Inclusion Criteria: 

PRIOR TO STEP 1 REGISTRATION

• Histologically proven diagnosis of adenocarcinoma or squamous cell carcinoma of the thoracic esophagus or gastroesophageal junction (Siewert I-II).
• Stage I-IVA, excluding T4b, according to the American Joint Committee on Cancer (AJCC) 8th edition based on the following diagnostic workup:
  • History/physical examination;
  • Whole-body fludeoxyglucose F-18 (FDG)-positron emission tomography (PET)/computed tomography (CT) with or without (+/-) contrast (preferred) or chest/abdominal (include pelvic if clinically indicated) CT with contrast.
• For patients who DID NOT receive induction chemotherapy, scan must occur within 30 days prior to Step 1 registration.
• For patients who DID receive induction chemotherapy, scan must occur: 
  • Within 30 days after final induction chemotherapy dose; OR
  • Within 30 days prior to Step 1 registration.
    • Note: Patients who had prior endoscopic mucosal resection (EMR) with a diagnosis of AJCC stage I-IVA, excluding T4b, esophageal cancer are eligible.
• Surgical consultation to determine whether or not the patient is a candidate for resection after completion of chemoradiation.
• Induction chemotherapy for the current malignancy prior to concurrent chemoradiation allowed if last dose is no more than 90 days and no less than 10 days prior to Step 1 registration.
• Zubrod performance status 0, 1, or 2.
• Absolute neutrophil count (ANC) (within 30 days prior to Step 1 registration):
  • For patients who DID NOT receive induction chemotherapy: ANC ≥ 1,500 cells/mm^3;
  • For patients who DID receive induction chemotherapy: ANC ≥ 1,000 cells/mm^3.
• Platelets (within 30 days prior to Step 1 registration):
  • For patients who DID NOT receive induction chemotherapy: Platelets ≥ 100,000/uL;
  • For patients who DID receive induction chemotherapy: Platelets ≥ 75,000/uL.
• Hemoglobin ≥ 8.0 g/dl.
  • Note: The use of transfusion or other intervention to achieve Hgb ≥ 8.0 g/dl is acceptable (within 30 days prior to Step 1 registration).
• Creatinine clearance > 50 mL/min estimated by Cockcroft-Gault formula (within 30 days prior to Step 1 registration).
• Total bilirubin ≤ 1.5 x upper limit of normal (ULN) (within 30 days prior to Step 1 registration).
• Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) ≤ 3 x ULN (within 30 days prior to Step 1 registration). 
• Negative pregnancy test (serum or urine) within 14 days prior to Step 1 registration for women of child bearing potential.
• The patient or a legally authorized representative must provide study-specific informed consent prior to study entry.

Exclusion Criteria: 

• Cervical esophageal cancers arisen from 15-18 cm from the incisors. 
• Patients with T4b disease according to the AJCC 8th edition.
• Definitive clinical or radiologic evidence of metastatic disease.
• Any active malignancy within 2 years of study registration that may alter the course of esophageal cancer treatment. 
• Prior thoracic radiotherapy that would result in overlap of radiation therapy fields.
• Severe, active co-morbidity defined as follows: 
  • Active uncontrolled infection requiring IV antibiotics at the time of Step 1 registration;
  • Symptomatic congestive heart failure, unstable angina, or cardiac arrhythmia not controlled by pacer device at the time of Step 1 registration; 
  • Myocardial infarction within 3 months prior to Step 1 registration.
• Pregnant and/or nursing females. 
• Human immunodeficiency virus (HIV) positive with CD4 count < 200 cells/microliter. Note that patients who are HIV positive are eligible, provided they are under treatment with highly active antiretroviral therapy (HAART) and have a CD4 count ≥ 200 cells/microliter within 30 days prior to registration.
  • Note also that HIV testing is not required for eligibility for this protocol. This exclusion criterion is necessary because the treatments involved in this protocol may be significantly immunosuppressive.

PRIOR TO STEP 2 REGISTRATION

• Unable to obtain confirmation of payment coverage (insurance or other) for either possible radiation treatment.