening in current practice. However, randomized controlled trials are now being conducted to determine whether improved detection by CT will translate into reduced lung cancer mortality. Alternative approaches to secondary prevention such as screening with biomarkers, autofluorescence bronchoscopy, and chemoprevention hold great promise for the future but await further development and evaluation in prospective trials.

Utility of the Lateral Chest Radiograph in the Evaluation of Patients With a Positive Tuberculin Skin Test Result *

STUDY OBJECTIVES

In the United States, chest radiographs are performed on patients with positive tuberculin skin test (TST) results. It is not known whether, in addition to a single posteroanterior radiograph, a lateral chest radiograph is clinically indicated or cost-effective. We sought to determine the utility of the lateral chest radiograph in evaluating TST-positive adults.

DESIGN

Cross-sectional study.

SETTING

Tertiary-care hospital.

PATIENTS

Adults with positive TST results.

MEASUREMENTS

Findings on posteroanterior radiographs alone were compared to posteroanterior and lateral chest radiographs.

RESULTS

In 2 of 535 cases (0.4%), lateral chest radiographs revealed a calcified granuloma not visible on posteroanterior radiographs. This finding did not alter patient management. In all other cases, lateral radiographs only confirmed findings seen on posteroanterior chest radiographs.

CONCLUSION

Treatment altering findings were always visible on posteroanterior radiographs alone. These results suggest that lateral chest radiographs are not useful in evaluating adults with positive TST results.

Early lung-cancer detection with spiral CT and positron emission tomography in heavy smokers: 2-year results

BACKGROUND

Low-dose spiral CT of the chest effectively detects early-stage lung cancer in high-risk individuals. The high rate of benign nodules and issues of making a differential diagnosis are critical factors that currently hamper introduction of large-scale screening programmes. We investigated the efficacy of repeated yearly spiral CT and selective use of positron emission tomography (PET) in a large cohort of high-risk volunteers.

METHODS

We enrolled 1035 individuals aged 50 years or older who had smoked for 20 pack-years or more. All patients underwent annual low-dose CT, with or without PET, for 5 years. Lesions up to 5 mm were deemed non-suspicious and low-dose CT was repeated after 12 months (year 2).

FINDINGS

By year 2, 22 cases of lung cancer had been diagnosed (11 at baseline, 11 at year 2). 440 lung lesions were identified in 298 (29%) participants, and 95 were recalled for high-resolution contrast CT. PET scans were positive in 18 of 20 of the identified cancer cases. Six patients underwent surgical biopsy for benign disease because of false-positive results (6% of recalls, 22% of invasive procedures). Complete resection was achieved in 21 (95%) lung cancers, 17 (77%) were pathological stage I (100% at year 2), and the mean tumour size was 18 mm. There were no interval lung cancers in the 2.5 years of follow-up (average time on study from randomisation to last contact), although 19 individuals were diagnosed with another form of cancer (two deaths and 17 non-fatal admissions).

INTERPRETATION

Combined use of low-dose spiral CT and selective PET effectively detects early lung cancer. Lesions up to 5 mm can be checked again at 12 months without major risks of progression.