Screening for early lung cancer with low-dose spiral computed tomography

Clinical significance of perifissural nodules in the oncologic population

PURPOSE

To evaluate for stability of perifissural nodules (PFNs) in a dedicated oncologic population.

METHODS

A retrospective review of 500 computed tomography (CT) chests from oncologic patients at our tertiary care cancer center with at least a three year follow up yielded 76 patients with PFNs. Patients with metastases on baseline CT chest were excluded (n = 14) as the presence of a PFN would not be clinically relevant, thus our final patient cohort was 62 patients with a total of 112 PFNs. PFN features, clinical features, and ancillary information was recorded from the CT and the electronic medical record for all patients. The two patient cohorts-stable or decreased PFN vs. increased PFN-were then compared.

RESULTS

112 PFNs were examined in 62 patients with a median follow up interval of 5.7 years. Of 62 patients, 59 (95.2%, 95% CI: 86.5, 99.0) had decreased/stable PFNs on follow up scan (median follow up 5.6 years) and 3 (4.8%, 95% CI: 1.0, 13.5%) had enlarged PFNs (median follow up 6.3 years). None of the PFN features, clinical features, nor ancillary information from the CT proved to be statistically significant.

CONCLUSIONS

Despite the lack of statistically significant distinguishing features to predict growth, our results are reassuring, since the majority of PFNs in our oncology patients were decreased or unchanged in size which is comparable to previously published data on PFNs in non-oncologic patients. Thus, we can similarly presume these nodules are most likely benign and can provide reassurance to our oncologic colleagues and our patients. Larger studies are warranted to further evaluate PFNs in the oncologic population which also examines the nodules by cancer type.

Lung cancer screening: rationale and background

The poor outcome in symptomatic lung cancer patients and the much better prognosis when lung cancer is diagnosed and treated at early asymptomatic stages call for screening. As lung cancer predominantly affects smokers and individuals exposed to other carcinogens, screening programs need not include the whole population but only these risk groups. Every screening program will tend to better identify the more indolent tumours that grow slowly enough to be detected by screening before symptoms develop, whereas aggressive fast-growing tumours may present as interval cancers despite screening (length-time bias). Some malignant tumours detected with screening may never cause the person’s death due to competing causes for death, particularly in heavy smokers, such as cardiovascular disease or other cancers (overdiagnosis bias). If a cancer is still lethal despite detection through screening, the affected individual may live longer with the diagnosis of cancer but not longer altogether (lead-time bias). It is likely that this will have a negative effect on that individual’s quality of life. Participation in screening programs may have beneficial as well as adverse effects on smoking habits; in the worst case it may encourage people to continue smoking. Trials assessing chest radiography or sputum microscopy have not demonstrated a reduction in lung cancer mortality through screening, probably because the tests were not sensitive enough. computed tomography promises better sensitivity. Other modern tests such as fibre optic bronchoscopy, analysis of molecular markers or genetic testing in serum, sputum or exhaled air are not yet ready for clinical practice.

Computer-aided detection of lung nodules: influence of the image reconstruction kernel for computer-aided detection performance

OBJECTIVE

To evaluate the relationship between a computed tomographic reconstruction kernel and the sensitivity of a computer-aided detection (CAD) system for lung nodule detection.

METHODS

We retrospectively studied 36 consecutive patients with no known pulmonary nodules who underwent low-dose computed tomography for lung cancer screening with 3 different reconstruction kernels (B, C, and L). All series were reviewed with a commercial CAD system for lung nodule detection.

RESULTS

The 36 scans showed 231 uncalcified nodules (170 micronodules and 61 nodules). There was little variation of sensitivities for each series (82%, 88%, and 82% for the nodules of B, C, and L, respectively). When the results of 2 series were combined, sensitivities were boosted (B + C, 89%; B + L, 95%; and C + L, 96% for the nodules).

CONCLUSIONS

Sensitivity of the CAD system was influenced by the selection of the reconstruction kernel. By combining data from 2 different kernels, CAD sensitivity can be elevated without further patient radiation exposure.

Solitary pulmonary nodule: detection and management

Pulmonary nodules are commonly detected at computed tomography (CT) of the chest. More than 95% are \documentclass[12pt]{minimal} \usepackage{wasysym} \usepackage[substack]{amsmath} \usepackage{amsfonts,amssymb,amsbsy} \usepackage[mathscr]{eucal} \usepackage{mathrsfs} \DeclareFontFamily{T1}{linotext}{} \DeclareFontShape{T1}{linotext}{m}{n}{<-> linotext}{} \DeclareSymbolFont{linotext}{T1}{linotext}{m}{n} \DeclareSymbolFontAlphabet{\mathLINOTEXT}{linotext} \begin{document} $\le $ \end{document} 10 mm; of these more than 95% are benign. Visual detection of pulmonary nodules by human readers is suboptimal, particularly with small nodules \documentclass[12pt]{minimal} \usepackage{wasysym} \usepackage[substack]{amsmath} \usepackage{amsfonts,amssymb,amsbsy} \usepackage[mathscr]{eucal} \usepackage{mathrsfs} \DeclareFontFamily{T1}{linotext}{} \DeclareFontShape{T1}{linotext}{m}{n}{<-> linotext}{} \DeclareSymbolFont{linotext}{T1}{linotext}{m}{n} \DeclareSymbolFontAlphabet{\mathLINOTEXT}{linotext} \begin{document} $\le $ \end{document} 10 mm. Computer-assisted detection can improve sensitivity and diagnostic confidence. Due to the high proportion of malignant lesions in nodules >10 mm immediate, often invasive work-up is required including contrast-enhanced dynamic CT, positron emission tomography (PET) or biopsy. However, in nodules \documentclass[12pt]{minimal} \usepackage{wasysym} \usepackage[substack]{amsmath} \usepackage{amsfonts,amssymb,amsbsy} \usepackage[mathscr]{eucal} \usepackage{mathrsfs} \DeclareFontFamily{T1}{linotext}{} \DeclareFontShape{T1}{linotext}{m}{n}{<-> linotext}{} \DeclareSymbolFont{linotext}{T1}{linotext}{m}{n} \DeclareSymbolFontAlphabet{\mathLINOTEXT}{linotext} \begin{document} $\le $ \end{document} 10 mm the high proportion of benign lesions requires a non-invasive work-up usually based on follow-up with unenhanced CT. Invasive procedures are only required for growing nodules. Stable nodules require further follow-up and decreasing nodules are considered benign.

CT and MRI of Lung Cancer

Computed tomography (CT) is still the cornerstone of imaging studies in the preoperative staging and post- therapeutic evaluation of lung cancer. The most recent developments in multidetector technology have dramatically improved the temporal and spatial resolution of CT. In the mean time, magnetic resonance imaging (MRI) has not become a routine examination in lung imaging and is today only used as a problem-solving tool in patients in whom CT remains equivocal. This article will describe the current tools developed in the multidetector CT era for evaluating the lung, and state-of-the-art MR examination of the chest. Then, the role of CT and MRI in nodule detection, the distinction between benign and malignant nodules, and the benefit of CT and MRI in the staging and post-therapeutic evaluation of lung cancer will be covered.

[Pulmonary tumors]

Pulmonary nodules may be caused by true neoplasms of the airways, respiratory epithelium, vessels and connective tissue which are mainly malignant or metastatic. They may, however, also represent mainly inflammatory benign pseudotumours. Non-small cell lung cancer (NSCLC) usually presents as an ill-defined soft-tissue pulmonary nodule or mass, often without lymphadenopathy; endobronchial lesions are less common. Small cell lung cancer (SCLC) commonly presents with extensive lymph node and hematogenous metastases. Carcinoid tumors typically manifest as endobronchial lesions with secondary obstruction. Sarcomas are rare and show variable morphology. Metastases most commonly present as basal, peripheral, well-defined nodules. Granulomas often exhibit typical calcifications; hamartoma may also contain popcorn-type calcifications as well as fat. Pulmonary arteriovenous malformation is characterised by feeding artery and draining vein. Inflammatory nodules are well vascularized and may regress spontaneously; their differentiation from malignant lesions, however, is usually difficult.

Lung cancer after treatment for Hodgkin's lymphoma: a systematic review

Developments in modern chemotherapy and radiotherapy mean that most patients with Hodgkin's lymphoma can now be cured. However, the long-term effects of anticancer treatment include an increased risk of a second malignant disease. We have done a systematic review of studies reporting long-term complications of the treatment of Hodgkin's lymphoma published in English since 1985. These studies show that risk of lung cancer is significantly increased in patients treated for Hodgkin's lymphoma, with a reported mean relative risk of 2.6-7.0 and a significantly increased absolute excess risk. The absolute excess risk increases with time from treatment, for as long as 20-25 years, and is highest in patients treated at age 45 years or older. Both chemotherapy and radiotherapy contribute to the risk, and evidence suggests that the effects are additive. Cigarette smoking seems to multiply the risk associated with both chemotherapy and radiotherapy. In the high-risk group of patients, 50-150 patients per 1000 are expected to develop lung cancer by 10-20 years after treatment. The role of screening in this group of patients has not yet been assessed, but an international study combining CT with genomic and proteomic assessment is planned.

Resolving small pulmonary nodules: CT features

Our aim was to analyse the CT morphology of resolving nodules over time in order seek morphologic features helpful in initial nodule classification. The imaging characteristics of 133 consecutive resolving pulmonary nodules detected in 56 subjects in a screening trial for early lung cancer with low-dose CT were retrospectively reviewed by two readers in consensus. Nodule size ranged from 2 to 28 mm, with a mean diameter of 5.9 mm. The maximum diameter of resolving nodules was < or =5 mm in 71/133 (53%), 6-10 mm in 52/133 (39%), and >10 mm in 10/133 (8%). Their location was mainly peripheral, with a mean distance to the costal pleura of 10 mm. There was no lobe predominance of nodules. In 85% (113/133) of cases the nodules were solid, 77% (103/133) were well-defined, and 73% (97/133) were non-lobulated. Eighty percent (107/133) resolved completely within 14-1,671 (mean 492) days, 20% (26/133) resolved incompletely with residual abnormalities within 51-1,777 (mean 613) days. Resolving pulmonary nodules were mostly < or =10 mm, peripherally located, solid, well-defined, and non-lobulated. Most resolve completely within a variable interval ranging from several days to years.

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.

Early lung cancer detection using spiral computed tomography and positron emission tomography

RATIONALE

Lung cancer screening using computed tomography (CT) is effective in detecting lung cancer in early stages. Concerns regarding false-positive rates and unnecessary invasive procedures have been raised.

OBJECTIVE

To study the efficiency of a lung cancer protocol using spiral CT and F-18-fluorodeoxyglucose positron emission tomography (FDG-PET).

METHODS

High-risk individuals underwent screening with annual spiral CTs. Follow-up CTs were done for noncalcified nodules of 5 mm or greater, and FDG-PET was done for nodules 10 mm or larger or smaller (> 7 mm), growing nodules.

RESULTS

A total of 911 individuals completed a baseline CT study and 424 had at least one annual follow-up study. Of the former, 14% had noncalcified nodules of 5 mm or larger, and 3.6% had nodules of 10 mm or larger. Eleven non-small cell lung cancers (NSCLC) and one small cell lung cancer (SCLC) were diagnosed in the baseline study (prevalence rate, 1.32%), and two NSCLCs in the annual study (incidence rate, 0.47%). All NSCLCs (92% of prevalence cancers) were diagnosed in stage I (12 stage IA, 1 stage IB). FDG-PET was helpful for the correct diagnosis in 19 of 25 indeterminate nodules. The sensitivity, specificity, positive predictive value, and negative predictive value of FDG-PET for the diagnosis of malignancy were 69, 91, 90, and 71%, respectively. However, the sensitivity and negative predictive value of the screening algorithm, which included a 3-month follow-up CT for nodules with a negative FDG-PET, was 100%.

CONCLUSION

A protocol for early lung cancer detection using spiral CT and FDG-PET is useful and may minimize unnecessary invasive procedures for benign lesions.

Frozen section diagnoses of small pulmonary nodules: accuracy and clinical implications

BACKGROUND

Pulmonary nodules are frequently first diagnosed by frozen section, immediately followed by lobectomy or other procedures. The frozen section diagnosis of pulmonary nodules can be difficult, as inflammatory and fibrotic lesions can be confused for malignancy, creating intraoperative dilemmas for pathologists and thoracic surgeons.

METHODS

We reviewed our experience at Cedars-Sinai Medical Center with the frozen section diagnoses of 183 consecutive pulmonary nodules smaller than 1.5 cm in diameter and calculated the sensitivity, specificity, and predictive values of this diagnostic procedure.

RESULTS

One hundred and seventy four nodules were correctly classified by frozen section as neoplastic or nonneoplastic, six lesions were diagnosed equivocally, and two neoplasms were missed owing to sampling errors. The equivocal frozen section diagnoses included two bronchioloalveolar carcinomas (BAC) interpreted as "atypical hyperplasia, favor BAC," two BAC diagnosed as "alveolar hyperplasia," and two carcinoid tumors labeled as "atypical carcinoma" and "spindle cell lesion, carcinoid versus sclerosing hemangioma," respectively. The sensitivities for a diagnosis of neoplasia were 86.9% and 94.1% for nodules smaller than 1.1 cm in diameter and measuring 1.1 to 1.5 cm, respectively. The diagnostic accuracy of frozen sections was significantly better in nodules larger than 1.0 cm in diameter (p = 0.05). There were no false-positive diagnoses of malignancy, resulting in 100% specificity.

CONCLUSIONS

Intraoperative consultation with frozen section is a sensitive and specific procedure for the diagnosis of malignancy from small pulmonary nodules. The distinction between BAC and atypical adenomatous hyperplasia, and of small peripheral carcinoid tumors from other lesions, can be difficult by frozen section. Thoracic surgeons need to become aware of these problems and develop appropriate therapeutic strategies.

Impact of low-dose CT on lung cancer screening

Despite advances in therapy, the prognosis of lung cancer remains dismal due to the fact that most cases of lung cancer are diagnosed at advanced stages, when the chance of cure is poor. In cases detected at early stages prognosis is better. Unfortunately, early lung cancer usually causes no symptoms and is, consequently, rarely diagnosed. Therefore, screening for early asymptomatic lung cancer with diagnostic procedures appears promising particularly as risk factors for lung cancer are well known (cigarette smoking, occupational asbestos exposure and others) and screening could, therefore, focus on these risk groups. In the past, screening trials using analysis of sputum cytology and to some extent chest radiography have failed to demonstrate a reduction in lung-cancer mortality with screening, probably due to insufficient sensitivity of these tests for early lung cancer. During the last decade the introduction of spiral computed tomography (CT) has provided a technique with a much higher sensitivity for small lung cancers. Feasibility studies using low-radiation-dose CT demonstrated a high proportion of non-small-cell lung cancer at the initial examination (prevalence) with decreasing numbers of detected cancers at follow-up (incidence). The proportion of early-stage tumors was high both at prevalence and incidence examinations. The rate of invasive procedures for benign lesions was low; most indeterminate lesions could be classified with non-invasive diagnostic approaches. The proportion of interval cancers (cancers diagnosed by symptoms between two screening CT scans) was low. As, however, these one-arm feasibility trials are not appropriate to assess a potential mortality reduction through CT screening, prospective randomised multicenter trials were recently initiated in several countries to analyse the effect of CT screening on lung-cancer mortality.