Circulating Cell Free DNA as Predictive Biomarker in Cervical Cancer Patients Treated with Radical Chemo-Radiation

Abstract

<h3>Purpose/Objective(s)</h3> Liquid biopsy is a new technique for cancer detection. Evaluation of circulating cell-free DNA (ccfDNA) through liquid biopsy is a minimally invasive and cost-effective method that may serve as a potential biomarker for early detection, treatment monitoring, status of residual disease, and distant tumor metastasis in cervical cancer patients. We evaluated plasma ccfDNA levels in patients of cervical cancer undergoing chemo-radiation and correlated their levels with treatment response and short-term clinical outcome. <h3>Materials/Methods</h3> This prospective, single arm, open–label, observational pilot study included patients of cervical cancer, being radically treated with three-dimensional conformal radiotherapy or intensity modulated radiotherapy to a dose of 46Gy/23 fractions over 4.5weeks followed by high dose rate (HDR) brachytherapy to deliver EQD2 of >80Gy. Concurrent weekly cisplatin 40mg/m² was administered weekly throughout the course of external radiotherapy. Peripheral blood samples were collected in EDTA tubes before starting treatment and at 6months after completion of treatment. On the same day, tubes were centrifuged at 800g for 10 minutes. The supernatant was transferred to 10ml tubes and centrifuged at 1600g for 10 minutes to remove debris. Plasma supernatants were transferred in 1mL aliquots and stored at -80°C. Total genomic DNA of plasma aliquots were extracted using the commercially available Circulating Nucleic Acid Kits. Categorical variables were tested using the chi-square test. Univariate analysis was done to analyze the factors affecting ccfDNA levels and if found significant, multivariate analysis was used. <h3>Results</h3> Of 22 patients of histologically confirmed cervical cancer, 11 (50%) were of stage II disease followed by 7 (31.8%) with stage III disease. The median age was 53.5 years (range 39-70 years). The baseline mean ccfDNA levels was 69.68±58.335 ng/μL which was significantly reduced post-treatment to 0.452±0.199 ng/μL (p<0.001). The stage of the disease significantly affected the baseline ccfDNA levels (p=0.029). Positive pelvic and para-aortic lymph nodes showed a trend towards higher baseline ccfDNA levels (p=0.068 and 0.38 respectively). Patients with progressive disease had a trend towards higher post-treatment ccfDNA levels (p=0.19). <h3>Conclusion</h3> Our study revealed the role of ccfDNA as a potential biomarker in cervical cancer, which, however requires further longitudinal studies for confirmation.