Lung cancer mortality in the Mayo Lung Project: impact of extended follow-up

Screening for Lung Cancer

BACKGROUND

Lung cancer typically exhibits symptoms only after the disease has spread, making cure unlikely. Because early-stage disease can be successfully treated, a screening technique that can detect lung cancer before it has spread might be useful in decreasing lung cancer mortality.

OBJECTIVES

In this article, we review the evidence for and against screening for lung cancer with low-dose CT and offer recommendations regarding its usefulness for asymptomatic patients with no history of cancer.

RESULTS

Studies of lung cancer screening with chest radiograph and sputum cytology have failed to demonstrate that screening lowers lung cancer mortality rates. Published studies of newer screening technologies such as low-dose CT and "biomarker" screening report primarily on lung cancer detection rates and do not present sufficient data to determine whether the newer technologies will benefit or harm. Although researchers are conducting randomized trials of low-dose CT, results will not be available for several years. In the meantime, cost-effectiveness analyses and studies of nodule growth are considering practical questions but producing inconsistent findings.

CONCLUSIONS

For high-risk populations, no screening modality has been shown to alter mortality outcomes. We recommend that individuals undergo screening only when it is administered as a component of a well-designed clinical trial with appropriate human subjects' protections.

Lung cancer screening

The result of a lung cancer screening program should be fewer lung cancer-specific deaths in the screened population. Studies evaluating chest imaging as a screening tool for lung cancer have not shown a reduction in lung cancer-specific mortality to date. The ability of institutions using chest imaging to meet the criteria for successful screening programs has also been debated. Contentious issues include the presence of an overdiagnosis bias, the ability to find preclinical disease at a curable point in time, the amount of pseudodisease identified, and the cost-effectiveness of screening programs. Current guidelines remain vague as randomized trials are being completed and technologic advances are occurring. The ultimate face of a successful lung cancer screening program is yet to be defined.

Mortality ascertainment of participants in the National Wilms Tumor Study using the National Death Index: comparison of active and passive follow-up results

Long term studies of childhood cancer survivors are hampered by difficulties in tracking young adult participants. After performing a National Death Index (NDI) search we sought to identify which factors best predicted a match among known decedents from the National Wilms Tumor Study (NWTS) and to determine if record linkage could substitute for missing follow-up in a cohort of NWTS survivors. To our knowledge, this is the first study to compare passive mortality follow-up using the NDI to active follow-up of a childhood and young adult population. Records for 984 known decedents and 3,406 subjects whose January 1, 2002 vital status was unknown were sent to the NDI in June 2003. In April 2005 NWTS follow-up records were used to reassess January 1, 2002 vital status. Matches were established for 709 of 789 known decedents (sensitivity 89.9%) with a date of death between 1979 and 2001, the calendar period covered by the NDI at the time of the search. No matches were identified among 1,052 subjects known to be alive in 2002 (specificity 100%). Factors associated with decreased sensitivity were an unknown social security number (sensitivity 87.8%), Hispanic ethnicity (76.4%) and foreign birth (56.5%). For 2,351 subjects with 2002 vital status unknown who had 13,166 pre 2002 person-years of missing observation, only 18 deaths were ascertained by the NDI whereas 79.3 were expected based on NWTS mortality data. Mortality analyses based strictly on NDI search results and those based on NWTS follow-up augmented with NDI search results yielded inflated estimates of the 15 year survival rate when compared with estimates based on NWTS active follow-up. Match rates were comparable to those observed in adult populations. Since the same selection factors were likely associated with NDI failure to match and NWTS loss to follow-up, use of the NDI to fill in missing follow-up data appears unwarranted.

Overall survival in the intervention arm of a randomized controlled screening trial for prostate cancer compared with a clinically diagnosed cohort

OBJECTIVES

This population-based study provides comparisons of prostate cancer characteristics at diagnosis of two cohorts of men from two well-defined geographical areas exposed to different intensities of prostate cancer screening. Overall survival in both cohorts was compared with that in the general population.

METHODS

A cohort of 822 men randomized to the intervention arm of a prostate cancer screening trial and subsequently diagnosed with prostate cancer was compared with a nonrandomized cohort of 947 men who were clinically diagnosed with prostate cancer in a geographically neighboring region. In both cohorts, cases were diagnosed with prostate cancer between January 1989 and December 1997. A partitioning of overall survival by variables associated with cancer onset such as age at diagnosis, stage at diagnosis, and grade at diagnosis was performed.

RESULTS

Age at diagnosis, tumor extent at diagnosis, and grade at diagnosis were significantly different between the screened and clinically diagnosed cohort. The 5- and 10-yr survival rates were higher in the screened cohort than in the clinically diagnosed cohort (88.8% vs. 52.4%, and 68.4% vs. 29.6%, respectively). Significant differences in survival were evident for all age, stage, and grade subgroups, except for metastatic disease at diagnosis.

CONCLUSIONS

Differences in overall survival favoring the screened population were observed for all baseline characteristics (age, stage, and grade of disease), and these variables may all explain differences in overall survival because screening achieves early diagnosis as well as a stage and grade shift. As observed survival rates in the screened population mirrored those within the general population, the contribution of lead time and overdiagnosis to final patient outcome is considered to be large as well.

Autofluorescence bronchoscopy for lung cancer surveillance based on risk assessment

BACKGROUND

This is a preliminary report of an ongoing prospective bimodality lung cancer surveillance trial for high-risk patients. Bimodality surveillance incorporates autofluorescence bronchoscopy (AFB) and spiral CT (SCT) scanning in high-risk patients as a primary lung cancer surveillance strategy, based entirely on risk factors. AFB was used for surveillance and findings were compared with conventional sputum cytology for the detection of malignancy and pre-malignant central airway lesions.

METHODS

402 patients registering at Roswell Park Cancer Institute were evaluated with spirometric testing, chest radiography, history and physical examination, of which 207 were deemed eligible for the study. For eligibility, patients were required to have at least two of the following risk factors: (1) > or =20 pack year history of tobacco use, (2) asbestos-related lung disease on the chest radiograph, (3) chronic obstructive pulmonary disease with a forced expiratory volume in 1 s (FEV(1)) <70% of predicted, and (4) prior aerodigestive cancer treated with curative intent, with no evidence of disease for >2 years. All eligible patients underwent AFB, a low-dose SCT scan of the chest without contrast, and a sputum sample was collected for cytological examination. Bronchoscopic biopsy findings were correlated with sputum cytology results, SCT-detected pulmonary nodules and surveillance-detected cancers. To date, 186 have been enrolled with 169 completing the surveillance procedures.

RESULTS

Thirteen lung cancers (7%) were detected in the 169 subjects who have completed all three surveillance studies to date. Pre-malignant changes were common and 66% of patients had squamous metaplasia or worse. Conventional sputum cytology missed 100% of the dysplasias and 68% of the metaplasias detected by AFB, and failed to detect any cases of carcinoma or carcinoma-in-situ in this patient cohort. Sputum cytology exhibited 33% sensitivity and 64% specificity for the presence of metaplasia. Seven of 13 lung cancers (58%) were stage Ia or less, including three patients with squamous cell carcinoma. Patients with peripheral pulmonary nodules identified by SCT scanning of the chest were 3.16 times more likely to exhibit pre-malignant changes on AFB (p<0.001).

CONCLUSION

Bimodality surveillance will detect central lung cancer and pre-malignancy in patients with multiple lung cancer risk factors, even when conventional sputum cytology is negative. AFB should be considered in high-risk patients, regardless of sputum cytology findings.

Incidental findings with cardiac CT evaluation: should we read beyond the heart?

Cardiac computed tomographic angiography (CTA) allows for simultaneous evaluation of the lung fields and associated structures. There is a debate as to the benefit of or need for routine overread of the lung fields for incidental findings. The possible improvement in cancer diagnosis with routine overreads is balanced against the major limitations of CT lung screening. Current limitations include (a) a high rate of nodule detection given that >50% of participants may have at least one noncalcified nodule; (b) the increased costs and radiation exposure associated with the resulting follow-up CT scans; (c) the cost and the morbidity of follow-up, including further testing, as well as biopsy or resection of benign noncalcified nodule (at least 25% of such procedures in several trials); (d) a small but difficult to quantify potential risk of cancer associated with multiple follow-up CT scans; and (e) a potential for increased anxiety of both the patient and the physician about nonsignificant pathology. All of these limitations are balanced against a possibility that this could lead to an earlier detection of lung cancer with the consequent improvement in the chances of the patients' survival. Extensive studies of screening CT in older smokers have revealed the prevalence of cancer to be between 0.3 and 1%. However, when applied to an ambulatory population of patients presenting for an evaluation of angina, the prevalence of lung cancer or significant non-cardiac findings may be significantly lower. We have reviewed all the relevant literature and sought to determine the potential benefits and harms of specifically overreading CTA for non-cardiac pathology. The weight of the evidence suggests that it is most prudent to not specifically reconstruct and re-read CTA scans for lung nodules. If a non-cardiac abnormality is visualized by the primary interpreter of the cardiac CT, appropriate referral or follow-up is prudent.

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

PURPOSE

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSION

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

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

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

Attitudes towards screening for lung cancer among smokers and their non-smoking counterparts

BACKGROUND

There has been resurgence of interest in lung cancer screening using low-dose computed tomography. The implications of directing a screening programme at smokers has been little explored.

METHODS

A nationwide telephone survey was conducted. Demographics, certain clinical characteristics and attitudes about screening for lung cancer were ascertained. Responses of current, former and never smokers were compared.

RESULTS

2001 people from the US were interviewed. Smokers were significantly (p < 0.05) more likely than never smokers to be male, non-white, less educated, and to report poor health status or having had cancer, and less likely to be able to identify a usual source of healthcare. Compared with never smokers, current smokers were less likely to believe that early detection would result in a good chance of survival (p < 0.05). Smokers were less likely to be willing to consider computed tomography screening for lung cancer (71.2% (current smokers) v 87.6% (never smokers) odds ratio (OR) 0.48; 95% confidence interval (CI) 0.32 to 0.71). More never smokers as opposed to current smokers believed that the risk of disease (88% v 56%) and the accuracy of the test (92% v 71%) were important determinants in deciding whether to be screened (p < 0.05). Only half of the current smokers would opt for surgery for a screen-diagnosed cancer.

CONCLUSION

The findings suggest that there may be substantial obstacles to the successful implementation of a mass-screening programme for lung cancer that will target cigarette smokers.

Extended lung cancer incidence follow-up in the Mayo Lung Project and overdiagnosis

BACKGROUND

A troubling aspect of cancer screening is the potential for overdiagnosis, i.e., detection of disease that, in the absence of screening, would never have been diagnosed. Overdiagnosis is of particular concern in lung cancer screening because newer screening modalities can identify small nodules of unknown clinical significance. Previously published analyses of data from the Mayo Lung Project, a large randomized controlled trial conducted among 9211 male cigarette smokers in the 1970s and early 1980s indicated that overdiagnosis might exist in lung cancer screening. At the end of follow-up (July 1, 1983), no difference in lung cancer mortality was observed, but an excess of 46 cases in the intervention arm suggested overdiagnosis. Because that excess could instead have resulted from short follow-up time, we investigated this possibility by conducting long-term lung cancer incidence follow-up.

METHODS

We investigated the lung cancer status through 1999 of the 7118 participants in the Mayo Lung Project who were alive and without diagnosed lung cancer in 1983 by use of medical records, surveys mailed to participants or next-of-kin, and state death certificates.

RESULTS

Information was available for 6101 participants, including 811 with inconclusive lung cancer status. From November 1971 through December 31, 1999, 585 participants in the intervention arm and 500 in the usual-care arm were diagnosed with lung cancer.

CONCLUSIONS

The persistence of excess cases in the intervention arm after 16 additional years of follow-up provides continued support for overdiagnosis in lung cancer screening.

Early Detection of Lung Cancer

The overall 5-year survival of lung cancer is only 10% in Europe and 15% in the United States, and progress in curative treatments during the last 20 years has been modest. Late diagnosis of extensive disease is the main reason of failure. Early detection with low-dose spiral computed tomography (CT) is one of the most promising development of clinical research, and continuous improvements in technology can make this instrument more effective than mammography in breast cancer detection. In order to prove the benefit of early detection by reduction of lung cancer mortality, we need to enroll large numbers of high-risk individuals in multicentric prospective randomized trials combining primary prevention by smoking cessation with diagnostic intervention with low-dose spiral CT, optimal management of cancer and minimum damage for healthy individuals. Molecular biology research within early detection trials, combining genomic and proteomic analysis of blood and sputum, may improve the differential diagnosis, define the individual risk of cancer incidence and failure, and help target therapies on the basis of biologic profile.

Update in screening of lung cancer

In the USA, lung cancer is the leading cause of cancer death. Earlier studies of CXR and sputum cytology screening conducted in the 1970s showed no mortality benefit. Accordingly, mass screening for lung cancer was abandoned and is not currently recommended. Recently, interest in lung cancer screening has been revived due to various reports showing an advantage of low-dose CT over CXR in detecting smaller size tumours and at an earlier stage. Although these reports generated much enthusiasm for screening among clinicians and the general public, the effectiveness of low-dose CT in reducing lung cancer-specific mortality rates has not been demonstrated. Large-scale randomized controlled trials are currently in progress to determine the efficacy of CXR and low-dose CT screening. This review highlights the advantages and limitations of current modalities for lung cancer screening. The cases for and against screening with currently available modalities are examined. Additional new screening modalities are also discussed.

Screening for cancer: are resources being used wisely?

Cancer screening is commonly offered in order to detect tumors at an early, treatable stage. These efforts are highly advocated and widely accepted by the general public. However, there is conflicting evidence about the benefits of screening for breast cancer in pre-menopausal women, prostate cancer in older men, and colorectal cancer for both sexes. This paper examines cancer screening in relation to a disease reservoir hypothesis. There is a reservoir of undetected disease that can be found with more aggressive screening. However, much of the disease that is detected may be classified as pseudodisease because it will have no effect of life expectancy or health-related quality of life. Pseudodisease is defined as detectable disease that will never be clinically significant. A second concern about screening is that randomized clinical trials often show benefits of cancer screening for disease-specific endpoints but no benefit for total mortality. Further, screening for some cancers may significantly increase healthcare costs without enhancing population health status. Improvements in biomarkers and in screening methodologies will significantly increase the number of cancers detected. Future research is necessary in order to determine which population-based screening programs are the best use of public health resources.

Baseline chest radiograph for lung cancer detection in the randomized Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial

BACKGROUND

The Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial was initiated in 1992 to examine cause-specific mortality reduction from screening for these four cancers in men and women. We report lung cancer detection results of the baseline screening round.

METHODS

Of the 154,942 participants enrolled, who were aged 55-74 years with no history of PLCO cancers, 77,465 were randomly assigned to the intervention arm. Current or former smokers and never smokers in this arm received an initial single-view posterior-anterior chest radiograph.

RESULTS

In the initial screen, 5991 (8.9%, 95% confidence interval [CI] = 8.7% to 9.2%) of radiographs were suspicious for lung cancer: 8.2% (95% CI = 7.9% to 8.5%) for women and 9.6% (95% CI = 9.3% to 10.0%) for men. Rates were highest for older age groups and for smokers. Among those 5991 participants with a positive screen, 206 (3.4%, 95% CI = 3.0% to 3.9%) underwent biopsy examination, 126 (61.2%, 95% CI = 54.5% to 67.8%) of whom were diagnosed with lung cancer within 12 months of the screen (59 in women and 67 in men). The positive predictive value was 2.1% (95% CI = 1.7% to 2.5%), and 1.9 lung cancers were detected per 1000 screens. Among these cancers, 44% (95% CI = 35% to 52%) were stage I non-small-cell lung cancer. High rates of lung cancer were found in current smokers (6.3 per 1000 screens) and in former smokers who had smoked within the past 15 years (4.9 per 1000 screens). The lung cancer detection rate among never smokers was 0.4 per 1000 screens; this group accounted for 11% (95% CI = 5.6% to 16.6%) of the cancers identified.

CONCLUSIONS

In the baseline screen, nearly half the cancers were stage I. Whether this experience results in a reduction in lung cancer mortality is yet to be seen.

Screening for lung cancer: New horizons?

Lung cancer remains the leading cause of cancer-related deaths in the world. At present, the only high rate of cure therapy is surgical resection at early stage of disease. Early detection could potentially decrease lung cancer mortality suggesting that this cancer should be a good candidate for screening. Results of trials involving chest X-ray, sputum cytology and low-dose computed tomography (CT) are discussed here. The latter tool offers advantages over chest X-ray, but final results from controlled well conducted trials are necessary before the real utility of CT mass screening can be determined. Further approaches to secondary prevention such as screening with positron emission tomography (PET), autofluorescence bronchoscopy and biomarkers hold great promise for the future.

Analysis of Mortality Data From Cancer Screening Studies

BACKGROUND

Appropriate statistical analysis is required to measure the impact of early detection and treatment of cancer. The current practice of using cumulative mortality ignores both (1) the delay between early treatment and the time that any averted deaths would have otherwise occurred, and (2) cessation of these delayed benefits some time after screening is discontinued.

METHODS

We use time-specific mortality density ratios to estimate the mortality ratio in the "window of influence." We then use time-specific incidence density ratios to assess the extent to which the removal of polyps and other possibly precancerous lesions detected by fecal occult blood screening reduces the incidence of colorectal cancer.

RESULTS

Applied to a theoretical example, the current practice of using cumulative mortality substantially underestimates the reduction in mortality achievable by early treatment. If there is sufficient time for the full impact to emerge, time-specific mortality patterns provide a more accurate measure. In a previous analysis of the screening study, the reduction in cumulative incidence in the screened groups was just under 20%. In our reanalysis, yearly incidence density ratios indicate that had screening not been interrupted, there might have been a 40% reduction in incidence.

CONCLUSIONS

Time-specific mortality ratios provide a more sensitive measure of the effects of early detection and treatment. Measures based on cumulative mortality are diluted by inclusion of deaths that occur soon after the initiation of screening as well as deaths that occur too long after the cessation of screening.

Lung cancer screening

PURPOSE OF REVIEW

Advances in imaging technologies and biomarker research offer hope that the incidence and mortality of lung cancer can be reduced by screening similar to what have been achieved for cancer of the cervix, breast, and colon.

RECENT FINDINGS

Spiral computed tomography with multitrack scanners and autofluorescence bronchoscopy offer unprecedented sensitivity to detect lung cancer even during the preinvasive stage. The high sensitivity of these tests, however, is associated with a low specificity. Better selection of individuals at highest risk of lung cancer using biomarkers in sputum, blood, or exhaled breath, as well as a better understanding of genetic susceptibility, may improve their positive predictive values, minimize unnecessary downstream investigations or treatment, as well as reduce screening costs.

SUMMARY

Improvement in the performance of sputum, exhaled breath, or blood biomarkers holds promise as the first screening step to identify individuals at highest risk of lung cancer beyond what age and smoking could predict to select those who would obtain the most benefits from spiral computed tomography or autofluorescence bronchoscopy as localization tools.

One Hundred Years of Lung Cancer

A hundred years ago, lung cancer was a reportable disease, and it is now the commonest cause of death from cancer in both men and women in the developed world, and before long, will reach that level in the developing world as well. The disease has no particular symptoms or signs for its detection at an early stage. Most patients therefore present with advanced stage IIIB or IV disease. Screening tests began in the 1950s with annual chest x-ray films and sputum cytology but they resulted in no improvement in overall mortality compared with control subjects. The same question is now being asked of spiral low-dose computed tomographic scanning. There have been big refinements in the staging classification of lung cancer and advances in stage identification using minimally invasive technology. Postsurgical mortality has declined from the early days of the 1950s but 5-year cure rates have only barely improved. The addition of chemotherapy to radical radiotherapy, together with novel radiotherapy techniques, is gradually improving the outcome for locally advanced, inoperable non-small cell lung cancer. Chemotherapy offers modest survival improvement for patients with non-small cell lung cancer, the modern agents being better tolerated resulting in an improved quality of life. The management of small cell lung cancer, which appeared so promising at the beginning of the 1970s, has hit a plateau with very little advance in outcome over the last 15 years. The most important and cost-effective management for lung cancer is smoking cessation, but for those with the disease, novel agents and treatment approaches are urgently needed.

Estimating the growth rates of primary lung tumours from samples with missing measurements

A method to estimate the population variability in tumour growth rate using incomplete data was developed. We assume exponential growth and lognormal distribution for the parameter of the growth curve. Estimates of growth rate obtained based on the cases with two measurements, one of which is obtained retrospectively, are biased towards lower growth rate. For the data sets where two measurements are available for some tumours and only one measurement for others (which means that no tumour was seen in retrospect for those cases), several approaches were developed that can eliminate or substantially reduce the bias. The relative error of the best estimates, as assessed by simulation, rarely exceeds 20 per cent. We found that the results of application of our estimation procedures to chest X-ray screening data agree well with the expectations.

Clinical Issues in the Management of Early Lung Cancer

Lung cancer is commonly diagnosed after metastatic spread, when therapies are rarely curative, providing an impetus for continued research directed at exploring approaches for cost-effective early lung cancer detection. Recently published pilot studies across three continents support a benefit of spiral computed tomography (CT) in detecting earlier stage non-small cell lung cancer. Improved resolution of early lung cancer is a result of significant changes in CT imaging hardware and software. The status and implications of these developments are reviewed. Many aspects of the management of screening for early lung cancer could be informed by optimizing the downstream clinical management of potential lung cancers identified by CT screening. The first and most critical issue is whether or not this improved detection rate is clearly associated with a reduction in lung cancer-related mortality. However, other related issues such as cost-benefit evaluations are also considered. If smaller, truly localized primary cancer can be routinely detected, then options for less morbid interventions would also be desirable. The rapid improvement in resolution and cost of spiral CT has provided a powerful impetus to reconsider the possibilities for achieving safe, economical, and meaningful early lung cancer detection.

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

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

[Non-small cell bronchogenic cancer in stage IA: mortality patterns after surgery]

OBJECTIVE

To determine the causes of death in patients treated surgically for nonsmall cell lung cancer (NSCLC) in stage IA and to evaluate the impact on survival of not performing systematic lymph node dissection and of the number of nodes resected.

PATIENTS AND METHODS

The study sample consisted of 156 patients operated on for NSCLC and classified in stage IA according to TNM staging. Only palpable or visible lymph nodes were dissected. Kaplan-Meier survival curves were compared using a log-rank test.

RESULTS

At the end of the study, 85 (54.5%) patients had died, 67 (42.9%) were alive, and 4 (2.5%) were lost to follow up. Twenty-three (14.7%) died from a recurrence of NSCLC: 2 with local tumors (1.2%), 2 with mediastinal node involvement (1.2%), and 19 (12.1%) with distant metastasis. The cause of death was unrelated to NSCLC in 62 (39.7%) cases: 33 (21.1%) had a new tumor, 18 of which were bronchogenic, and 29 (18.5%) had nonmalignant disease. The 5-year survival rate was 81.4%. The rate was 88.9% among patients from whom no lymph nodes were excised and 79.9% among those with node excision, although the difference was not statistically significant (P=.4073).

CONCLUSIONS

Our experience suggests that neither the fact of not performing systematic lymph node dissection nor the number of nodes resected has an impact on survival. A substantial number of patients died of causes unrelated to the NSCLC for which they had been treated.

Oblique approach of computed tomography guided needle biopsy using multiplanar reconstruction image by multidetector-row CT in lung cancer

The purpose of this study was to establish the technique of multiplanar reconstruction (MPR) with multidetector-row (MDR) computed tomography (CT) guided needle biopsy for the diagnosis to access very difficult lesions. The CT guided percutaneous biopsy are well-established methods to obtain cytological and histological material such as the peripheral tumors in lung cancer. Occasionally, the conventional CT cannot permit planning a trajectory to avoid passage through bones, avoidance of bullae, fissures or vessels. In addition, some lesions are situated in less favorable locations such as those in the costophrenic recess or close to the mediastinum. Rarely can we diagnose them. MPR with MDR-CT has recently become widely available with applications for thoracic lesions. MPR images have been used to evaluate the location of small peripheral lung nodules to the relation of bullaes, vessels, and costophrenic recess. To diagnose these lesions, the usefulness of MPR were evaluated for an planning of an oblique approach of CT guided needle biopsy. MPR images were reconstructed as a line from the needle entry point to the target lesion. The first oblique image applied as the direction of posterior-anterior and cranio-caudal axis, and the second oblique image applied as the direction of posterior-anterior and left-right. Eleven out of 151 patients were required MPR technique to allow possible access to target, because of avoidance of bone and fissures in the needle pass or located in the costophrenic recess, between April 2001 and December 2002. The 5/11 patients were at the upper site (segment 1, 2 and 6) behind the scapula and ribs, 3/11 patients were at the lower lobe (segment 10) in the costophrenic recess, and 3/11 were middle lobe or segment 3 covered by the ribs and fissures. All the lesions except one were histologically diagnosed. Five patients were adenocarcinoma, and the other five patients were benign tumors. Pneumothorax occurred in one patient before we obtained the specimens. MPR guided needle biopsy with oblique approach was thought to be useful for diagnosis of very difficult thoracic lesions and would obviate an unnecessary surgical thoracoscopy.

Screening for Non-Small Cell Lung Cancer

Lung cancer is the leading cause of cancer mortality and is usually discovered at an advanced stage, when treatment is generally not effective. Many researchers have investigated the value of screening for lung cancer, which would theoretically allow earlier detection and more effective treatment. Unfortunately, no trials of screening strategies for lung cancer have shown a mortality benefit, and as a result, no major medical organization currently recommends screening. Research continues to seek proof of the benefit of screening as new techniques are developed, including low-dose spiral computed tomography (CT), autofluorescence bronchoscopy, and advanced techniques of sputum analysis. Although there are promising data on the sensitivity of these newer screening methods, especially low-dose CT, for detecting early lung cancer, none of the published trials are controlled, and they have not yet proven a decrease in mortality. There are ongoing randomized, controlled trials aiming to demonstrate a mortality benefit. Patients who are interested in being screened for lung cancer should be encouraged to participate in well-designed clinical trials whenever possible.

CT Screening for Lung Cancer: Past and Ongoing Studies

It has been widely recognized that the oft-quoted randomized clinical trials (RCTs) of lung cancer screening by chest radiography--studies that were interpreted as showing no benefit--were seriously flawed. We begin by describing the shortcomings of these trials and presenting an analysis of the problems typically encountered in performing RCTs in this area. Screening for lung cancer using computed tomography (CT) has shown that CT offers great superiority over chest radiography in diagnosing small lung cancers in the three studies that performed both CT and chest radiography on all patients. The Early Lung Cancer Action Project (ELCAP), showed that false-positive results can be kept reasonably low and are much less common on repeat screening, and that CT screening can be managed with no notable excess of percutaneous or surgical biopsies when following a well-defined regimen of screening. This regimen details the parameters of the initial CT, the definition of a positive result, and the subsequent work-up of positive results. Following the updated International (I)-ELCAP protocol, it has been further found that (1) the frequency of positive results is low: 15% for the baseline cycle of screening and 6% for the subsequent cycles. (2) The frequency of screen-diagnoses as compared with all diagnoses is 97% or higher. (3) The relative frequency of presurgical Stage I is well over 80%; the median diameter of the screen-diagnosed cases on repeat screening is 8 mm (versus 15 mm at baseline screening). (4) A high percentage of the screen-diagnosed cases were genuine cancers which led to death if not treated. (5) The estimated 8-year cure rate for resected baseline screen-diagnosed lung cancers without evidence of lymph node metastases is 95% and for resected annual repeat cancers is 98%. (6) CT screening appears to be highly cost-effective. These preliminary results of CT screening suggests that the cure rate of screen-diagnosed lung cancer, using the I-ELCAP regimen of screening, may be over 70% as compared with that of usual care of 10% and that of chest radiographic screening of 20%.

Lung Cancer Screening

It has been demonstrated that 85% of all lung cancers are associated with previous or current smoking. A group of patients has been identified that is at a higher risk for lung cancer, stroke, and heart disease. This article reviews previous reports, current consensus statements, problems that are associated with current screening programs, and hopes for the future.

CT screening for lung cancer: five-year prospective experience

PURPOSE

To report results of a 5-year prospective low-dose helical chest computed tomographic (CT) study of a cohort at high risk for lung cancer.

MATERIALS AND METHODS

After informed written consent was obtained, 1520 individuals were enrolled. Protocol was approved by institutional review board and National Cancer Institute and was compliant with Health Insurance Portability and Accountability Act, or HIPAA. Participants were aged 50 years and older and had smoked for more than 20 pack-years. Participants underwent five annual (one initial and four subsequent) CT examinations. A significant downward shift was evaluated in non-small cell lung cancers detected initially from advanced stage down to stage I by using a one-sided binomial test of proportions. Poisson regression and Fisher exact tests were used for comparisons with Mayo Lung Project.

RESULTS

In 788 (52%) men and 732 (48%) women, 61% (927 of 1520) were current smokers, and 39% were former smokers. After five annual CT examinations, 3356 uncalcified lung nodules were identified in 1118 (74%) participants. Sixty-eight lung cancers were diagnosed (31 initial, 34 subsequent, three interval cancers) in 66 participants. Twenty-eight subsequent cases of non-small cell cancers were detected, of which 17 (61%; 95% confidence interval: 41%, 79%) were stage I tumors. Diameter of cancers detected subsequently was 5-50 mm (mean, 14.4 mm; median, 10.0 mm). Analysis for a more than 50% shift in proportion of stage I non-small cell cancer detection did not show statistical significance. Forty-eight participants died of various causes since enrollment. Lung cancer mortality rate for incidence portion of trial was 1.6 per 1000 person-years. There was no significant difference in lung cancer mortality rates of cancers detected in subsequent examinations between this trial and Mayo Lung Project after separation of participants into subsets (2.8 vs 2.0 per 1000 person-years, P = .43).

CONCLUSION

CT allows detection of early-stage lung cancers. Benign nodule detection rate is high. Results suggest no stage shift.

Identification of Epigenetic Aberrant Promoter Methylation in Serum DNA Is Useful for Early Detection of Lung Cancer

Purpose: The purpose of this study is to evaluate the usefulness of serum DNA methylation of five tumor suppressor genes for early detection of lung cancer.

Experimental Design: Methylation status in serum DNA from 200 patients undergoing bronchofiberscopic examination for abnormal findings on chest radiograph detected by lung cancer screening or surveillance was examined using methylation-specific PCR.

Results: Ninety-one patients were given a pathologic diagnosis of lung cancer, 9 other malignant diseases, and 100 nonmalignant pulmonary diseases. In patients with lung cancer, methylation was detected in 18.7% for MGMT, 15.4% for p16INK4a, 12.1% for RASSF1A, 11.0% for DAPK, and 6.6% for RAR-β, which was higher compared with that in patients with nonmalignant diseases. Age and smoking status seemed to associate with methylation status. Sensitivity, specificity, and predictive value of methylation in at least one gene for diagnosis of lung cancer were 49.5%, 85.0%, and 75.0%, respectively. Adjusted odds ratio (95% confidence interval) for having lung cancer was 5.28 (2.39-11.7) for patients with methylation in one gene and 5.89 (1.53-22.7) for those with methylation in two or more genes. It is of note that methylation was identified in 50.9% of stage I lung cancer patients, whereas serum protein tumor markers were positive in 11.3% of them.

Conclusions: These results suggest that identification of promoter methylation of tumor suppressor genes in serum DNA could be useful for early detection of lung cancer.

Cancer Screening in Theory and in Practice

Improvements in technology have led to a number of tests that can be used to suggest that a patient has a cancer. Advances in cancer biology and medical imaging have led to a number of cancer screening tests. Cancer screening is commonly advocated, but its complexity is often lost in guidelines that have sound-bite quality. It is commonly viewed as of no harm, when in fact there are harms associated with every known screening test. Indeed, many screening experts believe a screening test should only be used when the potential for benefit clearly outweighs the potential for harm.

Cancer screening principles are classically within the realm of the epidemiologist. As more screening tests are developed, these principles have become more relevant to the practicing clinician. What is known and what is unknown about screening is distinctly different from what is believed by the public and many practicing clinicians.

Many tests have both screening and diagnostic uses, and it is only the context in which these are used that determines whether they are screening or diagnostic. A screening test is done on asymptomatic individuals who receive the test principally because they are of the age or sex at risk for the cancer. A diagnostic test is done on an individual because of clinical suspicion of disease.

Bayesian models for population-based case-control studies when the population is in Hardy-Weinberg equilibrium

Association analysis of genetic polymorphisms has been mostly performed in a case-control setting with unrelated affected subjects compared with unrelated unaffected subjects. In this paper, we present a Bayesian method for analyzing such case-control data when the population is in Hardy-Weinberg equilibrium. Our Bayesian method depends on the informative prior which is the retrospective likelihood based on historical data, raised to a power a. By modeling the retrospective likelihood properly, different prior information about the studied population can be incorporated into the specification of the prior. The scalar a is a precision parameter quantifying the heterogeneity between current and historical data. A guide value for a is discussed in this paper. The informative prior and posterior distributions are proper under very general conditions. Therefore, our method can be applied in most case-control studies. Further, for assessing gene-environment interactions, our approach will naturally lead to a Bayesian model depending only on the case data, when genotype and environmental factors are independent in the population. Thus our approach can be applied to case-only studies. A real example is used to show the applications of our method.

The science of early detection

Most clinical judgment and clinical intuition derives from observations made on patients who suffer from a disease or medical condition. However, the target population for cancer screening is healthy people who would not seek out a health professional unless convinced to do so by advertising or public messages. Extrapolation of clinical observations to the target population for screening can be very misleading and even harmful. This is because powerful screening biases and confounding effects--such as selection bias, lead-time bias, length-bias sampling, and overdiagnosis--can mislead even the most astute clinician. This article will discuss those biases, review methods to avoid them, and provide useful resources to the clinician or health scientist.

What is early lung cancer? A review of the literature

The dismal cure rate of patients with lung cancer and the stage shift hypothesis have propelled the interest to perform screening at large, despite that previous randomized clinical trials failed to show any mortality benefit and the controversial issue of overdiagnosis. Due to early detection programs, a larger number of individuals at risk will be found to harbor small and potentially malignant early stage lesions. The application of non- and minimal invasive techniques for early detection, staging and treatment will become increasingly important. This review deals with the available clinical, surgical and pathological data focusing on early lung cancer lesions < or =1 cm. Literature data from both centrally located and parenchymal lesions < or =3 cm. have been analyzed. For all sub-centimeter lesions, minimal invasive staging and treatment approaches must still be considered inappropriate. Less invasive and less extensive treatment methods may be considered in high risk individuals with < or =1 cm. peripheral lesion showing > or =50 ground glass opacity on high resolution CT scan and those with superficial lesion in their central airways without deeper tumor invasion in the bronchial wall. Caution is necessary, however, as clinical staging remains inferior to pathological staging which is based on tissue samples collected after complete tumor removal and mediastinal lymph nodes dissection have been performed.

Routine Chest Radiography in a Primary Care Setting

PURPOSE

To determine the frequency, diagnostic yield, outcomes, cost, and rate of false-positive results of routine chest radiography performed in asymptomatic patients in the primary care setting.

MATERIALS AND METHODS

Radiography reports on all patients who underwent routine or screening posteroanterior and lateral chest radiography at a university-affiliated primary care clinic in 2001 were reviewed. Radiographic results were coded as normal or minor findings or as major abnormalities, such as pulmonary nodules, requiring further diagnostic evaluation. Outcomes of patients with major abnormalities were established by using chart reviews or reviewing additional radiographs. Costs were estimated by using 2002 Medicare reimbursement rates. The main measures assessed were frequency, costs, and rate of false-positive results of routine chest radiography.

RESULTS

Of 3812 radiographs obtained at the primary care clinic, 1282 (34%) were ordered for routine or screening purposes by the referring physician. Nine hundred twenty-two radiographs were obtained in male patients and 360 were obtained in female patients; their mean and median age was 49 years (age range, 4-87 years). Fifteen chest radiographs showed major abnormalities. No patient younger than 40 years had a major abnormality. Fourteen of the 15 findings of major abnormalities proved to be false-positive. No disease requiring treatment was diagnosed as a result of radiographic findings. The total cost for follow-up radiography and computed tomography was US dollar 46,609.49.

CONCLUSION

Routine chest radiography has low diagnostic yield in asymptomatic primary care patients.

Molecular oncology — perspectives in lung cancer

Despite novel therapies in lung cancer treatment the 5-year survival rate still remains poor. Furthermore, screening concepts for early diagnosis, based on conventional sputum cytology and chest radiography, have so far not demonstrated an impact on decreasing lung-cancer mortality. More specific molecular markers allow new insights in the process of lung carcinogenesis. Furthermore they raise the hope that they provide new tools for early diagnosis and screening of high-risk individuals, determination of prognosis, and identification of innovative treatments. In this review, these perspectives of molecular targets in lung cancer will be discussed and summarised. Angiogenesis-stimulating factors (VEGF, FGF, MMP, etc.), parameters concerning tumour cell proliferation and apoptosis (EGFR, p53, K-ras, rb, bcl-2, etc.) are well known. Several of these genetic factors have already been investigated, but no single parameter has yet gained a sufficient selectivity regarding prognostic significance or therapeutic efficacy. New aspects in the complex tumour-stroma interaction and the interactive, cross-talking signal transduction pathways and recently developed functional genomic approaches, such as DNA microarrays and proteomics might lead to further progress in biological staging models and treatment concepts.