Dynamic analysis of predictive biomarkers for radiation therapy efficacy in non-small cell lung cancer patients by next-generation sequencing based on blood specimens

Decoding the Dynamics of Circulating Tumor DNA in Liquid Biopsies

Circulating tumor DNA (ctDNA), a fragment of tumor DNA found in the bloodstream, has emerged as a revolutionary tool in cancer management. This review delves into the biology of ctDNA, examining release mechanisms, including necrosis, apoptosis, and active secretion, all of which offer information about the state and nature of the tumor. Comprehensive DNA profiling has been enabled by methods such as whole genome sequencing and methylation analysis. The low abundance of the ctDNA fraction makes alternative techniques, such as digital PCR and targeted next-generation exome sequencing, more valuable and accurate for mutation profiling and detection. There are numerous clinical applications for ctDNA analysis, including non-invasive liquid biopsies for minimal residual disease monitoring to detect cancer recurrence, personalized medicine by mutation profiling for targeted therapy identification, early cancer detection, and real-time evaluation of therapeutic response. Integrating ctDNA analysis into routine clinical practice creates promising avenues for successful and personalized cancer care, from diagnosis to treatment and follow-up.

The Predictive Value of 8-Hydroxy-Deoxyguanosine (8-OHdG) Serum Concentrations in Irradiated Non-Small Cell Lung Carcinoma (NSCLC) Patients

Ionizing radiation is strongly linked to direct or indirect DNA damage, as with the production of reactive oxygen species (ROS), which in turn produce DNA damage products, such as 8-hydroxy-2-deoxyguanosine (8-OHdG). In this study, we aimed to investigate the formation of 8-OHdG after irradiation in patients with non-small cell cancer (NSCLC) and its use as a biomarker. Sixteen patients with squamous and thirty-six patients with non-squamous pathology were included. An enzyme-linked-immunosorbent assay (ELISA) was performed before and after radiation. A dose-dependent relationship was confirmed: 8-OHdG plasma concentrations, increased in the total of NSCLC patients and specifically with a linear correlation in non-squamous pathology; in squamous histology, after an initial increase, a significant decrease followed after 20 Gy dose of irradiation. The pretreatment total irradiated tumor volume (cm3) was positively correlated with 8-OHdG levels in patients with squamous histology. When plotting the 8-OHdG plasma concentration at a 10 Gy irradiation dose to the baseline, the AUC was 0.873 (95% CI 0.614-0.984), p < 0.0001, with an associated criterion value of >1378 as a cutoff (sensitivity 72.7%, specificity 100%). When normalizing this ratio to BSA, the associated criterion cutoff value was >708 (sensitivity of 100%, specificity 80%). Lastly, 8-OHdG levels were closely related with the development of radiation-induced toxicities.