The Mayo Lung Project for early detection and localization of bronchogenic carcinoma: a status report

Impact of CT screening in lung cancer: Scientific evidence and literature review

The treatment of lung cancer has improved significantly in recent years however, lung cancer remains as a leading cause of cancer-related mortality worldwide. Lung cancer screening has been explored, over the past several decades, as a means of reducing lung cancer mortality, to identify asymptomatic disease when it is potentially curable. The National Lung Screening Trial (NLST) established that low-dose computed tomography (LDCT) scans of the chest can be instrumental in reducing lung cancer mortality but the criteria for screening implemented in this trial may not be equitably sensitive across racial and sex subpopulations. Furthermore, the high false detection rate reported in this trial has raised concerns regarding overdiagnosis with LDCT alone. The aim of this review is to summarize the history of lung cancer screening trials, limitations of lung cancer screening, the impact of alternative risk prediction models in reducing disparities, and the use of biomarkers in conjunction with imaging to improve diagnostic authenticity.

Progress and prospects of early detection in lung cancer

Lung cancer is the leading cause of cancer-related death in the world. It is broadly divided into small cell (SCLC, approx. 15% cases) and non-small cell lung cancer (NSCLC, approx. 85% cases). The main histological subtypes of NSCLC are adenocarcinoma and squamous cell carcinoma, with the presence of specific DNA mutations allowing further molecular stratification. If identified at an early stage, surgical resection of NSCLC offers a favourable prognosis, with published case series reporting 5-year survival rates of up to 70% for small, localized tumours (stage I). However, most patients (approx. 75%) have advanced disease at the time of diagnosis (stage III/IV) and despite significant developments in the oncological management of late stage lung cancer over recent years, survival remains poor. In 2014, the UK Office for National Statistics reported that patients diagnosed with distant metastatic disease (stage IV) had a 1-year survival rate of just 15-19% compared with 81-85% for stage I.

Computed tomographic screening for lung cancer: the Mayo Clinic experience

The Mayo Clinic has been involved in screening for lung cancer since the lung cancer project in 1971. The Mayo Clinic recently completed a study of more than 1500 patients with low-dose computed tomographic (CT) screening for lung cancer. Results showed that more than 75% of patients in the screening program had a lung nodule but only a small percentage had lung cancer. As others have found, screening with low-dose CT finds patients with lung cancer at an earlier stage and hopefully will increase the cure rate.

Overdiagnosis in low-dose computed tomography screening for lung cancer

IMPORTANCE

Screening for lung cancer has the potential to reduce mortality, but in addition to detecting aggressive tumors, screening will also detect indolent tumors that otherwise may not cause clinical symptoms. These overdiagnosis cases represent an important potential harm of screening because they incur additional cost, anxiety, and morbidity associated with cancer treatment.

OBJECTIVE

To estimate overdiagnosis in the National Lung Screening Trial (NLST).

DESIGN, SETTING, AND PARTICIPANTS

We used data from the NLST, a randomized trial comparing screening using low-dose computed tomography (LDCT) vs chest radiography (CXR) among 53 452 persons at high risk for lung cancer observed for 6.4 years, to estimate the excess number of lung cancers in the LDCT arm of the NLST compared with the CXR arm.

MAIN OUTCOMES AND MEASURES

We calculated 2 measures of overdiagnosis: the probability that a lung cancer detected by screening with LDCT is an overdiagnosis (PS), defined as the excess lung cancers detected by LDCT divided by all lung cancers detected by screening in the LDCT arm; and the number of cases that were considered overdiagnosis relative to the number of persons needed to screen to prevent 1 death from lung cancer.

RESULTS

During follow-up, 1089 lung cancers were reported in the LDCT arm and 969 in the CXR arm of the NLST. The probability is 18.5% (95% CI, 5.4%-30.6%) that any lung cancer detected by screening with LDCT was an overdiagnosis, 22.5% (95% CI, 9.7%-34.3%) that a non-small cell lung cancer detected by LDCT was an overdiagnosis, and 78.9% (95% CI, 62.2%-93.5%) that a bronchioalveolar lung cancer detected by LDCT was an overdiagnosis. The number of cases of overdiagnosis found among the 320 participants who would need to be screened in the NLST to prevent 1 death from lung cancer was 1.38.

CONCLUSIONS AND RELEVANCE

More than 18% of all lung cancers detected by LDCT in the NLST seem to be indolent, and overdiagnosis should be considered when describing the risks of LDCT screening for lung cancer.

Screening for lung cancer

BACKGROUND

This is an updated version of the original review published in The Cochrane Library in 1999 and updated in 2004 and 2010. Population-based screening for lung cancer has not been adopted in the majority of countries. However it is not clear whether sputum examinations, chest radiography or newer methods such as computed tomography (CT) are effective in reducing mortality from lung cancer.

OBJECTIVES

To determine whether screening for lung cancer, using regular sputum examinations, chest radiography or CT scanning of the chest, reduces lung cancer mortality.

SEARCH METHODS

We searched electronic databases: the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2012, Issue 5), MEDLINE (1966 to 2012), PREMEDLINE and EMBASE (to 2012) and bibliographies. We handsearched the journal Lung Cancer (to 2000) and contacted experts in the field to identify published and unpublished trials.

SELECTION CRITERIA

Controlled trials of screening for lung cancer using sputum examinations, chest radiography or chest CT.

DATA COLLECTION AND ANALYSIS

We performed an intention-to-screen analysis. Where there was significant statistical heterogeneity, we reported risk ratios (RRs) using the random-effects model. For other outcomes we used the fixed-effect model.

MAIN RESULTS

We included nine trials in the review (eight randomised controlled studies and one controlled trial) with a total of 453,965 subjects. In one large study that included both smokers and non-smokers comparing annual chest x-ray screening with usual care there was no reduction in lung cancer mortality (RR 0.99, 95% CI 0.91 to 1.07). In a meta-analysis of studies comparing different frequencies of chest x-ray screening, frequent screening with chest x-rays was associated with an 11% relative increase in mortality from lung cancer compared with less frequent screening (RR 1.11, 95% CI 1.00 to 1.23); however several of the trials included in this meta-analysis had potential methodological weaknesses. We observed a non-statistically significant trend to reduced mortality from lung cancer when screening with chest x-ray and sputum cytology was compared with chest x-ray alone (RR 0.88, 95% CI 0.74 to 1.03). There was one large methodologically rigorous trial in high-risk smokers and ex-smokers (those aged 55 to 74 years with ≥ 30 pack-years of smoking and who quit ≤ 15 years prior to entry if ex-smokers) comparing annual low-dose CT screening with annual chest x-ray screening; in this study the relative risk of death from lung cancer was significantly reduced in the low-dose CT group (RR 0.80, 95% CI 0.70 to 0.92).

AUTHORS' CONCLUSIONS

The current evidence does not support screening for lung cancer with chest radiography or sputum cytology. Annual low-dose CT screening is associated with a reduction in lung cancer mortality in high-risk smokers but further data are required on the cost effectiveness of screening and the relative harms and benefits of screening across a range of different risk groups and settings.

Respiratory Tract and Mediastinum

Normal cytology, abnormal and atypical cells, non-cellular components, and infectious cell changes are largely described together with benign, malignant, and neuroendocrine lesions regarding exfoliative and aspiration cytology of the lung. A separate section broadly addresses diagnostic findings and differential diagnoses in bronchoalveolar washings.

The section ‘Fine needle aspiration biopsy of mediastinal disorders’ covers in particular biopsy techniques, accuracy of liquid-based cytology, and the complex lesions of the thymus gland. Cytodiagnostic algorithms of the major benign and malignant pulmonary and mediastinal lesions and their respective differential diagnoses are additionally presented in synoptic setups.

Development and evaluation of a computer-aided diagnostic scheme for lung nodule detection in chest radiographs by means of two-stage nodule enhancement with support vector classification

PURPOSE

To develop a computer-aided detection (CADe) scheme for nodules in chest radiographs (CXRs) with a high sensitivity and a low false-positive (FP) rate.

METHODS

The authors developed a CADe scheme consisting of five major steps, which were developed for improving the overall performance of CADe schemes. First, to segment the lung fields accurately, the authors developed a multisegment active shape model. Then, a two-stage nodule-enhancement technique was developed for improving the conspicuity of nodules. Initial nodule candidates were detected and segmented by using the clustering watershed algorithm. Thirty-one shape-, gray-level-, surface-, and gradient-based features were extracted from each segmented candidate for determining the feature space, including one of the new features based on the Canny edge detector to eliminate a major FP source caused by rib crossings. Finally, a nonlinear support vector machine (SVM) with a Gaussian kernel was employed for classification of the nodule candidates.

RESULTS

To evaluate and compare the scheme to other published CADe schemes, the authors used a publicly available database containing 140 nodules in 140 CXRs and 93 normal CXRs. The CADe scheme based on the SVM classifier achieved sensitivities of 78.6% (110/140) and 71.4% (100/140) with averages of 5.0 (1165/233) FPs/image and 2.0 (466/233) FPs/image, respectively, in a leave-one-out cross-validation test, whereas the CADe scheme based on a linear discriminant analysis classifier had a sensitivity of 60.7% (85/140) at an FP rate of 5.0 FPs/image. For nodules classified as "very subtle" and "extremely subtle," a sensitivity of 57.1% (24/42) was achieved at an FP rate of 5.0 FPs/image. When the authors used a database developed at the University of Chicago, the sensitivities was 83.3% (40/48) and 77.1% (37/48) at an FP rate of 5.0 (240/48) FPs/image and 2.0 (96/48) FPs/image, respectively.

CONCLUSIONS

These results compare favorably to those described for other commercial and non-commercial CADe nodule detection systems.

Sojourn time and lead time projection in lung cancer screening

OBJECTIVES

We investigate screening sensitivity, transition probability and sojourn time in lung cancer screening for male heavy smokers using the Mayo Lung Project data. We also estimate the lead time distribution, its property, and the projected effect of taking regular chest X-rays for lung cancer detection.

METHODS

We apply the statistical method developed by Wu et al. [1] using the Mayo Lung Project (MLP) data, to make Bayesian inference for the screening test sensitivity, the age-dependent transition probability from disease-free to preclinical state, and the sojourn time distribution, for male heavy smokers in a periodic screening program. We then apply the statistical method developed by Wu et al. [2] using the Bayesian posterior samples from the MLP data to make inference for the lead time, the time of diagnosis advanced by screening for male heavy smokers. The lead time is distributed as a mixture of a point mass at zero and a piecewise continuous distribution, which corresponds to the probability of no-early-detection, and the probability distribution of the early diagnosis time. We present estimates of these two measures for male heavy smokers by simulations.

RESULTS

The posterior sensitivity is almost symmetric, with posterior mean 0.89, and posterior median 0.91; the 95% highest posterior density (HPD) interval is (0.72, 0.98). The posterior mean sojourn time is 2.24 years, with a posterior median of 2.20 years for male heavy smokers. The 95% HPD interval for the mean sojourn time is (1.57, 3.35) years. The age-dependent transition probability is not a monotone function of age; it has a single maximum at age 68. The mean lead time increases as the screening time interval decreases. The standard error of the lead time also increases as the screening time interval decreases.

CONCLUSION

Although the mean sojourn time for male heavy smokers is longer than expected, the predictive estimation of the lead time is much shorter. This may provide policy makers important information on the effectiveness of the chest X-rays and sputum cytology in lung cancer early detection.

Abreugrafia sistemática em massa: inviabilidade econômica e eventuais perigos da exposição a radiações

É descrita a descoberta, por Manoel de Abreu, da roentgenfotografia e sua aplicação maciça na população brasileira onde muitas vezes, por exigência legal, crianças, jovens, mulheres grávidas eram submetidos a exames repetidos e, freqüentemente, desnecessários. Com as explosões atômicas de Hiroshima e Nagasaki e o conhecimento de que mesmo doses mínimas de radiações podem condicionar sérios riscos somáticos e genéticos, a abreugrafia sistemática passou a constituir séria preocupação para os sanitaristas, uma vez que as vantagens, que são poucas, oferecidas por este método diagnóstico são contrabalançadas pelo seu alto custo e pelo risco que oferece às populações. Com, base na literatura e em particular em declaração especifica da Organização Mundial de Saúde, é proposta a abolição da abreugrafia sistemática, com a eliminação, na legislação brasileira, dos dispositivos que a tornam obrigatória em numerosas eventualidades.

Chemoprevention Strategies for Patients with Lung Cancer in the Context of Screening

Despite major advances in the treatment and management of lung cancer, most patients with lung cancer eventually die of this disease. Because conventional therapies have failed to make a major impact on survival, newer approaches are necessary in the battle against lung cancer. Better understanding of molecular biology of several tumors has led to novel targeted therapeutic approaches with potential utility in cancer treatment in general and lung cancer in particular. In addition to smoking cessation, targeting individuals at high risk by use of early detection or aiming at reversal of premalignant lesions seem like attractive strategies. In light of the noted improvement in molecular diagnostic tools and targeted therapies, the question of chemoprevention in the context of early detection deserves a closer look. In this article, we review what has been achieved in the area of chemoprevention and discuss possible prospects that may help reduce lung cancer mortality in the context of early detection.

Screening for lung cancer

BACKGROUND

While population based screening for lung cancer has not been adopted by most countries, it is not clear whether sputum examinations, chest radiography or newer methods such as computed tomography are effective in reducing mortality from lung cancer.

OBJECTIVES

To determine whether screening for lung cancer using regular sputum examinations or chest radiography or CT chest reduces lung cancer mortality.

SEARCH STRATEGY

Electronic databases (the Cochrane Central Register of Controlled Trials, MEDLINE, PREMEDLINE and EMBASE; 1966 to July 2000) ), bibliographies, hand searching of a journal and discussion with experts were used to identify published and unpublished trials.

SELECTION CRITERIA

Controlled trials of screening for lung cancer using sputum examinations, chest radiography or CT chest.

DATA COLLECTION AND ANALYSIS

Intention to screen analysis was performed. Where there was significant statistical heterogeneity relative risks were reported using the random effects model, but for other outcomes the fixed effect model was used.

MAIN RESULTS

Seven trials were included (6 randomised controlled studies and 1 non-randomised controlled trial) with a total of 245,610 subjects. There were no studies with an unscreened control group. Frequent screening with chest x-rays was associated with an 11% relative increase in mortality from lung cancer compared with less frequent screening (RR 1.11, CI: 1.00-1.23). A non statistically significant trend was observed to reduced mortality from lung cancer when screening with chest x-ray and sputum cytology was compared with chest x-ray alone (RR 0.88, CI:0.74-1.03). Several of the included studies had potential methodological weaknesses. There were no controlled studies of spiral CT.

REVIEWER'S CONCLUSIONS

The current evidence does not support screening for lung cancer with chest radiography or sputum cytology. Frequent chest x-ray screening might be harmful. Further, methodologically rigorous trials are required.

Radiologic screening for lung cancer

Lung cancer is the leading cause of cancer death. A number of screening trials have been carried out over the past two decades and have failed to demonstrate a reduction of lung cancer-related mortality. Recent advances in new forms of technology--spiral low-dose CT--have resuscitated interest in screening programs. Preliminary results are promising but the outstanding question is whether the magnitude of improvement is sufficient to affect a measurable reduction in lung cancer mortality?

Screening for lung cancer

BACKGROUND

The effectiveness of screening for lung cancer with chest radiography, sputum cytology or spiral CT has not been established.

OBJECTIVES

To determine whether screening for lung cancer using regular sputum examinations or chest radiography or CT chest reduces lung cancer mortality.

SEARCH STRATEGY

Electronic databases, bibliographies, hand searching of a journal and discussion with experts were used to identify published and unpublished trials.

SELECTION CRITERIA

Controlled trials of screening for lung cancer using sputum examinations, chest radiography or CT chest.

DATA COLLECTION AND ANALYSIS

Intention to screen analysis was performed. Where there was significant statistical heterogeneity relative risks were reported using the random effect model, but for other outcomes the fixed effect model was used.

MAIN RESULTS

Seven trials were included (6 randomised controlled studies and 1 non-randomised controlled trial) with a total of 245,610 subjects. There were no studies with an unscreened control group. Frequent screening with chest x-rays was associated with an 11% relative increase in mortality from lung cancer compared with less frequent screening (RR 1.11, CI: 1.00-1.23). A non statistically significant trend was observed to reduced mortality from lung cancer when screening with chest x-ray and sputum cytology was compared with chest x-ray alone (RR 0.88, CI:0.74-1.03). Several of the included studies had potential methodological weaknesses. There were no controlled studies of spiral CT.

REVIEWER'S CONCLUSIONS

The current evidence does not support screening for lung cancer with chest radiography or sputum cytology. Frequent chest x-ray screening might be harmful. Further, methodologically rigorous trials are required.

Measuring effectiveness of lung cancer screening: from consensus to controversy and back

BACKGROUND

While intense controversy exists regarding screening for breast, colorectal, and prostate cancer, a consensus exists regarding lung cancer screening. All organizations recommend against any efforts to detect early lung cancer because each of four randomized controlled trials (RCTs) has failed to demonstrate a significant reduction in lung cancer mortality as a result of screening.

SYNTHESIS

Disease-specific mortality is assumed to represent the best measure of screening effectiveness in RCTs, because it is not subject to confounding by lead time, length, or overdiagnosis biases. However, the effects of these biases are predictable, so accurate assessments of the degree of confounding by these biases can be made. Moreover, the ability of mortality to accurately reflect cancer death rates depends on the ability of randomization to create experimental and control populations that have an equal risk of dying of the disease under study, except insofar as early detection may reduce that risk. Because the majority of participants in screening trials never develop the disease under investigation, small absolute differences in disease risk between groups often persist despite randomization, and such differences translate into much larger proportional differences in the size of subgroups at risk for disease-specific mortality. This effect confounds the ability of disease-specific mortality to accurately measure screening effectiveness.

RESULTS

A total of 18 RCTs have been conducted to evaluate screening for breast, colorectal, and lung cancer. In the only two RCTs that reported a significant mortality reduction for screening mammography in breast cancer, and in the one RCT that reported a significant mortality reduction for fecal occult blood screening in colorectal cancer, population differences led mortality comparisons to overestimate the effectiveness of screening. In lung cancer, no significant mortality reductions have been reported (to my knowledge), but in the two RCTs most directly addressing the effectiveness of chest radiograph (CXR) screening, population differences led mortality comparisons to underestimate the ability of CXRs to reduce the risk of dying of lung cancer. Although mortality is believed to be the best measure of outcome, not a single example can be cited as definitive proof of efficacy for any screening strategy. Thus, screening cannot be recommended for any cancer on the basis of consistent reductions in mortality in RCTs.

ANALYSIS

Current policy, which calls for no early detection efforts for lung cancer, implicitly accepts the validity of two contradictory assertions. Conventional wisdom maintains that lung cancer is a highly virulent disease and that metastases are present at inception; accordingly, early detection is ineffective. However, RCTs suggest that lung cancer is an indolent disease and that radiographically detected lesions are clinically unimportant; accordingly, early detection is unnecessary. Such contradictions mandate some rethinking of the fundamental assumptions underlying screening evaluation.

CONCLUSIONS

Considerable evidence suggests that annual CXR screening could result in a dramatic reduction in lung cancer mortality in our society. However, proper interpretation of the data depends completely on how screening effectiveness is measured. Given the enormous public health importance of this issue, a consensus conference is recommended to determine whether lung cancer screening can save lives.

Localization of occult bronchogenic carcinoma by bronchography

Bronchography is seldom recommended today to localize radiographically and bronchoscopically occult bronchogenic carcinoma. We report a case in which bronchography promptly localized such a tumor that had been occult to multiple bronchoscopies and chest computed tomograms (CTs). The patient is free of recurrence 32 months after lobectomy. Bronchography should be considered when bronchoscopies and CT fail to reveal a radiographically occult carcinoma.

Screening for lung cancer. A critique of the Mayo Lung Project

The National Cancer Institute of the United States recently sponsored three large-scale, randomized controlled trials of screening for early lung cancer. The trials were conducted at the Johns Hopkins Medical Institutions, the Memorial Sloan-Kettering Cancer Center, and the Mayo Clinic. Participants were middle-aged and older men who were chronic heavy cigarette smokers and thus at high risk of developing lung cancer. Screening procedures were chest radiography and sputum cytology, the only screening tests of established value for detecting early stage, asymptomatic lung cancer. In the Hopkins and Memorial trials the study population was offered yearly chest radiography plus sputum cytology every 4 months. The control population was offered yearly chest radiography only. In these trials the addition of sputum cytology appeared to confer no lung cancer mortality rate advantage. The Mayo Clinic trial compared offering chest radiography and sputum cytology every 4 months to offering advice that the two tests be obtained once a year. This trial demonstrated significantly increased lung cancer detection, resectability, and survivorship in the group offered screening every 4 months compared with the control group. However, there was no significant difference in lung cancer mortality rate between the two groups. The statistical power of these trials was somewhat limited. Nevertheless, results do not justify recommending large-scale radiologic or cytologic screening for early lung cancer at this time.

Diagnosis of peripheral lung cancer using a new type of endoscope

A new fiberoptic bronchoscope, the BF-2.2T, has been designed to go through the 2.6-mm channel of the conventional fiberoptic bronchoscope (Olympus BF-1T20). It measures 2.2 mm in outer diameter; it has a visual angle of 75 degrees, a range of observation of 3 to 50 mm, an effective length of 1,150 mm, and a total length of 1,400 mm. It bends at 120 degrees in an upward direction and at 120 degrees in a downward direction. The 2.2-mm tip of the BF-2.2T bends like a conventional fiberoptic bronchoscope, and this is the main characteristic of this instrument. The BF-2.2T facilitates clinically satisfactory observation and photography, as a method for detecting peripheral lung cancer.

Lung cancer in Australia

Lung cancer is the leading cause of death of cancer in Australian men and the third leading cause in Australian women. Efforts are being made to reduce the incidence of this disease by smoking-cessation programmes and improved industrial hygiene, and these measures need to be encouraged strongly by all sectors of the community. On a population basis, insufficient evidence is available to justify screening procedures for the early detection of lung cancer in "at-risk" groups. Cure is possible by surgical resection in early cases. Improvements in therapeutic results with traditional cancer treatments largely have reached a plateau, but a number of newer therapies, and combinations of standard therapies, currently are being evaluated. Of particular interest is concurrent radiotherapy and chemotherapy in localized non-small-cell lung cancer; laser "debulking" in conjunction with radiotherapy in non-small-cell lung cancer, and biological response-modifying agents in non-small-cell and small-cell lung cancer. It is important that data be collected adequately to define epidemiological changes and to evaluate treatment results (including repeat bronchoscopy, to assess local control of tumour), and that the quality of life is recorded and reported in the evaluation process. Finally, phase-III studies in lung-cancer treatments require adequate numbers of subjects to enable meaningful conclusions to be achieve objectives within a reasonable study period.

Screening for lung cancer

Lung cancer incidence is increasing. Survivability has increased over the last few years particularly in certain subsets and has also been shown to increase with early detection. Chest X-ray and sputum cytology have been the mainstays of screening programs. Although survival is increased, overall mortality rates seem unchanged except in certain subsets. Whether the addition of serum markers or use of monoclonal antibodies, automated cytological, and computer-aided techniques will show decrease in mortality remains to be documented. We recommend yearly chest X-rays, sputum cytology in high-risk patients, i.e., age greater than 65, greater than 20 year history smoking, other significant carcinogenic exposure. Serum markers, monoclonal antibodies, and advanced, automated cytology methods are yet to be tested and therefore should be considered in clinical trials only.

Screening for gastric cancer

Mass screening for gastric cancer in Japan has been conducted nationwide since 1960. The total number of examinees in 1985 amounted to 5,161,876 and 6,240 cases (0.12%) of gastric cancer were detected. Approximately half of these cases were early stage cancers. According to the studies of mass gastric screening in the Miyagi Prefecture, Japan, the sensitivity of the screening test by the indirect x-ray method was 82.4%, and the specificity was 77.2%. The positive predictive value was 1.78%. Recently, mortality from gastric cancer has been decreasing in Japan. Many studies have been carried out to investigate the relationship between the decreasing trend of mortality from cancer of the stomach and the effectiveness of mass gastric screening. From these studies and from time trend analyses of incidence and death rates, case-control studies, nonexperimental cohort studies, etc., it is believed that mass screening for gastric cancer is effective in reducing the death rate from cancer at this site.

Lung cancer detection. Results of a randomized prospective study in Czechoslovakia

A randomized prospective study of lung cancer detection was begun in 1976 to evaluate semiannual screening by radiologic and sputum cytologic study in comparison to screening at a 3-year interval, and to no screening. In a high-risk population of 6364 men (aged 40 to 64 years), the initial prevalence of lung cancer was 0.28% (18 cases), the annual incidence was 0.35% per year (66 cases during 3 years), the proportion of Stage I cases was 31% (26/84), and Stage II was 17% (14/84), "curative" resections were 27% (23/84), and 5-year survival was 23% (19/84). The study confirmed the ability of radiologic screening to detect lung cancer at an earlier stage when treatment by resection can be accomplished. The fate of a high-risk population submitted to screening was better than that of a population with no screening where lung cancer was discovered by symptoms, accidental x-rays, or at autopsy. A matter of lesser importance was the frequency of screening. The absolute numbers of 5-year survivors detected by screening were practically the same for either compared screening frequency.

The impact of routine admission chest x-ray films on patient care

We evaluated the impact of routine chest x-ray films, obtained on admission, on the treatment of patients on internal medicine wards of the Veterans Administration Medical Center, Long Beach, California--a population known to have a high prevalence of cardiopulmonary disease. The reasons for ordering chest films were determined prospectively, and three Department of Medicine faculty members reviewed the charts of admitted patients to determine the impact of chest-film results on patient care. Routine chest x-ray films were ordered for 294 (60 per cent) of the 491 patients studied. Abnormalities were noted in 106 (36 per cent) of these 294 patients. The findings were previously known, chronic, and stable in 86 patients; they were new in only 20. Treatment was changed because of chest-film results in only 12 (4 per cent) of the patients. In only one of these patients would appropriate treatment probably have been omitted if a chest film had not been obtained, and the patient's outcome was not improved by the treatment instituted. We conclude that the impact of routine admission chest x-ray films on patient care is very small, even in a population with a high prevalence of cardiopulmonary disease. We recommend that such films not be ordered solely because of admission.

Roentgenographically occult lung cancer: pathologic findings and frequency of multicentricity during a 10-year period

During the first 10 years of the Mayo Lung Project, 68 roentgenographically inapparent ("occult") lung cancers were localized and apparently completely resected. A pathologic classification was developed based on depth of tumor infiltration. The five categories were (1) in situ carcinoma confined to surface epithelium or ducts of mucous glands or acini (23 cancers), (2) intramucosal invasion not greater than 0.1 cm from mucosal surface (12 cancers), (3) invasion to bronchial cartilages (11 cancers), (4) invasion to full thickness of bronchial wall (10 cancers), and (5) extrabronchial invasion (12 cancers). Multicentricity of lung cancer was studied in 54 patients, none of whom had a history of cancer of the respiratory tract, and all of whom had had "complete" surgical resection of the initial occult lung cancer (or cancers). Neoplasms that were initially multicentric occurred in 4 patients, and a subsequent primary lung cancer developed in 11. The rate of detection of second primary lesions was 42 per 1,000 person-years of observation. A high incidence of unresectable cancers and a low survival rate were noted among patients who had a subsequent primary tumor. These findings were primarily attributable to invasiveness of the subsequent primary cancer or to respiratory insufficiency that resulted from obstructive lung disease or previous pulmonary resection. Because of the high risk of development of a second primary cancer after initial surgical resection, it is important to treat the initial occult cancer as conservatively as possible consistent with "cure."

Fluorescence bronchoscopy in the localization of bronchogenic carcinoma

Fluorescence bronchoscopy using hematoporphyrin derivative as a tumor marker has been developed for localization of early bronchogenic carcinoma. Recent clinical results have been obtained with a krypton laser and a fused quartz fiber illumination system, which is clearly superior to the mercury vapor lamp system used previously. Fifteen patients have been examined, two with the laser. The potential of the technique is demonstrated by a case study of a patient with positive sputum cytology and a negative chest radiograph. The small early invasive tumor could be detected only with difficulty by subtle mucosal changes under white light bronchoscopy. Positive fluorescence was observed in the suspicious area. Malignancy was confirmed by biopsy and histologic examination upon subsequent lobectomy.

The costs and effects of screening for cancer among asbestos-exposed workers

Several million workers previously exposed to asbestos are at risk each year for developing asbestosis or cancer as a result of this exposure. We have reviewed the data on the general effectiveness of screening for the two most common cancers found in these workers (lung cancer and colo-rectal cancer) and have compared the relative benefits expected from screening workers for colon or lung cancer 10, 15, 20 or 25 yr after their initial exposure. Although lung cancer is common, there is little evidence at present that screening for this disease is effective in reducing mortality. Colon cancer is less common, there is more evidence that screening is effective, and the relatively high risk of dying from this disease in asbestos workers makes screening useful. The cost per additional year of life extended by screening is only a few hundreds of dollars, making colon cancer screening programs for asbestos workers considerably more cost-effective than most other screening programs. We conclude that occupational safety agencies should consider implementing screening programs for colon cancer in workers exposed to asbestos over 10 yr ago.

Time and place for sputum cytology in the diagnosis of lung cancer

Despite ready access to medical care 91% of patients dying of lung cancer derived from a population of just under 400 000 are shown to have presented too late for other than palliative treatment. As the incidence and death rates from lung cancer in the district were very similar, few survivors can be expected. Morphological confirmation of the diagnosis was available in 96% of cases. The first positive morphological diagnosis was obtained from sputum cytology taken on admission in 69% of all cases and in 77% of those in whom there had been delay in diagnosis. More extensive use of this investigation on an outpatient basis is urged.

Detection of true pathologic stage I lung cancer in a screening program and the effect on survival

One-hundred-sixty-nine lung cancers have occurred to date among 10,040 cigarette smoking men who participated in the New York Lung Cancer Detection Program. Almost 40% of the cases, 65, were still Stage I when their disease was diagnosed; 62 had thoracotomy and resection, and in 57, mediastinal node dissection confirmed that the mediastinum was free of metastases ("true pathologic" Stage I). Fifty-four of the 62 (87%) are still alive at this time, while only 15 of 104 (14%) of those with Stage II and III lung cancers are alive. Only two patients of the 62 in Stage I who were treated by resection died of lung cancer, both with T2 tumors. Two others are alive with metastases, one died postoperatively, and five died of other causes without evidence of lung cancer. The estimated probability of survival for true Stage I lung cancer is over 90% at five years, and close to 40% of all lung cancers can be detected in this favorable stage by present radiologic and cytologic screening techniques.

Some results of screening for early lung cancer

Screening for lung cancer is somewhat controversial in that very few evaluations of the screening process have been made, and even fewer have involved the use of concomitant, unscreened controls. This report of the Mayo Lung Project provides evaluation of a randomly selected 4500 clinic patients, offered screening for lung cancer at four-month intervals for six years. Another 4500 randomly selected controls not offered screening were merely observed. Good screening is defined, the Mayo project is evaluated, and puzzling results are presented and discussed. From the screened group, 98 new cases of lung cancer have been detected, 67 by study screening and 31 by spontaneous reporting of symptoms (15) or by x-ray examinations (16) done in other than study circumstances. From the controls, 64 new lung cancer cases have been detected, 43 by symptoms and 1 by other methods. Lung cancer mortality is 39 for study patients and 41 for controls. There is thus no evidence at this time that early case finding hs decreased mortality from lung cancer.