Screening for lung cancer

Methylation of DROSHA and DICER as a Biomarker for the Detection of Lung Cancer

Simple Summary

To identify possible biomarkers for early detection of lung cancer we assessed the methylation status of genes related to carcinogenesis, DICER and DROSHA, in lung cancer patients and healthy volunteers. The relative level of methylation of DROSHA was significantly lower and DICER significantly higher in cancer patients. The relative level of methylation of DROSHA was significantly higher in patients with early-stage NSCLC (IA-IIIA) and could discriminate them from healthy people with a sensitivity of 71% and specificity of 76% for the first region and with a sensitivity of 60% and specificity of 85% for the second region. Analysis of the first region of the DICER enabled the distinction of NSCLC patients from healthy individuals with a sensitivity of 96% and specificity of 60%. The results indicate that the assessment of DICER and DROSHA methylation status can potentially be used as a biomarker for the early detection of lung cancer.

Abstract

Background: Lung cancer is the leading cause of cancer-related deaths. Early diagnosis may improve the prognosis. Methods: Using quantitative methylation-specific real-time PCR (qMSP-PCR), we assessed the methylation status of two genes (in two subsequent regions according to locations in their promoter sequences) related to carcinogenesis, DICER and DROSHA, in 101 plasma samples (obtained prior to the treatment) of lung cancer patients and 45 healthy volunteers. Results: The relative level of methylation of DROSHA was significantly lower (p = 0.012 for first and p < 0.00001 for the second region) and DICER significantly higher (p = 0.029 for the first region) in cancer patients. The relative level of methylation of DROSHA was significantly (p = 0.037) higher in patients with early-stage NSCLC (IA-IIIA) and could discriminate them from healthy people with a sensitivity of 71% and specificity of 76% (AUC = 0.696, 95% CI: 0.545–0.847, p = 0.011) for the first region and with a sensitivity of 60% and specificity of 85% (AUC = 0.795, 95% CI: 0.689–0.901, p < 0.0001) for the second region. Methylation analysis of the first region of the DICER enabled the distinction of NSCLC patients from healthy individuals with a sensitivity of 96% and specificity of 60% (AUC = 0.651, 95% CI: 0.517–0.785, p = 0.027). The limitations of the study include its small sample size, preliminary nature, being an observational type of study, and the lack of functional experiments allowing for the explanation of the biologic backgrounds of the observed associations. Conclusion: The obtained results indicate that the assessment of DICER and DROSHA methylation status can potentially be used as a biomarker for the early detection of lung cancer.

Delays in Managing Lung Cancer: The Importance of Fast-Tracking in the Clinical Care

Early diagnosis in lung cancer is desirable, because surgical resection offers the only hope of cure. In the face of suggestive symptoms, a normal plain chest radiograph does not exclude the diagnosis, and investigation is essential. The various imaging changes seen on computerized tomography and PET scan provide strong suggestive evidence of lung cancer, but proof of diagnosis rests on histologic examination, material that may be obtained by one of the following diagnostic procedures: bronchoscopy, mediastinoscopy, fine needle aspiration biopsy, thoracentesis and pleural biopsy, lymph node biopsy, and exploratory thoracotomy.

High Aldehyde Dehydrogenase Levels Are Detectable in the Serum of Patients with Lung Cancer and May Be Exploited as Screening Biomarkers

Objectives

Since early detection improves overall survival in lung cancer, identification of screening biomarkers for patients at risk represents an area of intense investigation. Tumor liberated protein (TLP) has been previously described as a tumor-associated antigen (complex) present in the sera from lung cancer patients. Here, we set out to identify the nature of TLP to develop this as a potential biomarker for lung cancer screening.

Materials and Methods

Beginning from the peptide epitope RTNKEASI previously identified from the TLP complex, we produced a rabbit anti-RTNKEASI serum and evaluated it in the lung cancer cell line A549 by means of immunoblot and peptide completion assay (PCA). The TLP sequence identification was conducted by mass spectrometry. The detected protein was, then, analyzed in patients with non-small cell lung cancer (NSCLC) and benign lung pathologies and healthy donors, by ELISA.

Results

The anti-RTNKEASI antiserum detected and immunoprecipitated a 55 kDa protein band in the lysate of A549 cells identified as aldehyde dehydrogenase isoform 1A1, revealing the molecular nature of at least one component of the previously described TLP complex. Next, we screened blood samples from a non-tumor cohort of 26 patients and 45 NSCLC patients with different disease stages for the presence of ALDH1A1 and global ALDH. This analysis indicated that serum positivity was highly restricted to patients with NSCLC (ALDH p < 0.001; ALDH1A1 p=0.028). Interestingly, the global ALDH test resulted positive in more NSCLC samples compared to the ALDH1A1 test, suggesting that other ALDH isoforms might add to the sensitivity of the assay.

Conclusion

Our data indicate that ALDH levels are elevated in the sera of NSCLC patients, even with early stage disease, and may thus be evaluated as part of a marker panel for non-invasive detection of NSCLC.

Update on biomarkers for the detection of lung cancer

Patients at risk for lung cancer may have subclinical disease for years before presentation. The diagnosis of this disease is primarily based on symptoms, and detection often occurs after curative intervention is no longer possible. At present, no lung cancer early-detection biomarker is clinically available. This study reviews the most recent advances in early detection and molecular diagnostic biomarkers for the detection of lung cancer. This review includes an overview of the various biological specimens and matrices in which these biomarkers could be analyzed, as well as the diverse strategies and approaches for identifying new biomarkers that are currently being explored. Several novel and attractive biomarker candidates for the early detection of lung cancer exist. A remarkable shift is taking place from research based on single markers to analyzing signatures that are more complex in order to take advantage of new high-throughput technologies. However, it is still necessary to validate the most promising markers and the standardization of procedures that will lead to specific clinical applications.

Nael Martini: a leader in thoracic surgical oncology

Nael Martini was one of the leading academic general thoracic surgeons of the late 20th century. His most notable contributions related to the surgical and multimodality treatment of lung cancer.

Positron-emission tomography as a prognostic tool for early-stage lung cancer

BACKGROUND

Positron-emission tomography (PET) shows tissue metabolic activity in the form of the standard uptake value (SUV). This study examines the prognostic value of the SUV for early-stage lung cancer.

METHODS

A retrospective review of 187 patients undergoing PET for potential lung cancer. Data collected included patient demographics, tumor pathology, and survival information. Data were correlated with PET results to determine if a prognostic relationship exists.

RESULTS

The sensitivity and specificity of PET for detecting malignant lesions were 98% and 24%. Malignant lesions had a higher SUV than benign lesions (5.9 +/- 6.2 versus 2.2 +/- 1.8, P < .0001). The average SUV of well-differentiated tumors was 2.6 +/- 3.1 versus 5.9 +/- 5.5 for other tumors (P = .010). There was a strong correlation between tumor stage and SUV (analysis of variance, P < .0001). There was no difference in tumor SUV for survivors versus nonsurvivors.

CONCLUSIONS

The SUV correlates with prognostic indicators, such as tumor stage and grade. The SUV alone was not an independent predictor of survival.

Lung Cancer After Heart Transplantation: A 17-Year Experience

BACKGROUND

The effects of heart transplantation on lung cancer incidence in heart transplant recipients are unclear.

METHODS

In an observational study, we retrospectively reviewed the charts of all patients undergoing heart transplantation at our institution from July 1982 to July 1999. Data on lung cancer incidence, risk factors, treatment, and outcome were collected.

RESULTS

Five hundred seventy-two patients (mean age, 50 +/- 11 years; range, 18 to 73) were considered at risk for lung cancer. Of these, 324 (57%) had a more than 20 pack-year history of smoking before transplantation. Lung cancer developed in 2 patients 1 year or less after transplantation and in 8 patients more than 1 year after transplantation (incidence, 2.2 per 1,000 patients per year of follow-up). Non-small cell lung cancer was diagnosed in all cases. Median survival was 10.8 months (range, 2 to 37.5). Routine annual chest radiographs after transplantation enabled early diagnosis in 5 cases (stages Ia and IIa), which correlated with better mean survival (28.1 months [range, 19 to 37.5] versus 5.1 months [range, 2 to 10.8]; p = 0.0002).

CONCLUSIONS

The incidence of lung cancer in our population of heart transplant recipients appears to be no higher than in nontransplant populations with similar risk factors (ie, smoking and age). Routine radiographic imaging of transplant recipients may allow earlier detection of lung cancer and thus offer a survival benefit.

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

BACKGROUND

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

SYNTHESIS

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

RESULTS

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

ANALYSIS

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

CONCLUSIONS

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

Women and lung cancer: waiting to exhale

Lung cancer is now the leading cause of cancer deaths among women. In the United States, 64,300 women are expected to die of lung cancer in 1996. Smoking is responsible for about 80% of lung cancer cases. Unfortunately, the prevalence of smoking among women remains unacceptably high at about 22% and is expected to surpass the rate in men by the year 2000. Smoking rates are highest among young girls and the less educated. Whether lung cancer represents a different disease in women than in men is unclear. Data are conflicting regarding the magnitude of the relative risk of developing lung cancer due to smoking between the genders. There appears to be a difference in the relative distribution of lung cancer histologic features between men and women that is not explained entirely by differences in smoking patterns. Women who smoke appear to be at higher risk of developing small cell lung cancer than squamous cell lung cancer, whereas men who smoke have a similar risk for the two histologic conditions. Furthermore, women smokers are more likely to develop adenocarcinoma of the lung, and estrogens may play a causative role in this phenomenon. Data are unclear regarding whether the outcome of lung cancer treatment differs between genders. Solutions to the lung cancer epidemic among US women include (1) prevention of the disease by reducing smoking rates, (2) improving early detection methods, and (3) exploring new therapeutic strategies.

Delays in the diagnosis and surgical treatment of lung cancer

BACKGROUND

Patients admitted for resection of lung tumours frequently experience lengthy delays in diagnosis and preoperative investigations. This study was conducted to quantify this delay between presentation and definitive treatment and to assess the factors responsible for such a delay.

METHODS

All patients undergoing lung resection for a tumour at a single surgical unit in 1993 were studied. The date of each consultation, investigation, and referral was identified, and the extent of any delay determined.

RESULTS

The mean total delay from presentation to operation was 109 days. Within this period an average of one month occurred before referral to a respiratory specialist who then spent two months investigating the patient. After referral to a surgeon, surgery took place within a mean interval of 24 days.

CONCLUSIONS

These delays to definitive treatment appear unacceptable. Points at which the efficiency of the diagnostic process could be improved are discussed. The length of delay did not correlate with tumour stage in this study.

Future directions in clinical research for lung cancer

Even since the Surgeon General's 1964 report, the mortality rate from lung cancer has continued to rise. Although there is evidence that this continued increase in mortality will slow or level in the next decade, lung cancer mortality is a major health problem destined to remain with us for at least the next generation. There have been no established advances in the early detection or prevention of lung cancer in the last 30 years and our therapies have increased the cure rate only from 5 to 13% in this 30-year interval. Biologic advances have outpaced clinical advances in recent times and many of the advances are now ripe for clinical exploitation. There are currently more exciting clinical trials for all phases of lung cancer than at any time and it will be stimulating to witness the results of the clinical trials discussed herein. Hopefully, the results of these studies will lead to a decrease in lung cancer mortality in the next century, much as it increased in the past century.

DNA flow cytometric studies of 66 human lung tumors analyzed before treatment. Prognostic implications

To investigate the prognostic implications of DNA flow cytometry in human lung tumors, we analyzed specimens from patients with neoplastic and non-neoplastic lung disease. Most non-neoplastic and normal (taken at the resection border) lung samples yielded a single cell population with diploid DNA content (only two normal lung specimens from two cancer patients had aneuploid DNA content). At least one aneuploid cell subpopulation was seen in 91 percent of NSCLC and 50 percent on SCLC. To show intratumor heterogeneity, multiple-site sampling was done whenever possible in both primary tumor and metastatic sites, revealing a high incidence of multiclonality (50 percent). Although diploid tumors were rare, they associated with a higher survival rate than aneuploid monoclonal and multiclonal tumors with hypoploid and/or hypertetraploid clones, which had the lowest survival. Cellular DNA content analysis in patients with lung tumors may be useful in prognostic evaluation.