Limitation of annual screening chest radiography for the diagnosis of lung cancer. A retrospective study

Computer-assisted diagnosis for an early identification of lung cancer in chest X rays

Computer-assisted diagnosis (CAD) algorithms have shown its usefulness for the identification of pulmonary nodules in chest x-rays, but its capability to diagnose lung cancer (LC) is unknown. A CAD algorithm for the identification of pulmonary nodules was created and used on a retrospective cohort of patients with x-rays performed in 2008 and not examined by a radiologist when obtained. X-rays were sorted according to the probability of pulmonary nodule, read by a radiologist and the evolution for the following three years was assessed. The CAD algorithm sorted 20,303 x-rays and defined four subgroups with 250 images each (percentiles ≥ 98, 66, 33 and 0). Fifty-eight pulmonary nodules were identified in the ≥ 98 percentile (23,2%), while only 64 were found in lower percentiles (8,5%) (p < 0.001). A pulmonary nodule was confirmed by the radiologist in 39 out of 173 patients in the high-probability group who had follow-up information (22.5%), and in 5 of them a LC was diagnosed with a delay of 11 months (12.8%). In one quarter of the chest x-rays considered as high-probability for pulmonary nodule by a CAD algorithm, the finding is confirmed and corresponds to an undiagnosed LC in one tenth of the cases.

A Systems Biology and LASSO-Based Approach to Decipher the Transcriptome-Interactome Signature for Predicting Non-Small Cell Lung Cancer

The lack of precise molecular signatures limits the early diagnosis of non-small cell lung cancer (NSCLC). The present study used gene expression data and interaction networks to develop a highly accurate model with the least absolute shrinkage and selection operator (LASSO) for predicting NSCLC. The differentially expressed genes (DEGs) were identified in NSCLC compared with normal tissues using TCGA and GTEx data. A biological network was constructed using DEGs, and the top 20 upregulated and 20 downregulated hub genes were identified. These hub genes were used to identify signature genes with penalized logistic regression using the LASSO to predict NSCLC. Our model’s development involved the following steps: (i) the dataset was divided into 80% for training (TR) and 20% for testing (TD1); (ii) a LASSO logistic regression analysis was performed on the TR with 10-fold cross-validation and identified a combination of 17 genes as NSCLC predictors, which were used further for development of the LASSO model. The model’s performance was assessed on the TD1 dataset and achieved an accuracy and an area under the curve of the receiver operating characteristics (AUC-ROC) of 0.986 and 0.998, respectively. Furthermore, the performance of the LASSO model was evaluated using three independent NSCLC test datasets (GSE18842, GSE27262, GSE19804) and achieved high accuracy, with an AUC-ROC of >0.99, >0.99, and 0.95, respectively. Based on this study, a web application called NSCLCpred was developed to predict NSCLC.

A prospective cohort evaluation of the sensitivity and specificity of the chest X-ray for the detection of lung cancer in symptomatic adults

BACKGROUND

The accuracy of the chest x-ray (CXR) in the identification of lung cancer amongst symptomatic individuals is uncertain.

PURPOSE

To determine the diagnostic accuracy of the CXR for the detection of non-small cell carcinomas (NSCLC) and all primary intrathoracic malignancies.

METHODS

A prospective cohort study of consecutive CXR reports obtained within a primary care open access initiative. Eligibility criteria were symptoms specified by National Institute for Clinical Excellence as indicative of possible lung cancer and age over 50-yrs. A positive test was a CXR which led directly or indirectly to investigation with CT. The reference standards were malignancies observed within a one- or two-year post-test period.

RESULTS

8,948 CXR outcomes were evaluated. 496 positive studies led to a diagnosis of 101 patients with primary intrathoracic malignancy including 80 with NSCLC. Within two-years, a cumulative total of 168 patients with primary intrathoracic malignancies including 133 NSCLC were observed. The sensitivity and specificity for NSCLC were 76% (95 %CI 68-84) and 95% (95 %CI 95-96) within 1-year and 60% (95 %CI 52-69) and 95% (95 %CI 95-96) within 2-years. The 2-yr positive and negative likelihood ratios were 12.8 and 0.4. The results did not differ for NSCLC compared to all primary malignancies. Within this symptomatic population a negative test reduced the 2-year risk of lung cancer to 0.8%.

CONCLUSIONS

A positive test strongly increases the probability of malignancy whereas a negative test does not conclusively exclude the disease. The findings allow the risk of malignancy following a negative test to be estimated.

Effects of toner-handling work on respiratory function, chest X-ray findings, and biomarkers of inflammation, allergy, and oxidative stress: a 10-year prospective Japanese cohort study

Background

Exposure to toner, a substance used in photocopiers and printers, has been associated with siderosilicosis and other adverse effects. However, these findings are limited, and there is insufficient evidence on the long-term effects of toner exposure. Using longitudinal analysis, this study aimed to examine the effects of work involving toner exposure on the respiratory system over time.

Methods

We conducted a prospective cohort study in a Japanese toner and copier manufacturing enterprise between 2003 and 2013. The cohort included a total of 1468 workers, which comprised 887 toner-handling workers and 581 non-toner-handling workers. We subdivided the toner-handling workers into two groups according to the toner exposure concentration, based on the baseline survey in 2003. We compared the chest X-ray results, respiratory function indicators, and serum and urinary biomarkers of inflammation, allergy, and oxidative stress among the three groups: high-concentration toner exposure group, low-concentration toner exposure group, and non-toner-handling group. To consider the effects of individual differences on the longitudinal data, we used a linear mixed model.

Results

Similar chest X-ray results, the biomarkers, and most of the respiratory function indicators were found in the non-toner-handling and toner-handling groups. There were no significant yearly changes in the percentage of vital capacity (%VC) in the high-concentration toner exposure group, while there was a significant yearly increase in %VC in the low-concentration toner exposure group and non-toner-handling group. The yearly change in each group was as follows: high-concentration toner exposure group, − 0.11% (95% confidence interval [CI], − 0.29 to 0.08; P = 0.250); low-concentration toner exposure group, 0.13% (95% CI, 0.09–0.17; P < 0.001); and non-toner-handling group, 0.15% (95% CI, 0.01–0.20; P < 0.001).

Conclusions

In our 10-year prospective study, toner-handling work was not associated with the deterioration of respiratory function and an increase in biomarker values for inflammation, allergy, and oxidative stress. This finding suggests that toner-handling work is irrelevant to the onset of respiratory disease and has minimal adverse effects on the respiratory system under a well-managed work environment.

Supplementary Information

Supplementary information accompanies this paper at10.1186/s12890-020-01320-6.

Non-Small Cell Lung Cancer: Epidemiology, Screening, Diagnosis, and Treatment

Lung cancer remains the leading cause of cancer deaths in the United States. In the past decade, significant advances have been made in the science of non-small cell lung cancer (NSCLC). Screening has been introduced with the goal of early detection. The National Lung Screening Trial found a lung cancer mortality benefit of 20% and a 6.7% decrease in all-cause mortality with the use of low-dose chest computed tomography in high-risk individuals. The treatment of lung cancer has also evolved with the introduction of several lines of tyrosine kinase inhibitors in patients with EGFR, ALK, ROS1, and NTRK mutations. Similarly, immune checkpoint inhibitors (ICIs) have dramatically changed the landscape of NSCLC treatment. Furthermore, the results of new trials continue to help us understand the role of these novel agents and which patients are more likely to benefit; ICIs are now part of the first-line NSCLC treatment armamentarium as monotherapy, combined with chemotherapy, or after definite chemoradiotherapy in patients with stage III unresectable NSCLC. Expression of programmed cell death protein-ligand 1 in malignant cells has been studied as a potential biomarker for response to ICIs. However, important drawbacks exist that limit its discriminatory potential. Identification of accurate predictive biomarkers beyond programmed cell death protein-ligand 1 expression remains essential to select the most appropriate candidates for ICI therapy. Many questions remain unanswered regarding the proper sequence and combinations of these new agents; however, the field is moving rapidly, and the overall direction is optimistic.

Health Effects of Toner Exposure Among Japanese Toner-Handling Workers: A 10-Year Prospective Cohort Study

The main objective of this study was to evaluate the risk of the respiratory diseases, i.e. pneumoconiosis, lung fibrosis, granulomatous pneumonitis, lung cancer and bronchial asthma, which have been reported as related to toner exposure. The second main objective was to clarify the association between toner exposure and parameters related with toner-handling worker's health. We conducted a 10-year prospective cohort study from 2004 to 2013 in 296 Japanese toner-handling workers. The evaluation of toner exposure and medical health check were performed once a year. There was no obvious evidence of occurrence of lung diseases. We also investigated several health parameters to recognize the change of respiratory health before onset of pneumoconiosis, lung fibrosis, lung cancer and bronchial asthma. However there were some sporadic statistically significant findings, to bring all health parameters, we did not find obvious evidence that toner exposure would cause adverse health effects as a whole. We concluded that the possibility that toner exposure would cause adverse health effects was quite low.

Clinical study of asbestos-related lung cancer diagnosed by asbestos medical examination

AIM

People with occupational exposure to asbestos demonstrate a high incidence of lung cancer. Asbestos medical examination for those at risk was implemented as a national policy in Japan. This study aimed to characterize patients with asbestos-related lung cancer who were diagnosed by these examinations.

METHODS

We retrospectively investigated 120 individuals exposed to asbestos who were examined from 2008 to 2016 at our institution. Clinical data, including CT findings and time-related exposure variables, were evaluated. Each asbestos-related change was assigned 1 point if present, and the scores were compared between patients with and without asbestos-related lung cancer using the Mann-Whitney U test and Fisher's exact test.

RESULTS

Five patients were diagnosed with lung cancer, and four underwent surgical treatment. At the time of writing, three of four operated patients were alive without recurrence, with a similar prognosis to patients with lung cancer unrelated to asbestos. Average scores for asbestos-related findings on CT Scan were 1.8 (9/5) for patients with lung cancer and 0.79 (91/115) for those without lung cancer.

CONCLUSION

Patients with lung cancer had significantly more asbestos-related changes on CT scan than those without lung cancer. Concurrent calcified plaque and interstitial changes might be a predictor of lung cancer incidence. Although further investigation with a larger study group is needed, regular medical examination and CT scan every 6 months might contribute to the early detection of lung cancer with asbestos-related changes on CT.

Identifying lung cancer in patients with active pulmonary tuberculosis

The diagnosis of lung cancer can be delayed in patients with a history of infection with pulmonary tuberculosis that present with new lesions on chest imaging, due to a high initial index of suspicion for mycobacterium tuberculosis complex rather than malignancy. This may lead to diagnosis of malignancy at a more advanced stage of the disease with subsequent increased morbidity and mortality. We reviewed the current literature to evaluate various methods of differentiating between a diagnosis of lung cancer and tuberculosis including radiography, computerized tomography (CT), positron emission tomography (PET) and various biological markers. We included only papers published in English. Based on current data, we recommend that patients established as high risk, according to the American Association of Thoracic Surgery, patients with age greater than or equal to 55 years and a smoking history of greater than or equal to 30 pack years, should be assessed with CT for underlying malignancy prior to beginning tuberculosis treatment, even in the presence of a clinical or microbiologic diagnosis of tuberculosis. In patients with equivocal CT findings, we recommend examination of tumor markers miR128, miR210, miR126 along with CEA, if these tests are at the clinician's disposal.

Linkage between Aids Surveillance Systeml and Population-Based Cancer Registry Data in Italy: A Pilot Study in Florence, 1985-90

The role of the Tuscany population-based Cancer Registry (TCR) in the assessment of cancer incidence in AIDS patients, and the completeness of cancer reporting to the Italian AIDS surveillance system (RAIDS) was evaluated through a linkage between the TCR and the RAIDS in the period 1985-90. In the Province of Florence, the incidence of Kaposi's sarcoma in AIDS cases was underestimated by 24% (95% CI; 9.8%-47%; 6/25 cases) by RAIDS in comparison with the TCR. Of kaposi's sarcomas unknown to RAIDS, 2 were incident at the time of AIDS diagnosis (“truly” unreported cases) and 4 were late manifestations of AIDS. Moreover, 1 non-Hodgkin lymphoma unknown to RAIDS and 10 other malignancies (4 lung cancers) were identified through the TCR. In AIDS patients, the incidence of lung cancer was 95-fold (99% CI, 16-310) the expected one on the basis of age-sex-specific incidence rates in the general population of the same area. Altogether, about 25% of AIDS cases developed a cancer during HIV infection. In spite of the small size of the present study, the results confirm the role of population-based cancer registries in the assessment of the occurrence of malignancies in AIDS patients.

A population-based cohort study of chest x-ray screening in smokers: lung cancer detection findings and follow-up

BACKGROUND

Case-control studies of mass screening for lung cancer (LC) by chest x-rays (CXR) performed in the 1990s in scarcely defined Japanese target populations indicated significant mortality reductions, but these results are yet to be confirmed in western countries. To ascertain whether CXR screening decreases LC mortality at community level, we studied a clearly defined population-based cohort of smokers invited to screening. We present here the LC detection results and the 10-year survival rates.

METHODS

The cohort of all smokers of > 10 pack-years resident in 50 communities of Varese, screening-eligible (n = 5,815), in July 1997 was invited to nonrandomized CXR screening. Self-selected participants (21% of cohort) underwent screening in addition to usual care; nonparticipants received usual care. The cohort was followed-up until December 2010. Kaplan-Meier LC-specific survival was estimated in participants, in nonparticipants, in the whole cohort, and in an uninvited, unscreened population (control group).

RESULTS

Over the initial 9.5 years of study, 67 LCs were diagnosed in screening participants (51% were screen-detected) and 178 in nonparticipants. The rates of stage I LC, resectability and 5-year survival were nearly twice as high in participants (32% stage I; 48% resected; 30.5% 5-year survival) as in nonparticipants (17% stage I; 27% resected; 13.5% 5-year survival). There were no bronchioloalveolar carcinomas among screen-detected cancers, and median volume doubling time of incidence screen-detected LCs was 80 days (range, 44-318), suggesting that screening overdiagnosis was minimal. The 10-year LC-specific survival was greater in screening participants than in nonparticipants (log-rank, p = 0.005), and greater in the whole cohort invited to screening than in the control group (log-rank, p = 0.001). This favourable long-term effect was independently related to CXR screening exposure.

CONCLUSION

In the setting of CXR screening offered to a population-based cohort of smokers, screening participants who were diagnosed with LC had more frequently early-stage resectable disease and significantly enhanced long-term LC survival. These results translated into enhanced 10-year LC survival, independently related to CXR screening exposure, in the entire population-based cohort. Whether increased long-term LC-specific survival in the cohort corresponds to mortality reduction remains to be evaluated.

TRIAL REGISTRATION NUMBER

ISRCTN90639073.

Small peripheral lung adenocarcinoma: CT and histopathologic characteristics and prognostic implications

Since the introduction of computed tomography (CT), detection of small lung cancer, especially small peripheral adenocarcinoma, is common. Recently, the morphological characteristics, including thin-section CT and pathologic findings, and prognosis of small peripheral lung adenocarcinomas have been studied extensively. The radiologic and microscopic findings correlate well with each other and are closely associated with tumour prognosis. Most importantly, some subtypes of small lung adenocarcinomas with specific CT or pathologic features are curable. Therefore, all defining characteristics (CT, pathologic and prognostic) of this kind of tumour should be integrated to improve our understanding, provide guidelines for management and accurately assess its prognosis.

Spectrum of diagnostic errors in radiology

Diagnostic errors are important in all branches of medicine because they are an indication of poor patient care. Since the early 1970s, physicians have been subjected to an increasing number of medical malpractice claims. Radiology is one of the specialties most liable to claims of medical negligence. Most often, a plaintiff's complaint against a radiologist will focus on a failure to diagnose. The etiology of radiological error is multi-factorial. Errors fall into recurrent patterns. Errors arise from poor technique, failures of perception, lack of knowledge and misjudgments. The work of diagnostic radiology consists of the complete detection of all abnormalities in an imaging examination and their accurate diagnosis. Every radiologist should understand the sources of error in diagnostic radiology as well as the elements of negligence that form the basis of malpractice litigation. Error traps need to be uncovered and highlighted, in order to prevent repetition of the same mistakes. This article focuses on the spectrum of diagnostic errors in radiology, including a classification of the errors, and stresses the malpractice issues in mammography, chest radiology and obstetric sonography. Missed fractures in emergency and communication issues between radiologists and physicians are also discussed.

[Risk group chest X-ray for the early detection of lung cancer]

In Hungary, one of the most important components of anti-TB fight was the initiation of chest X-ray based obligatory and yearly screening of the population. In the 1970s, approximately the entire adult population was regularly screened for lung diseases. However, with the improvement of TB epidemiology, early detection of lung cancer--as a "byproduct" of X-ray screening--seems to have a growing significance. In the near future, concentration needs to be given to the risk group for lung cancer, namely smokers who are older than 40 years. To demonstrate the advances of the above strategy, we investigated the lung cancer prevalence in Budapest, retrospectively. Based on the data of 2511 patients, we found that 60% of the patients with 5-year survival were identified with screening. The operability rate was 34% in the group of patients identified by screening. This was only 14% in the case of patients who had been identified based on their symptoms at the time of diagnosis. We also found that radical tumor resection offers a significant short-term (3-4 years) survival advantage, because of the long-term recurrence of the tumors, the overall mortality rate remains unchanged in the target population. Based on the current screening data, there is a chance for short-term survival advantage for 5-600 patients in every year. With the screening of the risk population (smokers, >40 years), the operability rate could be improved which, in turn, could offer a prolonged survival for 1100-1200 lung cancer patients.

Sensitivity and specificity of lung cancer screening using chest low-dose computed tomography

Lung cancer screening programmes using chest X-ray and sputum cytology are routinely performed in Japan; however, the efficacy is insufficient. Screening using low-dose computed tomography (CT) is a more effective approach and has the potential to detect the disease more accurately. A total of 7183 low-dose CT screening tests for 4689 participants and 36 085 chest X-ray screening tests for 13 381 participants were conducted between August 1998 and May 2002. Sensitivity and specificity of lung cancer screening were calculated by both the detection method and the incidence method by linkage of the screening database and the Cancer Registry database. The preclinical detectable phase was assumed to be 1 year. Sensitivity and specificity by the detection method were 88.9 and 92.6% for low-dose CT and 78.3 and 97.0% for chest X-ray, respectively. Sensitivity of low-dose CT by the incidence method was 79.5%, whereas that of chest X-ray was 86.5%. Lung cancer screening using low-dose CT resulted in higher sensitivity and lower specificity than traditional screening according to the detection method. However, sensitivity by the incidence method was not as high as this. These findings demonstrate the potential for overdiagnosis in CT screening-detected cases.

Long-term follow-up study of a population-based 1996–1998 mass screening programme for lung cancer using mobile low-dose spiral computed tomography

Early diagnosis and treatment are important for improvement of the low survival rate of patients with lung cancer. The objective of this study was to evaluate the long-term survival rate of patients identified to have lung cancer by our population-based baseline and annual repeat low-radiation dose computed tomography (low-dose CT) screenings, conducted in 1996-1998. A total of 13,037 CT scans were obtained from 5480 subjects (2969 men, 2511 women) aged 40-74 years at the initial CT screening. Lung cancer was detected in 63 subjects (57 were detected by CT scans and underwent surgery; 1 was detected by sputum cytology and underwent surgery; 3 rejected treatment; and 2 were interval cases that developed symptoms prior to the next annual repeat CT screening). Follow-up study included review of medical records. Death certificates were examined to check for any deceased interval case among participants. Postoperative follow-up of the 50 survived patients ranged from 70 to 117 (median, 101) months. Eight patients died during follow-up (6 due to lung cancer from 20 to 67 months after surgery and 2 deaths unrelated to lung cancer, each 7 and 60 months following surgery). Three patients who rejected treatment died 14 months to 6 years after positive screening CT scans, and the 2 interval cases died at each 17 and 30 months, respectively, following negative screening CT scans. Survival was analysed in 59 patients with lung cancer detected by low-dose CT screening (excluding two patients; one was detected by sputum cytology and the other had mass lesion already noted on the chest radiograph of the previous year). The 10-year survival calculated by the Kaplan-Meier method was 83.1% (95% CI: 0.735-0.927) for death from all causes and 86.2% (95% CI: 0.773-0.951) for death from lung cancer. The survival rate was excellent for never-smokers, patients with BAC and adenocarcinoma/mixed types with non-solid CT density pattern, associated with Noguchi's type A or B and pathologic stage IA. A poorer prognosis was noted in smokers with adenocarcinomas/mixed types, associated with part-solid or solid CT density pattern and Noguchi's type C or D. All patients with non-solid tumours measuring 6-13.5mm at presentation are alive, patients with part-solid tumours, measuring 17mm or more, or solid tumours, measuring 13mm or more at presentation were associated with increased risk of lung cancer-related morbidity or mortality. The estimated rate of possible over-diagnosis was 13% in total and we failed to cure 17% of patients encountered in the programme. Low-dose CT screening substantially improves the 10-year survival for lung cancer with minimal use of invasive treatment procedures.

Lung Cancer Screening: Simulations of Effects of Imperfect Detection on Temporal Dynamics

PURPOSE

To use a mathematic model to demonstrate effects of imperfect detection on temporal dynamics of radiologic lung cancer screening.

MATERIALS AND METHODS

Monte Carlo simulations of lung cancer screening programs were performed in subjects at high risk for developing cancer. The effects of detection probabilities, symptomatic presentation of tumors, tumor volume doubling time, and time between screenings were examined. Computed tomography (CT) and chest radiography models were used.

RESULTS

For imperfect detection probabilities, the percentage of subjects with cancers detected with repeated screenings decreased to a steady-state value. The transition period was the period during which screenings were performed and detection rates decreased. At steady-state repeat screening, the proportion of subjects with cancers diagnosed at screening or by means of symptomatic presentation was determined by the annual probability of developing cancer and not by the sensitivity of the screening modality. The sensitivity of the screening technique did affect detected cancer size, number of interval cancers, and total number of cancers observed. CT was used to detect more total cancers over the course of the screening program and cancers with a smaller average size; moreover, fewer interval cancers were observed with CT screening than with chest radiography screening.

CONCLUSION

Lung cancer screening with imperfect detection has a transition period between baseline screening and steady-state behavior of annual screenings. Advantages of CT screening include a decrease in the average cancer size at detection, a decrease in the number of observed interval cancers, and an increase in the total number of cancers observed. Steady-state behavior indicates that long-term trials of screening may not be necessary.

Low-dose computed tomography screening for lung cancer in a general population

RATIONALE AND OBJECTIVES

To report the detection rate for lung cancers in computed tomography (CT) screening in Japanese adults, and to analyze differences in the appearance of the cancers in non-smokers versus smokers.

MATERIALS AND METHODS

Subjects consisted of 7,847 Japanese adults who received low-dose CT screening at least once in a 3-year period. The detection rate of lung cancers and the correlation of imaging, clinical, and pathologic findings of cancers in non-smokers versus smokers were examined.

RESULTS

The detection rate for lung cancer was 1.1% for both non-smokers (45 of 4,251) and smokers (39 of 3,596). The prevalence of well-differentiated adenocarcinomas was greater in non-smokers (88%; 22 of 25) than in smokers (29%; 4 of 14) (P < .001). The prevalence and incidence of pathologic stage IA disease were greater in non-smokers than in smokers (92%; [22 of 24] vs 58% [7 of 12], and 100% [19 of 19] vs 70% [14 of 20]) (both P < .05). The mean size of the tumors in the non-smokers (12.4 mm) was smaller than that in smokers (18.2 mm) (P < .001). The percentage of cancers categorized as pure or mixed ground-glass opacity (86%; 38 of 44) on CT was greater in non-smokers than in smokers (46%; 16 of 35) (P < .001).

CONCLUSION

Most of the lung cancers in non-smokers were slow-growing adenocarcinomas appearing as faint ground-glass opacities on CT, whereas rapidly growing cancers appearing as solid nodules were more commonly seen in smokers.

Lung cancers missed at low-dose helical CT screening in a general population: comparison of clinical, histopathologic, and imaging findings

PURPOSE

To compare clinical, histopathologic, and imaging features of lung cancers missed at low-radiation-dose helical computed tomography (CT).

MATERIALS AND METHODS

Eighty-three primary lung cancers were found during an annual low-dose CT screening program and confirmed histopathologically at either surgery or biopsy. Thirty-two of these lung cancers were missed on 39 CT scans: on 23 scans owing to detection errors and on 16 owing to interpretation errors. The clinical characteristics, CT features, and histopathologic findings of these missed lung cancers were correlated.

RESULTS

All missed cancers were intrapulmonary, and 28 (88%) were stage IA. All 20 detection errors occurred in cases of adenocarcinoma, 17 (85%) of which were well-differentiated tumors and 11 (55%) of which were in nonsmoking women. The mean size of cancers missed owing to detection error, 9.8 mm, was smaller than that of cancers missed owing to interpretation error, 15.9 mm (P <.001). In the detection error group, the percentages of nodules with ground-glass opacity (91%) or judged to be subtle (91%) were greater than those of nodules in the interpretation error group (38% and 25%, respectively) (P <.001). In the detection error group, 83% (19/23) of cancers were overlapped with, obscured by, or similar in appearance to normal structures such as pulmonary vessels. On 14 of the 16 CT scans with which there were interpretation errors, the CT findings mimicked benign disease, and the patients also had underlying lung disease, such as tuberculosis, emphysema, or lung fibrosis.

CONCLUSION

The lung cancers missed at low-dose CT screening in this series generally were very subtle and appeared as small faint nodules, overlapping normal structures, or opacities in a complex background of other disease.

Lung: feasibility of a method for changing tube current during low-dose helical CT

A method for changing the tube current during helical scanning was applied to low-dose computed tomography (CT) in the lung. The changing method resulted in significant equalization of image noise in various lung sections compared with that at scanning with constant tube current. Detectability of nodules was equivalent between 60 mA and the changing method, whereas degradation occurred at 20 mA. This method seems feasible for the low-dose CT of lung cancer screening.

An evaluation of chest X-ray screening for lung cancer in gunma prefecture, Japan: a population-based case-control study

In order to evaluate the efficacy of annual chest X-ray screening for lung cancer, a case-control study was conducted in Gunma Prefecture, Japan. Population-based annual lung cancer screening programmes have been conducted by the local government in Gunma Prefecture since the mid-1970s. A total of 121 case subjects, including 91 high-risk males and 30 non-high-risk females between the ages of 40 and 79 years who died of lung cancer from 1992 to 1997 were evaluated. A total of 536 controls (3-5 controls for each case) were matched to case subjects by gender, year of birth, address and smoking habits. Controls were selected from screening programme lists provided by the local governments. All case subjects were also included on these lists. The smoking-adjusted odds ratio (OR) of lung cancer death for those subjects screened within 12 months prior to diagnosis versus those not screened was 0.68 (95% confidence interval (CI): 0.44-1.05; P=0.084). When the analysis was conducted without matching case and control subjects by smoking habits, the OR was 0.79 (95% CI: 0.53-1.18). When stratified by histological type, the OR was 0.62 (95% CI: 0.31-1.24) for adenocarcinoma, and 1.01 (95% CI: 0.44-2.31) for squamous cell carcinoma. The results of this study suggest 20-30% of deaths attributable to lung cancer, especially adenocarcinoma, might be prevented by annual chest X-rays.

A case-control study of lung cancer screening in Okayama Prefecture, Japan

The effectiveness of lung cancer screening in reducing mortality still remains uncertain. In order to evaluate the efficacy of lung cancer screening, a case-control study was conducted in Okayama Prefecture, Japan. The study area consisted of 34 municipalities where a population-based lung cancer screening had been conducted. Chest X-ray examinations for all participants and sputum cytology for high-risk participants were offered annually. The cases analyzed in this study consisted of 412 individuals aged between 40 and 79 who died of lung cancer. A total of 3490 controls, two to ten for each case matched by gender, year of birth, and living district were randomly collected. Screening histories of cases were compared with those of and matched controls for the identical calendar period prio to diagnosis of the case. Smoking adjusted odds ratio (OR) of death from lung cancer for screened individuals versus unscreened, within 12 months before diagnosis, was calculated as 0.59 (95% confidence interval: 0.46-0.74; P=0.0001). The OR for women (0.39, 95% confidence interval: 0.24-0.64) was lower than that for men (0.67, 95% confidence interval: 0.51-0.87), although both were statistically significant. These results suggest that lung cancer screening contributes to reducing lung cancer mortality by 41%.

High-resolution CT analysis of small peripheral lung adenocarcinomas revealed on screening helical CT

OBJECTIVE

The purpose of this study was to determine the correlation between high-resolution CT morphologic features of small peripheral lung adenocarcinomas and tumor growth patterns.

MATERIALS AND METHODS

We examined high-resolution CT morphologic features of 59 small, surgically resected peripheral lung adenocarcinomas (diameter, 6-20 mm) that were detected on screening for lung cancer using low-dose helical CT. Among these adenocarcinomas, 14 (24%) were visible and 45 (76%) were invisible on conventional chest radiography. The correlation between high-resolution CT morphologic features and tumor growth patterns was analyzed.

RESULTS

Sixteen (94%) of 17 type A (Noguchi's classification) adenocarcinomas appeared as nodules of pure ground-glass attenuation (high-resolution CT type I). Ten (71%) of 14 type B tumors appeared as heterogeneous, low-attenuation nodules (type II). Seven (29%) of 24 type C tumors appeared as nodules with ground-glass attenuation in the periphery and a high-density central zone (type III), and 12 (50%) of 24 type C tumors appeared as homogeneous nodules with soft-tissue density (type IV). Among tumors with a replacement growth pattern, the size and CT values of type C tumors were larger than those of type A or type B tumors (p < 0.05), whereas the percentage of ground-glass attenuation and retained air space in type C tumors was smaller than those in type A or type B tumors (p < 0.01). All (100%) four type D tumors appeared to be homogeneous nodules with soft-tissue density (type IV).

CONCLUSION

Small peripheral lung adenocarcinomas shown on CT exhibit four high-resolution CT patterns that corresponded to the histopathologic findings of different tumor growth patterns.

Further reduction of radiation dose in helical CT for lung cancer screening using small tube current and a newly designed filter

A new aluminum filter, 5.8 mm thick at the center, was designed. The effective energy, exposure dose, absorbed dose, and noise were measured by using low-dose technique, very low-dose technique with a conventional filter, and very low-dose technique with a new filter on a chest phantom. Accuracy of very low-dose computed tomography (CT) with a new filter was compared against standard helical CT in 40 patients and against chest radiography in 35 patients. Effective energies were 42.6 keV and 51.6 keV at a conventional filter and the new filter, respectively. Compared against 20mA with a conventional filter, exposure dose was reduced by 17%, and absorbed dose was equivalent, at 30 mA with the new filter. Noise was improved by 9%. Compared with standard helical CT, the sensitivity, specificity, and accuracy of very-low-dose helical CT were 100%, 88%, and 95%, respectively. Very-low-dose helical CT was found to be significantly superior to chest radiography in the detection of lung cancers. Using a smaller tube current and an appropriate filter allows a further reduction in radiation dose in helical CT for lung cancer screening.

Telemedicine system using computed tomography van of high-speed telecommunication vehicle

The current medical system provides medical services to patients who visit hospitals. However, medical services can be provided at or close to the home of the patient using fully equipped mobile telemedicine systems. Such a system can identify the disease at an early stage, improve quality of life and prognosis through early diagnosis and treatment, and reduce the costs of medical service. Furthermore, the unit can provide mass screenings of the population, as well as full medical service to remote areas. The Telecommunications Advanced Organization of Japan, Matsumoto, Japan, and Shinshu University Hospital, Matsumoto, Japan, established a research center for a unique telemedicine project using a mobile system. The mobile unit consists of a van that houses a spiral computed-tomography (CT) machine and various telecommunications equipment. The unit allows medical examination, CT scanning, and on-line two-way transfer of image data/teleconferencing to a medical center for consultation with various specialists. We have used the system thus far for the early detection of lung cancer through mass screenings over a four-year period in 29 administrative districts. Mass screenings of 19117 residents resulted in the identification of 75 cases of early lung cancer who were later treated by partial pneumonectomy at Shinshu University Hospital and affiliated hospitals. We have also used the system to provide medical services to rural areas, as telemedicine support at remote areas, wintertime telemedicine support to an international sports competition, and various medical services to a home-care facility.

Reproducibility of the WHO/IASLC grading system for pre-invasive squamous lesions of the bronchus: a study of inter-observer and intra-observer variation

AIMS

Although many workers have graded pre-invasive squamous lesions arising in the bronchus, there has been no consensus classification system until the latest edition of the WHO/IASLC histological classification of pulmonary and pleural tumours. Because the value of any such system is dependent on its reproducibility, we have circulated a series of such lesions to a panel of histopathologists to assess interobserver and intra-observer variation when the WHO/IASLC classification was applied.

METHODS AND RESULTS

Colour transparencies of 28 pre-invasive squamous lesions were assessed by six histopathologists (two with a special interest in pulmonary pathology, two generalists and two trainees) on three separate occasions over a period of 3 months, using the criteria of the WHO/IASLC (mild, moderate and severe dysplasia, and in-situ carcinoma). An additional category of metaplasia was added for those cases that showed no dysplasia. Weighted kappa coefficents of agreement (K(w)) were used to evaluate paired observations with a standard quadratic weighting being employed, such that kappa coefficients corresponded to intra-class correlation coefficients. Wilcoxon's sign-ranked test was used to measure the statistical significance of group trends, when comparing kappa values for the three grading systems. Various 3-point systems were also assessed, through combination of the above groups. Intra-observer agreement was substantially better than interobserver variation (mean: 0.71 vs. 0.55). Between the various pathologist groups, inter-observer variation was relatively minor, although intra-observer variation was higher within the trainee pathologist group. Using weighted kappa values, there was no significant difference in either inter-observer or intra-observer agreement between the five point grading system and a 3-point system of metaplasia/mild, moderate and severe/in-situ grades. However, there was a significant increase in variation when a 3-point system of metaplasia/mild, moderate/severe and in-situ carcinoma was used.

CONCLUSION

This study shows levels of interobserver and intra-observer variation similar to those found in other grading systems in histopathology, with no significant decrease in variability found by abridging the system. The WHO/IASLC system is therefore recommended for future use in both clinical and research fields.

Results of three-year mass screening programme for lung cancer using mobile low-dose spiral computed tomography scanner

The aim of this study was to evaluate the usefulness of annual screening for lung cancer by low-dose computed tomography (CT) and the characteristics of identified lung cancers. Subjects consisted of 5483 general population aged 40-74 years, who received initial CT scans in 1996, followed by repeat annual scans for most subjects in 1997 and 1998, with a total of 13 786 scans taken during 1996-1998. Work-up examinations for patients with suspicious lesions were conducted using diagnostic CTs. The initial screening in 1996 detected suspicious nodules in 279 (5.1%) of 5483 subjects, and 22 (8%) were confirmed surgically to have lung cancer. Corresponding figures in 1997 and 1998 screening studies were 173 (3.9%) of 4425 and 25 (14%) of 173, and 136 (3.5%) of 3878 and 9 (7%) of 136, respectively. The sensitivity and specificity of detecting surgically confirmed lung cancer were 55% (22/40) and 95% (4960/5199) in 1996 and 83% (25/30) and 97% (4113/4252) in 1997 screening, respectively. 88% (55/60) of lung cancers identified on screening and surgically confirmed were AJCC stage IA. Our trial allowed detection of nearly 11 times the expected annual number of early lung cancers. Repeat CT allowed the detection of more aggressive, rapidly growing lung cancers, compared to those in the initial screening.

Birth cohort effects on incidence of lung cancers: a population-based study in Nagasaki, Japan

Smoking prevalence remains high (around 60%) among Japanese males, but smoking initiation among males born in the 1930s decreased by approximately 10% due to economic difficulties following World War II. The present study was designed to examine whether this temporary decline in smoking initiation influenced the subsequent incidence of lung cancers, especially adenocarcinoma. Trends of lung cancer incidence by histological type in both sexes were investigated using data from the population-based cancer registry in Nagasaki, Japan, from 1986 through 1995. During this period, 5668 males and 2309 females were diagnosed as having lung cancer, and the overall incidence of lung cancers among both sexes remained stable. However, males aged 55 - 59 years showed a decrease in the age-specific incidence of adenocarcinoma and squamous-cell carcinoma (P < 0.05 and P < 0.01, respectively). In birth cohort analyses, the incidence of adenocarcinoma and squamous-cell carcinoma was lower in the 1935 - 1939 birth male cohort than in the successive cohorts. The incidence of lung cancers among females with low smoking prevalence did not change with birth cohort. The low smoking initiation among the 1935 - 1939 birth male cohort appeared to have resulted in a decreased incidence of adenocarcinoma and squamous cell carcinoma among middle-aged Japanese males. The present study suggests that smoking prevention has an effect in reducing the incidence of lung adenocarcinoma, as well as squamous-cell carcinoma, among smokers.

Lung cancer screening: minimum tube current required for helical CT

PURPOSE

To investigate the minimum tube current required for helical computed tomography (CT) for lung cancer screening.

MATERIALS AND METHODS

Thirty helical scans of the lung were obtained at effective tube currents of 50, 30, 20, 18, 12, 10, and 6 mAs in seven healthy volunteers. Computer-generated nodules 6 mm in diameter that showed ground-glass opacity were superimposed on the images. The image quality and detectability of nodules were evaluated subjectively by six observers. The SDs of measured CT numbers were calculated. The results were analyzed according to location in the lung.

RESULTS

Compared with the subjective quality of images obtained at 50 mAs, the subjective quality of images obtained at 20 mAs was not significantly different. The detectability of nodules was not significantly degraded by reducing the tube current to 20 mAs in the upper zone of the lung, to 12 mAs in the middle zone, or to 18 mAs in the lower zone. The SDs at the apex and base of the lung were larger than those at other levels, and the difference became greater as the dose was reduced.

CONCLUSION

The minimum tube current required for screening helical CT differs for different locations in the lung. An ideal CT protocol for the lung should permit the tube current to be changed during helical scanning.

Videotaped helical CT images for lung cancer screening

PURPOSE

The goal of this work was to determine a radiologist's ability to detect solitary pulmonary nodules on helical CT using both video (cine) viewing and film-based viewing.

METHOD

Sixty-five chest helical CT studies were reviewed. Six radiologists searched for 40 lung nodules on CT images presented in three formats. Film-based viewing of images at 10 and 5 mm increments was performed with a light box. Video viewing of the same examinations was performed in 5 mm increments at 2 frames/s. The area under the receiver operating characteristic curve (Az) measured the observer's ability to detect nodules.

RESULTS

The Az was 0.948 for the video viewing, 0.844 for 5 mm increment film-based viewing, and 0.879 for 10 mm increment film-based viewing. There were no statistically significant differences.

CONCLUSION

Lung nodules can be detected with similar detection rates when viewing conventional film or videotaped helical CT images. Videotaped images incur a lower cost, an important consideration in mass screening for lung cancer.

Characteristics of small lung cancers invisible on conventional chest radiography and detected by population based screening using spiral CT

Conventional chest radiography (CXR) is a poor diagnostic tool for detecting lung cancers at a surgically curable stage. To determine the visibility of peripheral small lung cancers on CXR, we retrospectively examined the usefulness of CXR using a consecutive series of 44 cases detected on CT screening and later confirmed by histopathology. All cases had been detected by low dose CT during a population based screening trial for lung cancer. The control group consisted of 48 chest radiographs of normal subjects. Tumour diameters ranged from 6 mm to 45 mm, with 95% (42/44) < or = 20 mm, and 5% (2/44) > 20 mm. CXR failed to detect 77% (34/44) of all cancers, including 79% (33/42) < or = 20 mm and 50% (1/2) > 20 mm. Of the 42 lung cancers < or = 20 mm, 74% (31/42) were located in the well penetrated lung zones and 71% (22/31) of these were missed on CXR. 26% (11/42) were concealed by hilar vessels, mediastinum, heart or diaphragm, and all (11/11) of these were missed on CXR. 93% (39/42) of the lung cancers < or = 20 mm were adenocarcinomas and 79% (31/39) of these were missed on CXR. 7% (3/42) were epidermoid carcinomas or small cell carcinomas and 66% (2/3) of these were missed on CXR. The overall accuracy of interpretation on CXR for lung cancers was 61%, sensitivity was 23% and specificity 96%. Although there was an association between presence of lung cancer and positive reading of CXR (chi 2 test of association, p < 0.05), the percentage of positive readings was only 23%. Thus, CXR was poor at visualizing CT detectable lung cancers of < or = 20 mm diameter, which are usually of very low density, and cannot be relied upon for detection of surgically curable small lung cancer.

Prognostic markers in resectable non-small cell lung cancer

Numerous prognostic factors have been identified in patients with resectable non-small cell lung cancer (NSCLC) which may enable stratification of patients into subsets indicating risk of recurrence following complete resection. Such prognostic markers include a variety of clinico-pathologic factors such as tumor size, modal status, and histopathologic variables. Several serum tumor markers have also proven useful. Moreover, a wide variety of molecular markers have been described over the last decade, which can be classified as molecular genetic markers, metastatic propensity markers, differentiation markers, and proliferation markers. This article reviews those prognostic markers most likely to prove clinically useful from the perspective of guiding postresection treatment strategies in early stage NSCLC.

Screening for lung cancer. Another look; a different view

PURPOSE

There is widespread acceptance that screening for lung cancer is not indicated, to our knowledge, because no randomized trial has demonstrated a reduction in mortality as a result of screening. The objectives of this work are to review prospective studies on lung cancer screening and to analyze the extent to which known biases may have influenced observed results.

BACKGROUND

Four randomized controlled trials have been conducted. The Memorial-Sloan Kettering and Johns Hopkins Lung Projects compared annual chest radiographs (CXRs) in a control group with CXRs and sputum cytologic findings in an experimental group. Although both studies failed to demonstrate any difference in outcome by the addition of cytologic study to CXR, long-term survival in both studies was approximately three times that predicted by other data. Accordingly, these results are at least consistent with the hypothesis that the screening CXRs may have improved survival. Two randomized trials, the Mayo Lung Project and the Czechoslovak study, compared regular and frequent rescreening CXRs in an experimental group with sporadic and/or infrequent rescreening in a control group.

RESULTS

Both the Mayo and Czech studies demonstrated a striking advantage for screening with respect to stage distribution, resectability, survival, and fatality. Nevertheless, mortality was somewhat higher in the screened groups in both studies. Survival and fatality comparisons in randomized trials can be confounded by overdiagnosis bias, lead-time bias, and length bias, while mortality is not subject to these biases. Accordingly, it is believed that a mortality reduction represents the strongest evidence for screening efficacy. Mortality is directly proportional to cumulative incidence. In both the Mayo and Czech studies, incidence of lung cancer was higher in the screened group. The higher cumulative incidence (which in the Mayo Lung Project was statistically significant) made possible the discordant findings of superior survival/fatality and inferior mortality in the screened populations. Overdiagnosis has been widely accepted to account for the "missing cases" in the control populations in the Mayo and Czech studies. However, epidemiologic and autopsy evidence as well as an outcome analysis of unresected early-stage screen-detected lung cancer demonstrates that screening does not lead to the overdiagnosis of lung cancer. Similarly, lead-time bias and length bias cannot account for the outcome differences in the Mayo Lung Project or Czech study. If survival and fatality comparisons (which suggest a striking benefit from screening) are not biased, then mortality comparisons (which suggest no benefit) cannot accurately reflect lung cancer death rates in these trials. Population heterogeneity may provide an explanation for how outcome differences may have been misrepresented by mortality comparisons in these two trials, as well as other large population-based randomized studies.

CONCLUSIONS

Periodic screening CXRs lead to clinically meaningful improvements in stage distribution, resectability, survival, and fatality in lung cancer. Mortality reductions have not been demonstrated, but mortality did not accurately reflect lung cancer death rates in the Mayo Lung Project and Czechoslovak study. Accordingly, reconsideration of the desirability of periodic CXR screening may be appropriate for individuals at high risk of lung cancer.

Early detection in lung cancer. Case finding and screening

There is general agreement that the most effective approach to lung cancer is primary prevention--stop smoking. Richards has proposed the MVROCST--the Monosyllabic Verbal Response Office Cancer Screening Test: "Do you smoke?" If "yes," intervene. If "no," move on. Ample evidence exists that a clear message from a physician to a patient about the importance of stopping smoking makes a difference. In contrast to the maze of arguments and data on early detection, this is something that each physician clearly can and should do. A reduced risk for lung cancer may begin as early as 5 years after cessation of cigarette use. Huuskonen has proposed conceptualizing screening as a coordinated intervention with the goal of identifying populations at risk and working to modify that risk. Primary prevention should be central to any efforts to reduce mortality from lung cancer, and attention to this area needs to increase despite the difficulties and frustration. Despite declining percentages of smokers in the population as a whole, it is estimated that more than 3000 teenagers become regular smokers each day in the United States. In this environment, the question of whether to recommend a CXR or sputum for early detection is not going to disappear in the near future. The NCI has recognized the persistent and important nature of this debate and is currently funding the Prostate, Lung, Colon and Ovary Cancer Screening Trial. This is a large and powerful randomized study of men and women aged 60 to 74. The lung cancer arm is designed to look at the usefulness of a yearly CXR intervention in reducing cancer-specific mortality. The overall power of the study (based on national mortality data) is 0.99 for a 15% reduction in lung cancer mortality and 0.89 for a 10% reduction, with differentially better sensitivity in men than women. The study is currently in progress at multiple sites and will be completed over the next 12 to 14 years. In the meantime, what is the right approach? It is useful in considering this question to return to the concepts of early detection, screening, and case finding. 1. Early detection in lung cancer remains a concept of uncertain applicability because of the unknowns and variability in the natural history of the disease. The available, accessible, and acceptable detection tools appear to be inadequate by current evidence. This is not a static field, however, and new work in the area of biomarkers carries promise for significantly more sensitive and specific techniques. Tockman and colleagues conclude that early detection is conceptually sound, although not currently practical, and further research may expand the role of intervention. In the end, a judgement on early detection in lung cancer must be linked to the proposed setting--screening or case finding. 2. Screening, defined as the application of a test to the general population to define disease risk further with the implied benefit of improved treatment and outcome, cannot be recommended for lung cancer. This is the perspective of the major organizations cited previously, and it is based on admittedly imperfect but nonetheless convincing data. 3. Case finding, the situation of the patient who seeks care and is available for informed discussion and negotiation on possible testing, is a potentially different situation.(ABSTRACT TRUNCATED)

Lung cancer in West Sweden 1976-1985. A study of trends and survival with special reference to surgical treatment

We reviewed 3 285 consecutive cases of lung cancer diagnosed in West Sweden during the period 1976-1985. Data were collected from the regional cancer registry, the Swedish National Population Registry, and medical records. During the study period, the annual female/male ratio increased from 0.29 to 0.42. In females, there was an increase primarily in the incidence of tobacco-related morphologic tumour types (i.e. squamous and small cell lung cancers). In males, a moderate increase of adenocarcinomas was seen, although squamous cell cancer remained the most common tumour type. The overall 5-year survival rate was 8.3%. In 641 patients (20%) a surgical tumour resection was carried out. The 5-year survival rate following resection was 38%, and the probability of 10-year survival was estimated at 25%. In a multifactorial model including gender, age, histology, pTNM stage and extent of resection, pTNM stage and, to a lesser degree, age were statistically significant independent predictors of postoperative survival. The five-year survival was 57% in stage 1, 21-27% in stage II and IIIa, and 10% in stage IIIb. Of all resected patients, 4.2% died within two months after resection. In males, early postoperative mortality was predicted by preoperative bicycle ergometry. The prognosis in non-resected patients was poor, with only 2% surviving 5 years or longer. In conclusion, the results indicate that some progress has been made with regard to surgical management of lung cancer, but they also point to the fact that the vast majority of patients are not amenable to curative treatments, and that the overall survival in lung cancer has improved only marginally during the last decades.