The Application Value Of Plasma Cell-free DNA In Cervical Cancer

Objective: Cervical cancer is a common malignant tumor of the female reproductive system.The prevention strategy at present is early screening and vaccination.However,due to the large population and uneven regional development,screening and vaccination have not been fully universalized in China.The morbidity rate of cervical cancer is still high.At present,chemotherapy is widely used in a comprehensive treatment for cervical cancer combined with surgery and radiotherapy.The response evaluation of cervical cancer treatment is mainly based on tumor markers and imaging methods such as ultrasound and Magnetic Resonance Imaging(MRI).But the sensitivity and specificity of tumor markers are limited,and imaging methods are difficult to track changes in the tumor burden of patients after cancer resection.Therefore,there are no suitable markers that can reflect the treatment effect of cervical cancer immediately.This study explored the genomic variation of plasma cell-free DNA in cervical cancer during treatment,and it is hoped that suitable markers can be found from plasma cell-free DNA to assess the effect of treatment.Methods: The peripheral blood and cervical tissue were collected during the treatment of cervical cancer patients.The relationships between the level of plasma cell-free DNA and the clinical characteristics of cervical cancer patients were analyzed.The whole exome sequencing was performed on plasma cell-free DNA,leukocyte DNA,cancer tissue,and adjacent tissue respectively.The biological characteristics of cell-free DNA were analyzed during the treatment of patients with cervical cancer.The clonal development process was performed according to the mutation frequency of plasma cell-free DNA in different timepoint of the patients.Functional analysis was performed on the mutation sites,and the genomic variation of cervical cancer was further analyzed.Results: The level of plasma cell-free DNA was positively correlated with cervical cancer stages,and positively correlated with patients' age.The level of plasma cell-free DNA decreased after neoadjuvant chemotherapy,and increased after the operation.In terms of biological characteristics,the frequency of cell-free DNA short fragment decreased after neoadjuvant chemotherapy and increased after surgery;the frequency of long fragment did not change significantly after neoadjuvant chemotherapy,but decreased after surgery.81 motifs changed significantly after surgery,including 52 motifs increased,and 29 motifs decreased.In addition,this research has also developed an algorithm to successfully detect reliable mutation sites from low-depth sequencing data in cell-free DNA,and functional analysis was performed on the identified mutant genes.It is found that there are 12 mutant genes related to HPV integration in plasma cell-free DNA.The mutated gene TUBGCP6 in plasma cell-free DNA is low expressed in cervical cancer tissues,and the prognosis of cervical cancer patients with TUBGCP6 low expression is poor.Conclusion: The levels and biological characteristics of plasma cell-free DNA change dynamically during the treatment of cervical cancer.Genomic variation of cervical cancer during the treatment can be studied through whole exome sequencing of plasma cell-free DNA,so as to monitor the treatment response of cervical cancer and guide clinical individualized treatment.