Neoadjuvant chemoradiotherapy (CRT) followed by surgery or definitive CRT is the standard treatment for locally advanced esophageal squamous cell carcinoma (ESCC), but the clinical outcomes are not satisfactory. Breathomics testing is a promising, non-invasive, simple method for detection and screening for ESCC. This observational study aimed to role of exhaled volatile organic compounds (VOCs) in predicting the efficacy and risk of recurrence in patients with locally advanced ESCC who received CRT.

Neoadjuvant chemoradiotherapy (CRT) followed by surgery or definitive CRT is the standard treatment for locally advanced esophageal squamous cell carcinoma (ESCC), but the clinical outcomes are not satisfactory. Breathomics testing is a promising, non-invasive, simple method for detection and screening for ESCC. This observational study aimed to role of exhaled volatile organic compounds (VOCs) in predicting the efficacy and risk of recurrence in patients with locally advanced ESCC who received CRT. All patients will receive standard fractionation radiation therapy (RT) scheme: 40-50.4 Gy in 20-28 fractions over 4-6 weeks using intensity-modulated radiotherapy, concurrently with platinum- or taxane-based chemotherapy, with or without PD-1 inhibitors. All patients will undergo esophagectomy 6-8 weeks after the completion of neoadjuvant CRT. Dynamic breathing testing was performed before, during, and after radiotherapy.

Inclusion Criteria:

1. Histologically confirmed squamous cell carcinoma of the esophagus;
2. Absence of hematogenous metastasis disease, confirmed by endoscopic ultrasound (EUS) and PET-CT scan (according to UICC TNM version 8);
3. Age at diagnosis >18 years;
4. No prior cancer therapy;
5. Estimated life expectancy >6 months;
6. Eastern Cooperative Oncology Group performance status ≤ 2
7. No history of concomitant or previous malignancy;
8. The function of important organs meets the following requirements: a. white blood cell count (WBC) ≥ 4.0×109/L, absolute neutrophil count (ANC) ≥ 1.5×109/L; b. platelets ≥ 100×109/L; c. hemoglobin ≥ 9g/dL; d. serum albumin ≥ 2.8g/dL; e. total bilirubin ≤ 1.5×ULN, ALT, AST and/or AKP ≤ 2.5×ULN; f. serum creatinine ≤ 1.5×ULN or creatinine clearance rate >60 mL/min;
9. Ability to understand the study and sign informed consent.

Exclusion Criteria:

1. Patients who have been treated previously with anti-tumor therapy (including chemotherapy, radiotherapy, surgery, immunotherapy, etc.);
2. Patients with hematogenous metastasis disease at diagnosis;
3. Female patients who are pregnant or lactating;
4. Inability to provide informed consent due to psychological, familial, social and other factors;
5. Patients who cannot tolerate chemoradiotherapy due to severe cardiac, lung, liver or kidney dysfunction, or hematopoietic disease or cachexia.
6. The physical condition is not enough to provide 0.5L exhalation at one time.

A total of 230 patients with ESCC who undergo neoadjuvant chemoradiotherapy or definitive radiotherapy will be included.