The Absence of Mutations in the Exon 2 KRAS Gene in Several Ethnic Groups in North Sumatra May Not the Main Factor for Lung Cancer

The role of oncogenes and tumor suppressor genes in determining survival rates of lung cancer patients in the population of North Sumatra, Indonesia

Background: Gaining a better understanding of molecular alterations in the pathogenesis of lung cancer reveals a significant change in approach to the management and prognosis of lung cancer. Several oncogenes and tumor suppressor genes have been identified and have different roles related to survival rates in lung cancer patients. This study aims to determine the role of KRAS, EGFR, and TP53 mutations in the survival rate of lung cancer patients in the population of North Sumatra. Methods: This is a retrospective cohort study involving 108 subjects diagnosed with lung cancer from histopathology specimens. DNA extractions were performed using FFPE followed by PCR examinations for assessing the expressions of EGFR, RAS, and TP53 protein. Sequencing analysis was carried out to determine the mutations of EGFR exon 19 and 21, RAS protein exon 2, and TP53 exon 5-6 and 8-9. Data input and analysis were conducted using statistical analysis software for Windows. The survival rate analysis was presented with Kaplan Meier. Results: 52 subjects completed all procedures in this study. Most of the subjects are male (75%), above 60 years old (53.8%), heavy smokers (75%), and suffer from adenocarcinoma type of lung cancer (69.2%). No subjects showed KRAS exon 2 mutations. Overall survival rates increased in patients with EGFR mutations (15 months compared to 8 months; p=0.001) and decreased in patients with TP53 mutations (7 months compared to 9 months; p=0.148). Also, there was increasing Progression-Free Survival in patients with EGFR mutations (6 months compared to 3 months) ( p=0.19) and decreasing PFS in patients with TP53 mutations (3 months compared to 6 months) ( p=0.07). Conclusions: There were no KRAS mutations in this study. EGFR mutations showed a higher survival rate, while TP53 mutations showed a lower survival rate in overall survival and progression-free survival.

Concordance of Epidermal Growth Factor Receptor Mutation from Tissue Biopsy and Plasma Circulating Tumor DNA in Treatment-Naïve Lung Adenocarcinoma Patients

Background: Prevalence of Epidermal Growth Factor Receptor (EGFR) mutation in ctDNA in treatment-naïve individuals are not well established in Indonesia. In recent years, ctDNA as a specific and sensitive blood-based biomarker had been developed to detect the mutation. The study was done to understand the concordance and acceptance levels of ctDNA in detecting the gene mutation in lung adenocarcinoma patients.    Methods: This study used cross-sectional approach with purposive sampling design in 100 treatment-naïve NSCLC, adenocarcinoma patients. Samples were obtained from bronchoscopy, and blood, which were examined to detect the mutation in formalin-fixed, paraffin-embedded (FFPE) specimens or plasma samples using QIAampDNA Micro Kit. Mutation was calculated by droplet digital PCR (ddPCR).   Results: A hundred subjects with primary tumor tissue samples were compared with the plasma samples and mutation was detected in 20 patients (20.0%), 12 (12.0%) on exon 19, 7 (7.0%) on exon 21 and 1 (1.0%) on both exon 19 and 21. Within the plasma samples, mutation was found in 15 patients (15%) with mutation on exon 19 and 21 in 12 (12.0%) and 3 (3.0%) patients, respectively.  Within the two samples, concordance of EGFR mutation was 83.0% (83/100, P<0.001; correlation index: 0.42). Assuming presence of mutation as the benchmark, the accuracy of mutation presence in plasma DNA was 60.0% (9/15). Kappa test showed a weak agreement between the mutation in tissues and plasma, with a coefficient of 0.414 (95% CI).   Conclusion: Tissue biopsy was still considered as the main option to detect EGFR mutation in lung cancer. More research on ctDNA as the standardized tools to detect the mutation are required.