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N. Kawakita
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P1.06 - Poster Session/ Screening and Early Detection (ID 218)
- Event: WCLC 2015
- Type: Poster
- Track: Screening and Early Detection
- Presentations: 1
- Moderators:
- Coordinates: 9/07/2015, 09:30 - 17:00, Exhibit Hall (Hall B+C)
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P1.06-005 - The Correlation between Visceral Pleural Invasion in T1a Non-Small Lung Cancer and Lymph Node Metastasis (ID 2638)
09:30 - 09:30 | Author(s): N. Kawakita
- Abstract
Background:
Visceral pleural invasion (VPI) of non-small cell lung cancer (NSCLC) has been recognized as a poor prognostic factor. Peripheral lung cancers often invade visceral pleura, and positive VPI upstages the T category of tumors from T1a to T2a. In addition, it is possible that peripheral lung cancers with positive VPI causes lymph nodes metastasis because of subpleural lymphovascular invasion. In this study, we statistically analyzed the correlation between VPI and lymph node metastasis.
Methods:
129 patients with NSCLC and a tumor diameter of ≤ 2cm underwent lobectomy or segmentectomy with systematic lymph node dissection in Tokushima University Hospital between January 2008 to December 2013. Excluding 11 patients who were not examined by FDG-PET before the surgery, we reviewed the medical records of 118 patients to obtain information on age, sex, CEA, SUVmax, CT findings, pathological VPI and lymph node metastasis.
Results:
Patient characteristics were as follows: median age of 66.5 (range: 41-86); male/female: 52/66; histologic type adenocarcinoma/squamous cell carcinoma/other: 103/12/3. 13(36.1%) of 36 patients who were suspected to be with visceral pleural invasion by preoperative CT findings were diagnosed with pathological visceral pleural invasion. The mean SUVmax on FDG-PET in patients with VPI was significantly higher than that of patients without VPI(p=0.01). Pathological visceral pleural invasion was identified in 19(16.1%) of 118 patients and associated with high incidence of lymph node metastasis significantly on multivariable analyses (p=0.00).
Conclusion:
VPI is important factors of lymph node involvement in small peripheral lung cancers. It is difficult to identify VPI of peripheral lung cancers by preoperative CT findings. FDG-PET may be useful for diagnose VPI.
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P2.08 - Poster Session/ Thymoma, Mesothelioma and Other Thoracic Malignancies (ID 225)
- Event: WCLC 2015
- Type: Poster
- Track: Thymoma, Mesothelioma and Other Thoracic Malignancies
- Presentations: 1
- Moderators:
- Coordinates: 9/08/2015, 09:30 - 17:00, Exhibit Hall (Hall B+C)
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P2.08-033 - DNA Methylation on Promotor Region of RASSF1 Gene in Thymic Neuroendocrine Tumor Is Higher than B3 Thymoma and Thymic Squamous Cell Carcinoma (ID 2544)
09:30 - 09:30 | Author(s): N. Kawakita
- Abstract
Background:
RASSF1 gene, located in 3p21.3, has eight exons and two promotor regions. RASSF1 is very famous tumor suppressor gene in various cancers. It was reported that DNA methylation on promotor region of RASSF1 in lung cancer, bladder cancer, and breast cancer and so on was higher, additionally low expression of RASSF1 was possible to cause to be poor prognosis. It is few reports about epigenome status in thymic epitherial tumors. We planned to explore DNA methylation in thymic epitherial tumors cyclopedically.
Methods:
①DNA and RNA were extracted from frozen specimen of B3 thymomas (8cases), thymic cancers (8cases), and thymic neuroendocrine tumors(NET)(3cases). ②DNA was treated by bisulfite conversion. ③DNA methylation level in 470000 CpG sites were measured by infinium methylation assay (Human methylation 450K; ILLMINA) exhaustively. ④DNA methylation on promotor regions of RASSF1 was measured by pyrosequencing（PyroMARK[TM]system;QIAGEN）. ⑤Expression level of mRNA was measured by Real time RT-PCR(Thermal Cycler Dice® Real Time System Single; Takara), using TaqMan Gene Expression Assays (Hs00200394_m1；Applied Biosystems). Internal reference gene is GAPDH（Hs02758991_g1；Applied Biosystems). ⑥Expression level of protein was analysed by immunostaining. Anti-RASSF1a antibody（Anti-RASSF1a antibody [3F3] ab23950, Mouse monoclonal, abcam）was used by CSAⅡmethod（DAKO CSA II, Biotin-Free Catalyzed Amplification System）.
Results:
Significant difference of DNA methylation was recognized by analysis of infinium methylation assay. All 11 CpG sites were configured on 1α promotor region of RASSF1 in this assay. This assay showed DNA methylation level was highest in NET group. DNA methylation level were 70.9±4.9% in NET, 22.2±20.0% in thymic cancer, 14.3±12.3% in B3 thymoma. ( NET vs Cancer/B3 t-test：P<0.00001). Pyrosequencing showed DNA methylation level were 24.0±13.1% in NET, 3.0±0.5% in thymic cancer, 3.0±0.9% in B3 thymoma. Real time RT-PCR showed that relative expression level (/normal thymus) were 0.48±0.31 in NET, 1.02±0.82 in carcinoma, 2.13±2.93 in B3 thymoma ( NET vs Carcinoma/B3 t-test：P=0.16). Immunostaining of RASSF1 was scored by stain intensity and stain extend. Immunostaining scoring of RASSF1 showed expression inhibition rate were 66% in NET, 50% in thymic cancer, 14% in B3 thymoma.
Conclusion:
The infinium methylation assay showed that DNA methylation on promotor region of RASSF1 in NET is higher than B3 thymoma and thymic cancer. The pyrosequencing validated this result. It was tendency to suppress the mRNA or protein expression of RASSF1 in NET, compared to other tumors. It is possible that aberrant DNA methylation on promotor region of RASSF1 may be specific change in NET among thymic epitherial tumors. Now we collected 8 formalin-fixed paraffin-embedded samples of thymic NETs to perform pyrosequencing and immunostaining of RASSF1 gene.
