Application of ctDNA in Evaluation of Neoadjuvant Chemotherapy Efficacy and Exploration of Chemoresistance Mechanisms in Pancreatic Cancer

Inclusion Criteria:

* Newly diagnosed patients with non-metastatic pancreatic cancer;
* The pathological features were identified as pancreatic ductal carcinoma;
* Patients with clinical risk factors including significantly elevated CA19-9 levels at diagnosis, large primary tumor volume, large regional lymph node diameter, significant weight loss, and extreme pain;
* Patients accept neoadjuvant chemotherapy voluntarily with the regimen of modified FOLFIRINOX, and disease evaluation should be conducted every two courses, surgery should be performed without delay if resection criteria have been met, and at least two courses of chemotherapy should be completed;
* Age ≥18 years old;
* No other tumor treatment within 4 weeks prior to enrollment;
* Complete clinical data, including basic information, pathological information, treatment information;
* The subjects voluntarily join the study and sign the informed consent with good compliance, and cooperate with the acquisition of tissue samples and regular blood samples.

Exclusion Criteria:

* Any other systemic antitumor therapy priorly;
* Concomitant malignancies under treatment;
* Patients with a history of allergy to relevant chemotherapy agents;
* Failure to comply with the requirements of the visit plan;
* Patients who may be absent from the visit period for 2 weeks or more during the treatment period;
* The researchers determine that the subjects have other factors that could have caused the study to be discontinued.