The purpose of this study is to observe the safety and effectiveness of the add-on of intraluminal brachytherapy with BRAXX esophageal brachytherapy applicator after definitive CCRT in patients with thoracic esophageal cancer.

Add-on of intraluminal brachytherapy with applicator:

Brachytherapy protocol starts within 12 weeks after EBRT (This is "week 1"). High-dose-rate (HDR) 5-Gy per fraction is delivered to GTV of esophageal tumor(s), second fraction (if applicable) to be done within 2 weeks after the first fraction, for a total of 5-10Gy in 1-2 fractions. GTV coverage D90 should equal 100% of prescription. It is NOT allowed to give concurrent chemotherapy on the days of HDR brachytherapy.

• Prior to undergoing any study-specific procedure, patients must read and sign the current Ethics Committee/Institutional Review Board (IRB)-approved informed consent form. All on-study procedures are permitted within the visit window of ± 2 week. CT with contrast (no contrast if contraindicated) will be done at months 6 and 9; CT or PET/CT will be done at week 12 and month 12; and endoscopy with or without biopsy will be done at week 12, month 6, 9 and 12 for evaluation of tumor response; OPD follows up at week12, month 6, 9 and 12. A patient will be withdrawn from this study in the situation of any grade 4 toxicities. As for any adverse effects≧grade3, dose reduction, or dose delay according to the tolerability of individual patients is allowed. Grade 3 toxicity will cause the rest of the treatment (at least 1 week) until recovery to ≤grade 2 toxicity. If any patient can not tolerate a full course of brachytherapy, the total dose (EBRT+brachytherapy) can be reduced to 60Gy without violation of protocol. The management of adverse effects will follow general principles. Because tumor response is usually observed after completion of treatment, patients will not withdraw from the study because of no response. However, patients should be withdrawn from the study of (1) any grade 4 toxicity or (2) any unexpected cause of SAE that needs to discontinue radiation such as stroke, heart attack, accident, infection, bleeding…etc. Any failure observed during the post-treatment period will be documented, and patients should be withdrawn from the study, facilitating other treatment interventions.
• During this 12-month trial, any other cancer treatment (such as target therapy) and any non-cancer treatment that can increase adverse reactions within the treatment field are prohibited, so as not to affect treatment outcome or cause a change in side effects. The general management of symptoms or other non-cancer-related treatment is allowed, as long as physicians confirm that the interpretation of treatment outcome or side effects will not be influenced.
• The Investigator may use the data collected in this study for future research; which shall be consented by the Subject in the consent form.

Inclusion Criteria:

• Age of 20-85 years, with ECOG performance 0-2.
• Thoracic esophageal cancer with clinical stage I-IV and biopsy proof; patient with stage I-IV cervical esophageal cancer could be recruited in this trial according to Investigator's assessment.
• Complete CCRT with total doses of 45-55Gy to GTV via external beam radiotherapy (EBRT).

Exclusion Criteria:

• According to Investigator's assessment, patients with double cancer or recurrence could be recruited in this trial if they continue to receive systemic therapy.
• Patient with double cancer, esophageal cancer or recurrence who is scheduled for surgery treatment.
• Involvement of tracheal mucosa or bronchial mucosa.
• Stenosis of esophageal lumen that cannot be bypassed by the applicator after EBRT.
• The distribution of the lesions of interest exceeds 10cm range.
• The patient is participating in other clinical trials.