The efficacy of lung cancer screening conducted in 1990s: four case-control studies in Japan

The consecutive impact of COVID-19 on thoracic surgical procedures in Japan: an analysis of data from the National Clinical Database

PURPOSE

The current study was designed to analyze the impact of the COVID-19 pandemic on general thoracic surgeries in Japan.

METHODS

Changes in surgeries for lung cancer and metastatic lung tumors were evaluated based on National Clinical Database data regarding cancer screening.

RESULTS

In 2021, surgeries for primary lung cancer increased by 3.4% compared to 2020, which, given the increase from 2014 to 2019, indicates an overall 11.1% decrease. In contrast, surgeries for metastatic lung tumors in 2021 decreased by 5.8% compared to 2020, which, given the increase from 2014 to 2020, indicates an overall 9.2% decrease. Half of the primary diseases for metastatic lung tumor were cases of colorectal cancer. Low anterior resection procedures in 2020 decreased by 5.5% compared to 2019. Lung and colon cancer screening examinees in 2021 were increased compared to 2020; however, they still showed respective decreases of 11% and 9.0% compared to 2019.

CONCLUSIONS

Surgeries for primary lung cancer still decreased substantially during the COVID-19 pandemic. The continued stagnation of screening was responsible for this decrease. Surgeries for metastatic lung tumors decreased profoundly, and the decrease in screening for primary tumors was responsible for this reduction. Our findings emphasize the significance of maintaining cancer screening efforts, even during a pandemic.

Asian Perspective on Lung Cancer Screening

Lung cancer is the leading cause of cancer-related mortality in Japan and worldwide. Early detection of lung cancer is an important strategy for decreasing mortality. Advances in diagnostic imaging have made it possible to detect lung cancer at an early stage in medical practice. Conversely, screening of asymptomatic healthy populations is recommended only when the evidence shows the benefits of regular intervention. Due to a variety of evidence and racial differences, screening methods vary from country to country. This article focused on the perspective of lung cancer screening in Japan.

Epidemiological and therapeutic profiles of lung cancer patients in the Hokushin Region Japan: a retrospective hospital administrative database study

OBJECTIVE

This study was performed to validate the epidemiology, initial treatment, and clinical practice of lung cancer patients in the Hokushin region, Japan.

METHODS

We retrospectively surveyed data of 5503 newly diagnosed and registered lung cancer patients in 22 principal hospital-based cancer registries in Hokushin region linked with health insurance claims data for registered patients between 2016 and 2017.

RESULTS

The patients consisted of 3677 (66.8%) men and 1826 (33.2%) women with a mean (range) age of 72.2 (27-103) years). Diagnoses were small cell lung cancer (n = 512, 9.4%), squamous cell carcinoma (n = 1083, 19.7%), and non-squamous non-small cell lung cancer (NSCLC; n = 3906, 70.9%). The population with stage I disease in Toyama prefecture (41.1%) was smaller than in the other three prefectures associated with reduced selection of initial surgical therapy and increased frequencies of stage IV disease (33.2%) and best supportive care (18.6%). Initial chemotherapy for stage IV non-squamous NSCLC consisted of tyrosine kinase inhibitors in 39.3% of cases for EGFR and 4% of cases for ALK-positive non-squamous NSCLC, followed by platinum compounds (25.9%) non-platinum compounds (12.9%), and immune checkpoint inhibitors (10.2%). Carboplatin was the commonly prescribed first-line cytotoxic chemotherapeutic agent (65.4% of patients under 75 years and in 96.7% of patients over 75 years).

CONCLUSION

This study revealed real-world data on epidemiological and treatment status in lung cancer in four prefectures in Hokushin region, Japan. Simultaneous analysis of nationwide registry and insurance data could provide valuable insights for the development of lung cancer screening and medical treatment strategies. In addition, the comparative data analysis with other lesions or countries will be useful for evaluating the differences in clinical practice of cancer managements.

A Review of Deep Learning Techniques for Lung Cancer Screening and Diagnosis Based on CT Images

One of the most common and deadly diseases in the world is lung cancer. Only early identification of lung cancer can increase a patient's probability of survival. A frequently used modality for the screening and diagnosis of lung cancer is computed tomography (CT) imaging, which provides a detailed scan of the lung. In line with the advancement of computer-assisted systems, deep learning techniques have been extensively explored to help in interpreting the CT images for lung cancer identification. Hence, the goal of this review is to provide a detailed review of the deep learning techniques that were developed for screening and diagnosing lung cancer. This review covers an overview of deep learning (DL) techniques, the suggested DL techniques for lung cancer applications, and the novelties of the reviewed methods. This review focuses on two main methodologies of deep learning in screening and diagnosing lung cancer, which are classification and segmentation methodologies. The advantages and shortcomings of current deep learning models will also be discussed. The resultant analysis demonstrates that there is a significant potential for deep learning methods to provide precise and effective computer-assisted lung cancer screening and diagnosis using CT scans. At the end of this review, a list of potential future works regarding improving the application of deep learning is provided to spearhead the advancement of computer-assisted lung cancer diagnosis systems.

The impact of COVID-19 on thoracic surgical procedures in Japan: analysis of data from the National Clinical Database

Objective

The COVID-19 pandemic has far-reaching collateral health impacts on the ongoing delivery of surgical care worldwide. The current study was designed to analyze the impact of the COVID-19 pandemic on the number of surgeries of general thoracic surgery in Japan.

Methods

Changes in the number of surgeries for total and three representative tumors were analyzed using the National Clinical Database data with reference to the pandemic infection rate and lung cancer screening.

Results

In 2020, the number of surgeries in total and for primary lung cancer and mediastinal lung tumor decreased by 4.9, 5.1, and 5.0 %, respectively. Considering the five-year trend towards a 5 % annual increase, there was a potential 10 % decrease in the number of primary lung cancer surgeries. The number of primary lung cancer surgeries bottomed in July 2020 but recovered towards the end of the year. In contrast, the number of metastatic lung tumor surgeries in 2020 increased by 3.2 %, following a similar trend observed over the previous five years. The number of lung cancer screening examinees decreased markedly with the lowest number in May. Our findings indicate that surgical triage had a limited impact on the decrease in primary lung cancer surgeries during the pandemic; rather, the decrease in lung cancer screening, which was a few months preceding, is most likely responsible.

Conclusions

The decrease in primary lung cancer was mainly caused by the decrease in lung cancer screening, indicating that continuing screening is vital even during a pandemic.

Deep learning-based algorithm for lung cancer detection on chest radiographs using the segmentation method

We developed and validated a deep learning (DL)-based model using the segmentation method and assessed its ability to detect lung cancer on chest radiographs. Chest radiographs for use as a training dataset and a test dataset were collected separately from January 2006 to June 2018 at our hospital. The training dataset was used to train and validate the DL-based model with five-fold cross-validation. The model sensitivity and mean false positive indications per image (mFPI) were assessed with the independent test dataset. The training dataset included 629 radiographs with 652 nodules/masses and the test dataset included 151 radiographs with 159 nodules/masses. The DL-based model had a sensitivity of 0.73 with 0.13 mFPI in the test dataset. Sensitivity was lower in lung cancers that overlapped with blind spots such as pulmonary apices, pulmonary hila, chest wall, heart, and sub-diaphragmatic space (0.50–0.64) compared with those in non-overlapped locations (0.87). The dice coefficient for the 159 malignant lesions was on average 0.52. The DL-based model was able to detect lung cancers on chest radiographs, with low mFPI.

Low-dose CT lung cancer screening in never-smokers and smokers: results of an eight-year observational study

Background

This was an observational study of Japanese participants who underwent low-dose computed tomographic (LDCT) lung cancer screening between February 2004 and March 2012, to evaluate the lung cancers in never-smokers and smokers.

Methods

The study population consisted of a total of 12,114 subjects [never-smokers, 6,021 (49.70%); smokers with <30 pack-years of smoking, 3,785 (31.24%); smokers with ≥30 pack-years of smoking, 2,305 (19.03%); unknown smoking status, 3 (0.02%)]. The odds ratio (OR) of lung cancer detection according to the smoking status adjusted for age and gender was evaluated.

Results

A total of 152 lung cancers were diagnosed in 133 patients [never-smokers, 66 (49.6%); smokers with <30 pack-years of smoking, 31 (23.3%); smokers with ≥30 pack-years of smoking, 36 (27.1%)]; therefore, 72.9% of lung cancer patients did not meet the National Lung Screening Trial (NLST) criterion of smokers with ≥30 pack-years of smoking. The OR of lung cancer detection in smokers with ≥30 pack-years of smoking was higher than that in the never-smokers (OR =1.71, 95% CI: 1.04-2.82, P=0.03) and that in smokers with <30 pack-years of smoking (OR =1.71, 95% CI: 1.04-2.80, P=0.03), while the OR of lung cancer detection in smokers with <30 pack-years of smoking was the same as that in the never-smokers (OR =1.00, 95% CI: 0.62-1.61, P=0.99).

Conclusions

Although the OR of lung cancer detection in smokers with ≥30 pack-years of smoking was higher than that in the never-smokers and smokers with <30 pack-years of smoking, approximately 70% of lung cancer patients might be missed if we only adopted the NLST criterion of smokers with ≥30 pack-years of smoking. Therefore, never-smokers and smokers with <30 pack-years of smoking should be included in the target population for LDCT lung cancer screening in Japan.

A simulation study of the effect of lung cancer screening in China, Japan, Singapore, and South Korea

More than 50% of the world's lung cancer cases occur in Asia and more than 20% of cancer deaths in Asia are attributable to lung cancer. The U.S. National Lung Screening Trial has shown that lung cancer screening with computed tomography (CT) can reduce lung cancer deaths. Using the Lung Cancer Policy Model-Asia (LCPM-Asia), we estimated the potential mortality reduction achievable through the implementation of CT-based lung cancer screening in China, Japan, Singapore, and South Korea. The LCPM-Asia was calibrated to the smoking prevalence of each of the aforementioned countries based on published national surveys and to lung cancer mortality rates from the World Health Organization. The calibrated LCPM-Asia was then used to simulate lung cancer deaths under screening and no-screening scenarios for the four countries. Using screening eligibility criteria recommended by the U.S. Centers for Medicare & Medicaid Services (CMS), which are based on age and smoking history, we estimated the lung cancer mortality reduction from screening through year 2040. By 2040, lung cancer screening would result in 91,362 life-years gained and 4.74% mortality reduction in South Korea; 290,325 life-years gained and 4.33% mortality reduction in Japan; 3,014,215 life-years gained and 4.22% mortality reduction in China; and 8,118 life-years gained and 3.76% mortality reduction in Singapore. As for mortality reduction by smoker type, current smokers would have the greatest mortality reduction in each country, ranging from 5.56% in Japan to 6.86% in Singapore. Among the four countries, lung cancer screening under CMS eligibility criteria was most effective in South Korea and least effective in Singapore. Singapore's low smoking prevalence and South Korea's aging population and higher smoking prevalence may partially explain the discrepancy in effectiveness. CT screening was shown to be promising as a means of reducing lung cancer mortality in the four countries.

A population-based cohort study to evaluate the effectiveness of lung cancer screening using low-dose CT in Hitachi city, Japan

Objectives

To evaluate the effectiveness of lung cancer screening using low-dose computed tomography for the general population, we conducted a retrospective cohort study of screening for participants among Hitachi residents.

Materials and Methods

Citizens aged 50-74 who underwent low-dose computed tomography screening at least once during 1998-2006 were defined as the computed tomography group, and those who underwent X-ray screening at least once during the same period, but did not receive low-dose computed tomography screening throughout the follow-up period, were defined as the XP group. We investigated the lung cancer incidence rate, mortality rate and all-cause mortality rate for both groups from the first lung cancer screening to the end of 2012.

Results

In the computed tomography group (17 935 residents; 9790 males and 8145 females), 273 cases of lung cancer (1.5%), 72 cases of lung cancer death (0.4%), and 885 cases of all-cause death (4.9%) were observed. On the other hand, 164 cases (1.1%) of lung cancer, 80 cases (0.5%) of lung cancer death and 1188 cases (7.6%) of all-cause death were observed in the XP group (15 548 residents; 6526 males and 9022 females). The hazard ratios of the computed tomography group to the XP group adjusted for gender, age and smoking history were 1.23 for lung cancer incidence rate, 0.49 for lung cancer mortality rate and 0.57 for all-cause mortality rate. Non-smokers and light smokers (<30 pack-years) had a significantly lower lung cancer mortality (0.41 and 0.21, respectively).

Conclusion

low-dose computed tomography screening for a population including non-smokers and light smokers may be effective.

Chest radiography surveillance for lung cancer: Results from a National Health Insurance database in South Korea

BACKGROUND

Lung cancer screening with low-dose computed tomography reduced mortality in selected high risk patients. However, the use of chest radiography for lung cancer screening in Asian populations is still controversial. We investigated the effectiveness of chest radiographic surveillance using a nationwide health service data in South Korea.

METHODS

Data from the Korean National Health Insurance Service examinee cohort of 2004 to 2013 were examined, and 63,228 patients with lung cancer were identified, 38,494 (57%) of whom underwent chest radiography screening. The others did not undergo lung cancer screening and were considered as a control group. Clinical data including age, smoking, screening intervals, lung cancer stages, treatments, and survival were collected. Survival gain from surveillance after adjustment for lead-time bias based on the sojourn time was calculated. Cox-proportional hazard analyses were performed to evaluate the effectiveness of screening and to determine the appropriate screening interval for chest radiography surveillance.

RESULTS

Early lung cancer was found in 38% of patients receiving chest radiography versus 26% of those without surveillance. A patient age of more than 65 years (hazard ratio [HR], 1.53; 95% confidence limits [CL], 1.50-1.56), male (HR, 1.66; 95% CL, 1.62-1.70), and high lung cancer stages at the time of diagnosis were independent factors associated with mortality (each, P < 0.001). Chest radiography surveillance was a factor for decreasing mortality in female (HR, 0.81; 95% CL, 0.77-0.84, P < 0.001), with mortality reduction of 10% at the 3- and 5-year survival time-points. In female patients, chest radiography surveillance at intervals of less than 3 years was an independent predictor of improved survival.

CONCLUSIONS

Surveillance chest radiography increased survival in a female screened population in South Korea. Chest radiography intervals of less than 3 years may help to detect lung cancer in female patients.

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.

Evaluation of the 95% limits of agreement of the volumes of 5-year clinically stable solid nodules for the development of a follow-up system for indeterminate solid nodules in CT lung cancer screening

Background

This study sought to evaluate the 95% limits of agreement of the volumes of 5-year clinically stable solid nodules for the development of a follow-up system for indeterminate solid nodules.

Methods

The volumes of 226 solid nodules that had been clinically stable for 5 years were measured in 186 patients (53 female never-smokers, 36 male never-smokers, 51 males with <30 pack-years, and 46 males with ≥30 pack-years) using a three-dimensional semiautomated method. Volume changes were evaluated using three methods: percent change, proportional change and growth rate. The 95% limits of agreement were evaluated using the Bland-Altman method.

Results

The 95% limits of agreement were as follows: range of percent change, from ±34.5% to ±37.8%; range of proportional change, from ±34.1% to ±36.8%; and range of growth rate, from ±39.2% to ±47.4%. Percent change-based, proportional change-based, and growth rate-based diagnoses of an increase or decrease in ten solid nodules were made at a mean of 302±402, 367±455, and 329±496 days, respectively, compared with a clinical diagnosis made at 809±616 days (P<0.05).

Conclusions

The 95% limits of agreement for volume change in 5-year stable solid nodules may enable the detection of an increase or decrease in the solid nodule at an earlier stage than that enabled by a clinical diagnosis, possibly contributing to the development of a follow-up system for reducing the number of additional Computed tomography (CT) scans performed during the follow-up period.

The Effect of False-Positive Results on Subsequent Participation in Chest X-ray Screening for Lung Cancer

BACKGROUND

High attendance rates and regular participation in disease screening programs are important contributors to program effectiveness. The objective of this study was to examine the effects of an initial false-positive result in chest X-ray screening for lung cancer on subsequent screening participation.

METHODS

This historical cohort study analyzed individuals who first participated in a lung cancer screening program conducted by Yokohama City between April 2007 and March 2011, and these participants were retrospectively tracked until March 2013. Subsequent screening participation was compared between participants with false-positive results and those with negative results in evaluation periods between 365 (for the primary outcome) and 730 days. The association of screening results with subsequent participation was evaluated using a generalized linear regression model, with adjustment for characteristics of patients and screening.

RESULTS

The proportions of subsequent screening participation within 365 days were 12.9% in 3132 participants with false-positive results and 6.7% in 15 737 participants with negative results. Although the differences in attendance rates were reduced with longer cutoffs, participants with false-positive results were consistently more likely to attend subsequent screening than patients with negative results (P < 0.01). The predictors of subsequent screening participation were false-positive results (risk ratio [RR] 1.72; 95% confidence interval [CI], 1.54-1.92), older age (RR 1.17; 95% CI, 1.11-1.23), male sex (RR 1.46; 95% CI, 1.29-1.64), being a current smoker (RR 0.80; 95% CI, 0.69-0.93), current employment (RR 0.79; 95% CI, 0.70-0.90), and being screened at a hospital cancer center (vs public health centers; RR 1.36; 95% CI, 1.15-1.60).

CONCLUSIONS

Our findings indicated that subsequent participation in lung cancer screening was more likely among participants with false-positive results in an initial screening than patients with negative results.

Low-dose computed tomography screening in Japan

Lung cancer is a leading cause of cancer death in both male and female individuals in Japan. The effect of screening using chest radiography is assumed to be limited. In Japan, screening using low-dose computed tomography (CT) was initiated in 1993, and its dissemination has progressed with studies evaluating its efficacy, although it is not officially recommended. In addition to the academic activities of the Japanese Society of CT Screening, certification of physicians and radiologic technologists by the Japan Accreditation Council for CT Screening has been progressing. Currently, several hundred thousand low-dose CT screenings are performed annually in Japan. In Hitachi City, Ibaraki Prefecture, low-dose CT screening among employees and in communities started in 2001, and it was estimated that 40% of 50- to 69-year-old citizens had undergone screening at least once by March 2009. The lung cancer mortality rate in citizens in this age group decreased by 24% in 2005 to 2009 compared with the national statistics. Low-dose CT screening targeting the general population may be effective, but it is necessary to consider the target and interval of screening separately from those for the high-risk group. Observational study may play a role in evaluating the efficacy of screening in Japan.

A survey about further work-up for cases with positive sputum cytology during lung cancer mass screening in Ishikawa Prefecture, Japan: a retrospective analysis about quality assurance of lung cancer screening

OBJECTIVE

In cancer screening programs, performing appropriate further work-up is essential. In order to elucidate whether the further work-up for the subjects with positive screening results by sputum cytology was performed appropriately, the present study was conducted as the first large-scale thorough survey in Japan.

METHODS

All of the lung cancer screening records from 2007 to 2012 in Ishikawa Prefecture were reviewed. Additional investigations about the further work-up were performed.

RESULTS

In total, 2 234 984 people were invited to undergo lung cancer screening, and 494 424 people participated in the screening. Of these, 25 264 people underwent sputum cytology, and 68 positive cases were identified. Three of these 68 cases did not undergo further work-up, and another three cases had already been diagnosed to have lung cancer. Forty-five of the remaining 62 cases did not have suspicious chest shadows, and bronchoscopic examinations were performed in 36 cases. Seventeen of these 36 cases were diagnosed as having cancer, whereas none of the nine cases who did not receive the examination was diagnosed (P = 0.038). A bronchoscopic examination was not performed due to other medical conditions in three cases, due to the patient's refusal in another three cases and in the remaining three cases, the reasons were unknown.

CONCLUSION

The participation rate for further work-up was very high. However, there are some issues to be resolved regarding the transmission of information. With our new registered hospital system, the quality assurance of our screening program will be improved.

Lung cancer screening-don’t forget the chest radiograph

Lung cancer is a major health burden and early detection only bears the possibility of curative treatment. Screening with computed tomography (CT) recently demonstrated a mortality reduction in selected patients and has been incorporated in clinical guidelines. Problems of screening with CT are the excessive number of false positive findings, costs, radiation burden and from a global point of view shortage of CT capacity. In contrast, chest radiography could be an ideal screening tool in the early detection of lung cancer. It is widely available, easy to perform, cheap, the radiation burden is negligible and there is only a low rate of false positive findings. Large randomized controlled trials could not show a mortality reduction, but different large population-based cohort studies have shown a lung cancer mortality reduction. It has been argued that community-based cohort studies are more closely reflecting the “real world” of everyday medicine. Radiologists should be aware of the found mortality reduction and realize that early detection of lung cancer is possible when reading their daily chest radiographs. Offering a chest radiograph in selected scenarios for the early detection of lung cancer is therefore still justified.

Assessment of lung cancer mortality reduction after chest X-ray screening in smokers: a population-based cohort study in Varese, Italy

BACKGROUND

The effectiveness of screening for lung cancer (LC) in smokers on a population level, as distinct from the special circumstances that may apply in a randomized trial of selected volunteers, has not been thoroughly investigated. Here we evaluate by the standardized mortality ratio (SMR) indicator the impact of a chest X-ray (CXR) screening programme carried out at community level on LC mortality in smokers.

METHODS

All smokers of >10 pack-years, of both genders, ages 45-75 years, resident in 50 communities of the Province of Varese, Italy, screening-eligible, in 1997 were invited by their National Health Service (NHS) general practitioner physicians to a nonrandomized programme of five annual CXR screenings. The entire invitation-to-screen cohort (n=5815 subjects) received NHS usual care, with the addition of CXR exams in volunteer participants (21% of invitees), and was observed through December 2006. To overcome participants' selection bias of LC mortality assessment, for the entire invitation-to-screen cohort we estimated the LC-specific SMR, based on the local reference population receiving the NHS usual care.

RESULTS

Over the 8-year period 1999-2006, a total of 172 cumulative LC deaths were observed in the invitation-to-screen cohort; 210 were expected based on the reference population. Each year in the invited cohort the observed LC deaths were fewer than expected. The cumulative LC SMR was 0.82 (95% CI, 0.67-0.99; p=0.048), suggesting that LC mortality was reduced by 18% with CXR screening.

CONCLUSION

Implementation of a CXR screening programme at community level was associated with a significant reduction of LC mortality in smokers.

Interventional study for improvement of lung cancer screening rate

The aim of this study is to evaluate whether leaflet distribution affects lung screening rate, and what factor affects the motivation of consultation. Men and women aged 40 to 59 were targeted to improve screening rate of ages for cancer screening, especially in their prime. Each 1,000 subject, a total of 2,000 were selected and divided into 8 groups in consideration of age group by random sampling method. This group was further divided into two groups, an intervention group including subjects distributed a leaflet and a non-intervention (control) group. A survey was conducted by postal self-administered survey forms. Collection rate was 21.6% for the intervention and 17.6% for the control group. The numbers of respondents who answered that this leaflet was effective for motivation of consulting lung cancer screening and the leaflet was ineffective, were 120 (60.0%) and 80 (40.0%), respectively. This indicated that the leaflet was clearly effective (p<0.01). Actual cancer screening rate was 38.8% for the intervention group and 37.7% for the control group. It was shown that distribution by mail of even a single leaflet made by National Cancer Center was effective for motivation of consultation of lung cancer screening.

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.

Different efficacy of CT screening for lung cancer according to histological type: analysis of Japanese-smoker cases detected using a low-dose CT screen

The efficacy of CT screening for lung cancers is still a controversial issue, although one of the recently publicized large randomized controlled trials of this methodology, the National Lung Screening Trial (NLST), reported a decrease in the lung cancer-specific mortality for heavy smokers. We here performed case-matched comparative analyses, as a retrospective study, of three lung cancer arms detected by CT screen, X-ray screen, and by individual analysis of the clinicopathological features and outcomes in smokers from a symptomatic-prompted group of patients. We also considered the impacts of various potential biases in this cohort. The total study cohort comprised 136 patients in the CT screen group, 263 in the X-ray screen group and 254 in the symptomatic-prompted group. The ratio of stage IA cancers in the CT screen group was 67.7% and the ratio of advanced cases (i.e. stages IIIB+IV) was 12.5%. The percentage of bronchioloalveolar carcinoma (BAC) was 28.7% in the CT screen group. The 5-year survival rates were 82.4% in the CT screen group, 38.0% in the X-ray screen group and 17.8% in the symptomatic-prompted group. CT screening was found to be an independent prognostic factor for lung cancer even when BAC cases were eliminated (HR 0.35, P<0.01). Based on our sub-analysis by individual histological sub-type, CT screen lung cancer cases had a better survival rate than non-screened patients, which included adenocarcinoma, squamous cell carcinoma and large/small cell carcinoma. However, by multi-variant analysis a CT scan would not be expected to reduce the risk of lung cancer mortality in patients with large/small cell carcinoma, although would be expected to reduce the risk of lung cancer death by 80% in cases of both adenocarcinoma and squamous cell carcinoma. In conclusion, our current findings indicate that CT screening for lung cancer is an effective strategy for smokers and that patients with adenocarcinoma and squamous cell carcinoma of all variant histological types may benefit from this test. In this regard, early stage large/small cell carcinomas are insufficiently detected by the existing annual screening system.

Evaluation of cancer service screening: case referent studies recommended

Various cancer screening trials, randomised or otherwise controlled, have demonstrated reductions in cancer mortality. As a consequence, population screening programmes have been implemented. In the mean time, major advances are being made in early detection and treatment modalities of specific cancers and pre-cancers. The impact of these improvements should have bearing on the beneficial effect of periodical screening in preventing cancer death. To monitor these dynamics in the effectiveness of screening, case-referent studies are designed. The effectiveness is estimated by calculating an odds ratio indicating the cancer death rate in screened versus not screened invitees. The major criticisms of case referent studies are potential selection bias and confounding bias of the odds ratio. By properly designing and applying sensitivity analyses these biases can be minimised.

Lung cancer screening and its efficacy

The efficacy of lung cancer screening should not be evaluated by the survival rate of lung cancer patients but by lung cancer mortality in a certain population because the survival rate can be greatly affected by several types of bias. Randomized controlled trials that were conducted during the 1970s and 1980s in Europe and the United States failed to prove the efficacy of lung cancer screening in decreasing the mortality rate; but recently the results of case-control studies in Japan have revealed that undergoing currently available screening decreases the risk of lung cancer deaths by 30%-60%. A system is now being created in Japan whereby the guidelines regarding cancer screening will continue to be updated. The preliminary reports concerning lung cancer screening using thoracic computed tomography revealed that not only the detection rate of lung cancer but also the survival rate of detected lung cancer patients were surprisingly high. However, the presence of some potential bias in these studies cannot be ignored; therefore, it is still unknown whether there is actual efficacy. Several randomized controlled trials are presently in progress overseas, but the interim results were not favorable. A randomized controlled trial should therefore immediately be started in Japan as well.

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.

Screening for lung cancer: a review

PURPOSE OF REVIEW

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

RECENT FINDINGS

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

SUMMARY

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

The Natural History of Radiographically Occult Bronchogenic Squamous Cell Carcinoma

OBJECTIVE

An overdiagnosis bias occurs with the diagnosis of a disease that does not produce signs or symptoms before the patient dies from other causes. We sought to determine whether overdiagnosis bias is a factor when screening for squamous cell carcinoma of the lung.

DESIGN

Retrospective study of the Miyagi Population-Based Lung Cancer Screening Registry for high-risk patients who were seen between January 1, 1982 (when sputum cytology tests were added for men with long smoking histories), and December 31, 1996.

SETTING

Miyagi Prefecture, Japan.

PATIENTS

A total of 251 patients (all men) who had sputum cytology test results that were positive for squamous cell carcinoma but had normal radiograph findings, 44 of whom declined cancer treatment (mean age, 70 years) and 207 of whom were treated with resection within 12 weeks of diagnosis (mean age, 65.5 year).

END POINTS

Five-year and 10-year survival rates from primary lung cancer in both groups as of August 15, 2001.

RESULTS

Among the 44 untreated patients, 15 (34%) remained asymptomatic. The survival rate due to primary lung cancer death in the untreated group was 53.2% at 5 years and 33.5% at 10 years. The survival rate among treated patients was 96.7% at 5 years and 94.9% at 10 years. Of the 125 treated patients who died, 14 (11.2%) died from primary lung cancer.

CONCLUSION

Given that the two thirds of the untreated patients with squamous cell carcinoma of the bronchus died from lung cancer within 10 years, overdiagnosis bias does not appear to be a factor in screening for this disease. Thus, we recommend that patients with radiographically occult squamous cell carcinoma of the bronchus undergo tumor treatment after localization.

Screening for lung cancer

PURPOSE OF REVIEW

With the development of newer forms of technology such as low-dose spiral computed tomography, there has been a resurgent interest in screening for lung cancer. The purpose of this review is to highlight recent advances in screening for lung cancer. Articles published since September 2002 are reviewed here.

RECENT FINDINGS

More frequent screenings (every 4 or 6 months) showed increased mortality from lung cancer, compared with annual screening. A mass screening conducted in 1990 was effective in a case-control study. The results of lung cancer screening by low-dose spiral computed tomography were reported from the Milan group and the Mayo Clinic. Computed tomography depicted peripheral early lung cancer, especially adenocarcinoma. These results are consistent with previous reports from other groups. Screening with imaging becomes more sensitive with automated computerized methods.

SUMMARY

A high percentage of stage IA lung cancers were detected by screening with low-dose helical computed tomography. The characteristics of the nodules detected by low-dose spiral computed tomography have been clarified. There have been many controversial discussions about cost effectiveness and overdiagnosis. There is still no evidence that screening tests reduce the rate of cancer-specific mortality. Several studies of screening for lung cancer are under way.