What is early lung cancer? A review of the literature

Advancements in the diagnosis and treatment of sub‑centimeter lung cancer in the era of precision medicine (Review)

Lung cancer is the malignancy with the highest global mortality rate and imposes a substantial burden on society. The increasing popularity of lung cancer screening has led to increasing number of patients being diagnosed with pulmonary nodules due to their potential for malignancy, causing considerable distress in the affected population. However, the diagnosis and treatment of sub-centimeter grade pulmonary nodules remain controversial. The evolution of genetic detection technology and the development of targeted drugs have positioned the diagnosis and treatment of lung cancer in the precision medicine era, leading to a marked improvement in the survival rate of patients with lung cancer. It has been established that lung cancer driver genes serve a key role in the development and progression of sub-centimeter lung cancer. The present review aimed to consolidate the findings on genes associated with sub-centimeter lung cancer, with the intent of serving as a reference for future studies and the personalized management of sub-centimeter lung cancer through genetic testing.

Quantitative PET/MR imaging of lung cancer in the presence of artifacts in the MR-based attenuation correction maps

Background

Positron emission tomography (PET)/magnetic resonance (MR) imaging may become increasingly important for assessing tumor therapy response. A prerequisite for quantitative PET/MR imaging is reliable and repeatable MR-based attenuation correction (AC).

Purpose

To investigate the frequency and test–retest reproducibility of artifacts in MR-AC maps in a lung cancer patient cohort and to study the impact of artifact corrections on PET-based tumor quantification.

Material and Methods

Twenty-five lung cancer patients underwent single-day, test–retest, 18F-fluorodeoxyglucose (FDG) PET/MR imaging. The acquired MR-AC maps were inspected for truncation, susceptibility, and tissue inversion artifacts. An anatomy-based bone template and a PET-based estimation of truncated arms were employed, while susceptibility artifacts were corrected manually. We report the frequencies of artifacts and the relative difference (RD) on standardized uptake value (SUV) based quantification in PET images reconstructed with the corrected AC maps.

Results

Truncation artifacts were found in all 50 acquisitions (100%), while susceptibility and tissue inversion artifacts were observed in six (12%) and 26 (52%) of the scans, respectively. The RD in lung tumor SUV was < 5% from bone and truncation corrections, while up to 20% RD was introduced after susceptibility artifact correction, with large inconsistencies between test–retest scans.

Conclusion

The absence of bone and truncation artifacts have limited effect on the PET quantification of lung lesions. In contrast, susceptibility artifacts caused significant and inconsistent underestimations of the lung tumor SUVs, between test–retest scans. This may have clinical implications for patients undergoing serial imaging for tumor therapy response assessment.

Real-time in vivo cancer diagnosis using Raman spectroscopy

Raman spectroscopy has becoming a practical tool for rapid in vivo tissue diagnosis. This paper provides an overview on the latest development of real-time in vivo Raman systems for cancer detection. Instrumentation, data handling, as well as oncology applications of Raman techniques were covered. Optic fiber probes designs for Raman spectroscopy were discussed. Spectral data pre-processing, feature extraction, and classification between normal/benign and malignant tissues were surveyed. Applications of Raman techniques for clinical diagnosis for different types of cancers, including skin cancer, lung cancer, stomach cancer, oesophageal cancer, colorectal cancer, cervical cancer, and breast cancer, were summarized. Schematic of a real-time Raman spectrometer for skin cancer detection. Without correction, the image captured on CCD camera for a straight entrance slit has a curvature. By arranging the optic fiber array in reverse orientation, the curvature could be effectively corrected.

Pulmonary malignant focal ground-glass opacity nodules and solid nodules of 3cm or less: comparison of multi-detector CT features

INTRODUCTION

To evaluate the different multi-detector computed tomography (MDCT) features between pulmonary malignant focal ground-glass opacity (fGGO) nodules and solid nodules of 3cm or less in diameter.

METHODS

One hundred and five malignant solid nodules and 48 malignant fGGOs confirmed by pathology were retrospectively analysed with regard to the patient's demographic data, nodule size and MDCT features (shape, margin, interface, internal characteristics and adjacent structure). Differences were analysed using the Fisher exact test or Mann-Whitney U-test.

RESULTS

The male to female ratio of patients with malignant solid nodules (60:45) was higher than that with malignant fGGOs (18:30) (P<0.05). There was no significant difference in either patient's age (P>0.05) or nodule size (P>0.05). The frequency of irregular shape (4% vs. 21%), spiculation (57% vs. 40%), vacuole sign (11% vs. 52%) and natural air bronchograms (0% vs. 24%) was significantly different between malignant solid nodules and fGGOs. No differences were found in the frequency of lobulation, cusp angle, spine-like process, interface and adjacent structure between the two groups (P>0.05).

CONCLUSION

Malignant fGGOs and solid nodules showed mostly similar MDCT features. For malignant fGGOs, the frequency of irregular shape, vacuole sign and natural air bronchograms was higher than that in solid nodules, but the frequency of spiculation was lower than that in solid nodules.

A clinicopathological study of resected non-small cell lung cancers 2 cm or less in diameter: a prognostic assessment

The detection and diagnosis of small-sized (2 cm or less) non-small cell lung cancer (NSCLC) has increased with the development of computed tomography (CT). Over 80% of 5-year survival rate has been reported in surgically treated peripheral lung cancer. There are systematic mediastinal and hilar lymph node involvement pleural invasion and intrapulmonary metastasis even with tumor diameter less than 2 cm. The appropriate surgical procedure for such kinds of lung cancer is lobectomy with mediastinal lymph node dissection. To evaluate the prognostic factors and establish the optimal surgical strategy, we analyzed the clinicopathologic features and survival benefit in different tumor size of peripheral small-sized NSCLC. Among the resected lung cancer cases between January 1999 and July 2001, 185 patients were retrospectively analyzed in surgical methods, lymph node involvement, CT scan findings and survival rates. Survival was analyzed by Kaplan-Meier method and log-rank test. Lymph node involvement was recognized in 26(14.05%) patients. There was no statistically significant difference in the incidence of lymph node involvement between tumors 1.6-2.0 cm (17.82%) in diameter than in those 1.0-1.5 cm (11.94%). There was no lymph node metastasis in tumors less than 1.0 cm in diameter. The 5-year survival rates with or without lymph node involvement were 89.98 and 46.15%, respectively, showing significant difference (P=0.000). The overall 5-year survival rate was 83.78%. The 5-year survival rate in tumors 1.6-2.0 cm, 1.0-1.5 cm and less than 1.0 cm in diameter was 80.20, 85.07 and 100%, respectively, and showing significant difference (P=0.035). The 5-year survival rate of 19 patients showing ground-glass opacity (GGO) on CT scan was 94.74% without any metastasis and recurrence after operation. There are systematic mediastinal and hilar lymph node involvement even with tumor diameter less than 2 cm. The results of the present study suggested that systematic lymph node dissection is necessary even for cases with tumor diameter less than 2 cm. However, if the tumor is within 1.0 cm in diameter with obvious GGO showing on chest CT scan, these are good candidates for partial resection without mediastinal lymph node dissection.

Results of combined photodynamic therapy (PDT) and high dose rate brachytherapy (HDR) in treatment of obstructive endobronchial non-small cell lung cancer (NSCLC)

INTRODUCTION

We reviewed the outcome of combined photodynamic therapy (PDT) and high dose rate brachytherapy (HDR) for patients with symptomatic obstruction from endobronchial non-small cell lung cancer.

METHODS

Nine patients who received combined PDT and HDR for endobronchial cancers were identified and their charts reviewed. The patients were eight males and one female aged 52-73 at diagnosis, initially presenting with various stages of disease: stage IA (N=1), stage IIA (N=1), stage III (N=6), and stage IV (N=1). Intervention was with HDR (500 cGy to 5 mm once weekly for 3 weeks) and PDT (2 mg/kg Photofrin, followed by 200 J/cm(2) illumination 48 h post-infusion). Treatment group 1 (TG-1, N=7) received HDR first; Treatment group 2 (TG-2, N=2) received PDT first. Patients were followed by regular bronchoscopies.

RESULTS

Treatments were well tolerated, all patients completed therapy, and none were lost to follow-up. In TG-1, local tumor control was achieved in six of seven patients for: 3 months (until death), 15 months, 2+ years (until death), 2+ years (ongoing), and 5+ years (ongoing, N=2). In TG-2, local control was achieved in only one patient, for 84 days. Morbidities included: soft-tissue contraction and/or other reversible benign local tissue reactions (N=8) and photosensitivity reactions (N=2).

CONCLUSIONS

Combined HDR/PDT treatment for endobronchial tumors is well tolerated and can achieve prolonged local control with acceptable morbidity when PDT follows HDR and when the spacing between treatments is 1 month or less. This treatment regimen should be studied in a larger patient population.

Computer-aided diagnosis of lung cancer: definition and detection of ground-glass opacity type of nodules by high-resolution computed tomography

PURPOSE

The ground-glass opacity (GGO) of lung cancer is identified only subjectively on computed tomography (CT) images as no quantitative characteristic has been defined for GGOs. We sought to define GGOs quantitatively and to differentiate between GGOs and solid-type lung cancers semiautomatically with a computer-aided diagnosis (CAD).

METHODS AND MATERIALS

High-resolution CT images of 100 pulmonary nodules (all peripheral lung cancers) were collected from our clinical records. Two radiologists traced the contours of nodules and distinguished GGOs from solid areas. The CT attenuation value of each area was measured. Differentiation between cancer types was assessed by a receiver-operating characteristic (ROC) analysis.

RESULTS

The mean CT attenuation of the GGO areas was -618.4 +/- 212.2 HU, whereas that of solid areas was -68.1 +/- 230.3 HU. CAD differentiated between solidand GGO-type lung cancers with a sensitivity of 86.0% and specificity of 96.5% when the threshold value was -370 HU. Four nodules of mixed GGOs were incorrectly classified as the solid type. CAD detected 96.3% of GGO areas when the threshold between GGO and solid areas was 194 HU.

CONCLUSION

Objective definition of GGO area by CT attenuation is feasible. This method is useful for semiautomatic differentiation between GGOs and solid types of lung cancer.

Role of baseline nodule density and changes in density and nodule features in the discrimination between benign and malignant solid indeterminate pulmonary nodules

PURPOSE

To retrospectively evaluate whether baseline nodule density or changes in density or nodule features could be used to discriminate between benign and malignant solid indeterminate nodules.

MATERIALS AND METHODS

Solid indeterminate nodules between 50 and 500 mm(3) (4.6-9.8mm) were assessed at 3 and 12 months after baseline lung cancer screening (NELSON study). Nodules were classified based on morphology (spherical or non-spherical), shape (round, polygonal or irregular) and margin (smooth, lobulated, spiculated or irregular). The mean CT density of the nodule was automatically generated in Hounsfield units (HU) by the Lungcare software.

RESULTS

From April 2004 to July 2006, 7310 participants underwent baseline screening. In 312 participants 372 solid purely intra-parenchymal nodules were found. Of them, 16 (4%) were malignant. Benign nodules were 82.8mm(3) (5.4mm) and malignant nodules 274.5mm(3) (8.1mm) (p=0.000). Baseline CT density for benign nodules was 42.7 HU and for malignant nodules -2.2 HU (p=ns). The median change in density for benign nodules was -0.1 HU and for malignant nodules 12.8 HU (p<0.05). Compared to benign nodules, malignant nodules were more often non-spherical, irregular, lobulated or spiculated at baseline, 3-month and 1-year follow-up (p<0.0001). In the majority of the benign and malignant nodules there was no change in morphology, shape and margin during 1 year of follow-up (p=ns).

CONCLUSION

Baseline nodule density and changes in nodule features cannot be used to discriminate between benign and malignant solid indeterminate pulmonary nodules, but an increase in density is suggestive for malignancy and requires a shorter follow-up or a biopsy.

Limited value of shape, margin and CT density in the discrimination between benign and malignant screen detected solid pulmonary nodules of the NELSON trial

PURPOSE

To evaluate prospectively the value of size, shape, margin and density in discriminating between benign and malignant CT screen detected solid non-calcified pulmonary nodules.

MATERIAL AND METHODS

This study was institutional review board approved. For this study 405 participants of the NELSON lung cancer screening trial with 469 indeterminate or potentially malignant solid pulmonary nodules (>50mm3) were selected. The nodules were classified based on size, shape (round, polygonal, irregular) and margin (smooth, lobulated, spiculated). Mean nodule density and nodule volume were automatically generated by software. Analyses were performed by univariate and multivariate logistic regression. Results were presented as likelihood ratios (LR) with 95% confidence intervals (CI). Receiver operating characteristic analysis was performed for mean density as predictor for lung cancer.

RESULTS

Of the 469 nodules, 387 (83%) were between 50 and 500mm3, 82 (17%) >500mm3, 59 (13%) malignant, 410 (87%) benign. The median size of the nodules was 103mm3 (range 50-5486mm3). In multivariate analysis lobulated nodules had LR of 11 compared to smooth; spiculated nodules a LR of 7 compared to smooth; irregular nodules a LR of 6 compared to round and polygonal; volume a LR of 3. The mean nodule CT density did not predict the presence of lung cancer (AUC 0.37, 95% CI 0.32-0.43).

CONCLUSION

In solid non-calcified nodules larger than 50mm3, size and to a lesser extent a lobulated or spiculated margin and irregular shape increased the likelihood that a nodule was malignant. Nodule density had no discriminative power.

Lung cancer screening: has there been any progress? Computed tomography and autofluorescence bronchoscopy

PURPOSE OF REVIEW

Advances in imaging technologies are currently being explored in the attempt to reduce lung cancer morbidity and mortality by achieving stage shift. We reviewed recent important publications on lung cancer screening.

RECENT FINDINGS

Autofluorescence bronchoscopy has established its important role in the intervention of early central airway lesions. Multidetector computed tomography (CT) and CT-positron emission tomography may facilitate diagnosis of early parenchymal lung lesions. Practical implications of screening are reaching far beyond early diagnostic efforts per se as lead-time, length-time, overdiagnosis biases combined with low specificity of screening tests undermine its cost-effectiveness in the era of healthcare budget constraints.

SUMMARY

Advanced imaging technologies may allow early detection and prudent intervention in some individuals that harbour asymptomatic early lung cancer, but disproportional expenses may be required to sieve out many more individuals at risk to attain stage shift. Confounding co-morbidities and practical hurdles may reduce screening's efficacy as it is plausible that for the majority of smokers, lung cancer may not be the ultimate cause of suffering since 90% of them will not develop lung cancer. This fact remains true despite increased use of noninvasive and minimally invasive technologies for the maximum preservation of quality of life irrespective of whether early intervention is a success or failure.

Detection of lung cancer using MAGE A1-6 and SSX4 RT-PCR expression profiles in the bronchial wash fluid

PURPOSE

Bronchial wash fluid may be a useful for detecting lung cancer. To increase the detection rates, we performed molecular analysis with using MAGE A1-6 and SSX4 RT-PCR on bronchial wash fluid specimens.

MATERIALS AND METHODS

We obtained 57 lung cancer tissue specimens by bronchoscopic biopsy and 131 bronchial washes from 96 patients with lung cancer and 35 patients with benign lung diseases. The MAGE A1-6 and SSX4 gene expressions were investigated in the cancer tissue specimens and bronchial wash fluids. We evaluated the positive detection rates of these methods according to the cytology results and the clinical findings.

RESULTS

For the cancer tissue specimens and the bronchial wash fluid, the positive detection rate of MAGE or SSX4 was 91.2% and 75.0%, respectively. Combined MAGE and SSX4 PCR and cytology tests showed an 83.3% detection rate for the bronchial wash fluid. From bronchial washes of patients with benign lung diseases, the positive rates of using MAGE or SSX4 was 11.4%. In the bronchial wash fluid of lung cancer patients, 66.7% of the peripheral cancers were detected by MAGE or SSX4, while examination with cytology did not detect any peripheral lung cancer.

CONCLUSION

The application of both MAGE and SSX4 showed high sensitivity and specificity for the detection of lung cancer. Thus, MAGE and SSX4 RT-PCR may be effectively utilized as additional methods to improve detection of lung cancer with using bronchial wash fluids.

Computer-aided nodule detection on digital chest radiography: validation test on consecutive T1 cases of resectable lung cancer

PURPOSE

To evaluate the usefulness of a commercially available computer-assisted diagnosis (CAD) system on operable T1 cases of lung cancer by use of digital chest radiography equipment.

MATERIALS AND METHODS

Fifty consecutive patients underwent surgery for primary lung cancer, and 50 normal cases were selected. All cancer cases were histopathologically confirmed T1 cases. All normal individuals were selected on the basis of chest computed tomography (CT) confirmation and were matched with cancer cases in terms of age and gender distributions. All chest radiographs were obtained with one computed radiography or two flat-panel detector systems. Eight radiologists (four chest radiologists and four residents) participated in observer tests and interpreted soft copy images by using an exclusive display system without and with CAD output. When radiologists diagnosed cases as positives, the locations of lesions were recorded on hard copies. The observers' performance was evaluated by receiver operating characteristic analysis.

RESULTS

The overall detectability of lung cancer cases with CAD system was 74% (37/50), and the false-positive rate was 2.28 (114/50) false positives per case for normal cases. The mean A(z) value increased significantly from 0.896 without CAD output to 0.923 with CAD output (P = 0.018). The main cause of the improvement in performance is attributable to changes from false negatives without CAD to true positives with CAD (19/31, 61%). Moreover, improvement in the location of the tumor was observed in 1.5 cases, on average, for radiology residents.

CONCLUSION

This CAD system for digital chest radiographs is useful in assisting radiologists in the detection of early resectable lung cancer.

Initial bronchoscopic treatment for patients with intraluminal bronchial carcinoids

OBJECTIVE

Carcinoid of the lung is considered low-grade malignancy, and less invasive treatment may therefore be considered. We analyzed the long-term outcome of initial bronchoscopic treatment in patients with intraluminal bronchial carcinoids.

METHODS

Initial bronchoscopic treatment was applied to improve presurgical condition, to obtain tissue samples for proper histologic classification, and to enable less extensive parenchymal resection. For intraluminal bronchial carcinoid, complete tumor eradication with initial bronchoscopic treatment was attempted. High-resolution computed tomography in addition to bronchoscopy was used to determine intraluminal versus extraluminal tumor growth. Surgery followed in cases of atypical carcinoid, residue, or recurrence.

RESULTS

Seventy-two patients, 43 of them female, have been treated (median age 47 years, range 16-80 years). Median follow-up has been 65 months (range 2-180 months). Fifty-seven (79%) had typical carcinoids and 15 (21%) had atypical carcinoids. Initial bronchoscopic treatment resulted in complete tumor eradication in 33 of 72 cases (46%), 30 typical and 3 atypical. Thirty-seven of 72 cases (51%), 11 atypical, required surgery (2 for late detected recurrences). Two patients had metastatic atypical carcinoid, 1 already at referral. Of the 6 deaths, 1 was tumor related.

CONCLUSIONS

Initial bronchoscopic treatment is a potentially more tissue-sparing alternative than immediate surgical resection in patients with intraluminal bronchial carcinoids. For successful tumor eradication with initial bronchoscopic treatment in central carcinoids, assessment of intraluminal versus extraluminal growth may be of much more importance than histologic division between typical and atypical carcinoid. Disease-specific mortality is low, and long-term outcome has been excellent. Implementation of initial bronchoscopic treatment had no negative impact on surgical treatment outcome.

Photodynamic therapy (PDT) in early central lung cancer: a treatment option for patients ineligible for surgical resection

OBJECTIVES

To review the Yorkshire Laser Centre experience with bronchoscopic photodynamic therapy (PDT) in early central lung cancer in subjects not eligible for surgery and to discuss diagnostic problems and the indications for PDT in such cases.

METHODS

Of 200 patients undergoing bronchoscopic PDT, 21 had early central lung cancer and were entered into a prospective study. Patients underwent standard investigations including white light bronchoscopy in all and autofluorescence bronchoscopy in 12 of the most recent cases. Indications for bronchoscopic PDT were recurrence/metachronous endobronchial lesions following previous treatment with curative intent in 10 patients (11 lesions), ineligibility for surgery because of poor cardiorespiratory function in 8 patients (9 lesions) and declined consent to operation in 3 patients. PDT consisted of intravenous administration of Photofrin 2 mg/kg followed by bronchoscopic illumination 24-48 h later.

RESULTS

29 treatments were performed in 21 patients (23 lesions). There was no procedure-related or 30 day mortality. One patient developed mild skin photosensitivity. All patients expressed satisfaction with the treatment and had a complete response of variable duration. Six patients died at 3-103 months (mean 39.3), three of which were not as a result of cancer. Fifteen patients were alive at 12-82 months.

CONCLUSION

Bronchoscopic PDT in early central lung cancer can achieve long disease-free survival and should be considered as a treatment option in those ineligible for resection. Autofluorescence bronchoscopy is a valuable complementary investigation for identification of synchronous lesions and accurate illumination in bronchoscopic PDT.

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.