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P1.06 - Poster Session 1 - Prognostic and Predictive Biomarkers (ID 161)
- Event: WCLC 2013
- Type: Poster Session
- Track: Biology
- Presentations: 1
- Coordinates: 10/28/2013, 09:30 - 16:30, Exhibit Hall, Ground Level
P1.06-021 - Validation of DNA Hypermethylation Analysis in Sputum for the Diagnosis of Lung Cancer (ID 1774)
09:30 - 16:30 | Author(s): H.J. Smit
Lung cancer has the highest mortality of all cancers worldwide with a 5 year survival rate of <15%. The prognosis improves dramatically when the disease is detected at an early stage, and when curative treatment is possible. Current (low dose CT) screening and diagnostic procedures are suboptimal with low specificity. Thus, novel detection methods for lung cancer as stand alone or in combination with other methods are needed. DNA hypermethylation of biomarkers in sputum have shown to distinguish lung cancer cases from cancer-free controls. The aim of the present study was to validate the usage of DNA hypermethylation of biomarkers in sputum samples of lung cancer patients and controls for lung cancer diagnosis, in comparison with sputum cytology.
We prospectively collected sputum of lung cancer patients and controls during 3-9 days in the Amsterdam and Nieuwegein area, The Netherlands. From this sputum bank, a learning set (n=80 lung cancer patients, n=91 controls) and validation set (n=173 lung cancer patients, n=164 controls) were randomly composed. DNA promoter hypermethylation of the following biomarkers was assessed by means of quantitative methylation specific PCR: RASSF1A, APC, cytoglobin, 3OST2, PRDM14, FAM19A4 and PHACTR3. Cut-off values for positive hypermethylation were calculated using Youden’s index. Sputum cytology analysis was performed for all sputum samples. McNemar’s test was used to compare the difference between sensitivity of hypermethylation and sputum cytology for lung cancer diagnosis. A two-sided p-value <0.05 was considered significant.
RASSF1A was best able to distinguish cases from controls, with sensitivity of 37-41% and specificity of 91-97% in both learning and validation sets. In multivariate analysis, a panel of RASSF1A, 3OST2 and PRDM14 showed highest sensitivity of 82% [95% confidence interval (CI): 76 – 88%] with a specificity of 68% [95% CI: 61 – 74%] in the learning set, with consistent results in the validation set. Molecular analysis was superior (P<0.001) over sputum cytology (sensitivity of 15%). The sensitivity of the biomarker panel did not improve when it was combined with sputum cytology. There was no association observed between DNA hypermethylation and clinical parameters such as age, smoking status, tumor stage, and histology.
This study validates hypermethylation analysis in sputum for the diagnosis of lung cancer. RASSF1A hypermethylation showed high specificity and thereby can have an important role in lung cancer diagnosis in symptomatic patients. A panel of biomarkers RASSF1A, 3OST2 and PRDM14 showed high sensitivity, but relatively low specificity.